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Kumar Saurav

University of Haifa, Marine Biology, Post-Doc

VIT University, School of Bioscience and Technology, Graduate Student

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Address: Dr. Kumar Saurav
Post Doctoral Fellow
Department of Marine Biology
Leon H. Charney School of Marine Sciences
University of Haifa
Mt. Carmel 31905,
Haifa, Israel
Email: [email protected]

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shilpa huddedar

surekha Satpute

Savitribai Phule Pune University

Ibrahim M Banat

University of Ulster

P K Dhakephalkar

Agharkar Research Institute

Universiti Malaysia Perlis (UniMAP)

Pattanathu Rahman

University of Portsmouth

Shubhrasekhar Chakraborty

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Papers by Kumar Saurav

Optimization and Characterization of Biosurfactant from Streptomyces

Springer eBooks, 2022

This search aims to study, isolation, characterization, and stability of biosurfactant isolated f... more This search aims to study, isolation, characterization, and stability of biosurfactant isolated from actinomycetes isolated from petroleum contaminated soil. Methods and Results: Optimizing the production of the biosurfactant from Streptomyces griseoplanus NRRL-ISP5009, SM1 was obtained on the 6 th day at 30°C, pH 7, 150 rpm, Glycerol yeast extract broth (GYEB) medium supplemented with cellulose, yeast extract and 1%NaCl. The stability of the biosurfactant produced was studied at the different temperature, pH and different concentration of NaCl. The produced biosurfactant was extracted and purified.

Biosynthetic Gene Cluster Analysis in Actinobacterial Genus Streptomyces

Springer eBooks, 2022

Quorum sensing signals from epibiont mediate the induction of bioactive peptides in mat-forming cyanobacteria Nostoc

bioRxiv (Cold Spring Harbor Laboratory), Apr 24, 2021

Screening of the Medicines for Malaria Venture Pandemic Response Box for Discovery of Antivirulent Drug against Pseudomonas aeruginosa

Microbiology spectrum, Dec 21, 2022

Resistance development and exhaustion of the arsenal of existing antibacterial agents urgently re... more Resistance development and exhaustion of the arsenal of existing antibacterial agents urgently require an alternative approach toward drug discovery. Herein, we report the screening of Medicines for Malaria Venture (MMV) Pandemic Response Box (PRB) through a cascade developed to streamline the potential compounds with antivirulent properties to combat an opportunistic pathogen, Pseudomonas aeruginosa. To find an agent suppressing the production of P. aeruginosa virulence factors, we assessed the potential of the compounds in PRB with quorum sensing inhibitory activity. Our approach led us to identify four compounds with significant inhibition of extracellular virulence factor production and biofilm formation. This provides an opportunity to expand and redirect the application of these data sets toward the development of a drug with unexplored target-based activity.

Quorum-Sensing Signals from Epibiont Mediate the Induction of Novel Microviridins in the Mat-Forming Cyanobacterial Genus <i>Nostoc</i>

mSphere, Aug 25, 2021

Quorum-sensing signals from epibiont mediate the induction of novel microviridins in the mat-form... more

Fatty Acid Substitutions Modulate the Cytotoxicity of Puwainaphycins/Minutissamides Isolated from the Baltic Sea Cyanobacterium <i>Nodularia harveyana</i> UHCC-0300

ACS omega, Mar 28, 2022

Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides tha... more Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides that exhibit high structural variability and possess antifungal and cytotoxic activities. While only a minor variation can be found in the amino acid composition of the peptide cycle, the fatty acid (FA) moiety varies largely. The effect of FA functionalization on the bioactivity of PUW/MIN chemical variants is poorly understood. A rapid and selective liquid chromatography−mass spectrometry-based method led us to identify 13 PUW/MIN (1−13) chemical variants from the benthic cyanobacterium Nodularia harveyana strain UHCC-0300 from the Baltic Sea. Five new variants identified were designated as PUW H (1), PUW I (2), PUW J (4), PUW K (10), and PUW L (13) and varied slightly in the peptidic core composition, but a larger variation was observed in the oxo-, chloro-, and hydroxy-substitutions on the FA moiety. To address the effect of FA substitution on the cytotoxic effect, the major variants (3 and 5−11) together with four other PUW/MIN variants (14−17) previously isolated were included in the study. The data obtained showed that hydroxylation of the FA moiety abolishes the cytotoxicity or significantly reduces it when compared with the oxo-substituted C 18-FA (compounds 5−8). The oxo-substitution had only a minor effect on the cytotoxicity of the compound when compared to variants bearing no substitution. The activity of PUW/ MIN variants with chlorinated FA moieties varied depending on the position of the chlorine atom on the FA chain. This study also shows that variation in the amino acids distant from the FA moiety (position 4−8 of the peptide cycle) does not play an important role in determining the cytotoxicity of the compound. These findings confirmed that the lipophilicity of FA is essential to maintain the cytotoxicity of PUW/MIN lipopeptides. Further, a 63 kb puwainaphycin biosynthetic gene cluster from a draft genome of the N. harveyana strain UHCC-0300 was identified. This pathway encoded two specific lipoinitiation mechanisms as well as enzymes needed for the modification of the FA moiety. Examination on biosynthetic gene clusters and the structural variability of the produced PUW/MIN suggested different mechanisms of fatty-acyl-AMP ligase cooperation with accessory enzymes leading to a new set of PUW/MIN variants bearing differently substituted FA.

Draft Genome Sequence of Terrestrial Streptomyces sp. Strain VITNK9, Isolated from Vellore, Tamil Nadu, India, Exhibiting Antagonistic Activity against Fish Pathogens

Microbiology resource announcements, Jan 7, 2021

Ishaque, and Ilia Burgsdorf contributed equally to this work. Author order was determined on the ... more

Nanoparticles Impregnated Wound Dressing Material and Its Mechanistic Insight for Chronic Wound Healing: Recent Progress

This article is an open access article distributed under the terms and conditions of the Creative... more

Co-existence of Quorum Sensing and Quorum Sensing Inhibitory Compounds in Marine Sponge Sarcotragus spinosulus

Marine sponges, a well documented prolific source of natural products, harbors numerous microbial... more Marine sponges, a well documented prolific source of natural products, harbors numerous microbial communities believed to possess N-acyl homoserine lactones (AHLs) mediated Quorum sensing (QS) as one of the mechanisms of interaction. Bacteria and eukaryotic organisms are known to produce molecules that can interfere with QS signaling, thus affecting microbial genetic regulation and function. In the present study, we established the potential for production of both QS signal molecules as well as QS interfering molecules (QSI) in the same sponge species Sarcotragus spinosulus. A total of eighteen saturated acyl chain AHLs were identified along with six putative unsaturated acyl chain AHLs. Bioassay guided purification led to the isolation of two brominated metabolites with QS-interfering activity. The structures of these compounds were elucidated by comparative spectral analysis of 1HNMR and HR-MS data and was identified as 3-Br-N-methyltyramine (1) and 5,6-dibromo-N,N-dimethyltryptam...

Draft Genome Sequence of Terrestrial Streptomyces sp. Strain VITNK9, Isolated from Vellore, Tamil Nadu, India, Exhibiting Antagonistic Activity against Fish Pathogens

Microbiology Resource Announcements, 2021

We report the draft genome sequence of Streptomyces sp. strain VITNK9, isolated from a soil sampl... more

Biological and Pharmacological Potential of Xylitol: A Molecular Insight of Unique Metabolism

Foods, 2020

Xylitol is a white crystalline, amorphous sugar alcohol and low-calorie sweetener. Xylitol preven... more Xylitol is a white crystalline, amorphous sugar alcohol and low-calorie sweetener. Xylitol prevents demineralization of teeth and bones, otitis media infection, respiratory tract infections, inflammation and cancer progression. NADPH generated in xylitol metabolism aid in the treatment of glucose-6-phosphate deficiency-associated hemolytic anemia. Moreover, it has a negligible effect on blood glucose and plasma insulin levels due to its unique metabolism. Its diverse applications in pharmaceuticals, cosmetics, food and polymer industries fueled its market growth and made it one of the top 12 bio-products. Recently, xylitol has also been used as a drug carrier due to its high permeability and non-toxic nature. However, it become a challenge to fulfil the rapidly increasing market demand of xylitol. Xylitol is present in fruit and vegetables, but at very low concentrations, which is not adequate to satisfy the consumer demand. With the passage of time, other methods including chemical...

Plakofuranolactone as a Quorum Quenching Agent from the Indonesian Sponge Plakortis cf. lita

Marine drugs, Jan 28, 2017

There is an urgent need for novel strategies to fight drug resistance and multi-drug resistance. ... more There is an urgent need for novel strategies to fight drug resistance and multi-drug resistance. As an alternative to the classic antibiotic therapy, attenuation of the bacteria virulence affecting their Quorum sensing (QS) system is a promising approach. Quorum sensing (QS) is a genetic regulation system that allows bacteria to communicate with each other and coordinate group behaviors. A new γ-lactone that is capable of inhibiting the LasI/R QS system, plakofuranolactone (1), was discovered in the extract of the marine sponge Plakortis cf. lita, and its structure, including absolute configuration, was determined by NMR spectroscopy, MS spectrometry, and quantum-mechanical prediction of optical rotation. The quorum quenching activity of plakofuranolactone was evaluated using reporter gene assays for long- and short-chain signals (E. coli pSB1075, E. coli pSB401, and C. violeaceum CV026) and was confirmed by measuring the total protease activity (a virulence factor which is under co...

Quorum Sensing Inhibitors from the Sea Discovered Using Bacterial N-acyl-homoserine Lactone-Based Biosensors

Marine Drugs, 2017

Marine natural products with antibiotic activity have been a rich source of drug discovery; howev... more Marine natural products with antibiotic activity have been a rich source of drug discovery; however, the emergence of antibiotic-resistant bacterial strains has turned attention towards the discovery of alternative innovative strategies to combat pathogens. In many pathogenic bacteria, the expression of virulence factors is under the regulation of quorum sensing (QS). QS inhibitors (QSIs) present a promising alternative or potential synergistic treatment since they disrupt the signaling pathway used for intra-and interspecies coordination of expression of virulence factors. This review covers the set of molecules showing QSI activity that were isolated from marine organisms, including plants (algae), animals (sponges, cnidarians, and bryozoans), and microorganisms (bacteria, fungi, and cyanobacteria). The compounds found and the methods used for their isolation are the emphasis of this review.

Isolation and screening of bioactive compound from actinomycetes isolated from salt pan of Marakanam district of the state Tamil Nadu, India

A B S T RA CT Natural products either the source of the inspiration for a significant proportion ... more A B S T RA CT Natural products either the source of the inspiration for a significant proportion of the new small molecule chemical entities introduced as drugs. Actinomycetes are the largest antibiotic producing genus in the microbial world discovered so far. The number of antimicrobial compounds reported from the different species of actinomycetes per year has increased almost exponentially for about two decades. As marine environment are different from terrestrial, it is concluded that marine actinomycetes might produce various types of novel bioactive compounds and enormous antibiotics. The objectives of this study is to isolate actinomycetes from salt pans of Marakanam to optimize and screen the production of secondary metabolites from the selected actinomycetes and to check the antimicrobial activity of these metabolites against pathogens. Out of 30 actinomycetes isolates Ros11 and Ros25 were screened and characterized based on antimicrobial properties. The secondary metabolites were extracted from Ros 11 and Ros 25 by chemical solvents, ethyl acetate and acetone. Using well diffusion method, it was observed that secondary metabolites of Ros 25 formed maximum inhibition zones, 10mm, 12mm and 15mm against Staphylococcus aureus and fungal pathogens Aspergillus niger and Aspergillus fumigates, respectively. The Ros 25 isolate could be the better candidate for the production of antibacterial and antifungal compounds.

Isolation, Genomic and Metabolomic Characterization of Streptomyces tendae VITAKN with Quorum Sensing Inhibitory Activity from Southern India

Streptomyces, being one of the most promising genera due to its ability to synthesize a variety o... more Streptomyces, being one of the most promising genera due to its ability to synthesize a variety of bioactive secondary metabolites of pharmaceutical interest, here studied in relation to its genomic and metabolomic potential. Coinciding with the increase in sequenced data, mining of bacterial genomes for biosynthetic gene clusters (BGCs) has become a routine component of natural product discovery. Herein, we describe the isolation and characterization of a Streptomyces tendae VITAKN with quorum sensing inhibitory activity (QSI) that was isolated from southern coastal parts of India. The nearly complete genome consists of 8,621,231bp with a GC content of 72.2%. Utilizing the BiG-SCAPE-CORASON platform, a sequence similarity network predicted from this strain was evaluated through sequence similarity analysis with the MIBiG database and existing 3,365 BGCs predicted by antiSMASH analysis of publicly available complete Streptomyces genomes. Crude extract analyzed on LC-HRMS/MS and Glob...

Silver Nanoparticles and Its Mechanistic Insight for Chronic Wound Healing: Review on Recent Progress

Molecules, Aug 30, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more

Isolation of MarineParacoccussp. Ss63 from the SpongeSarcotragussp. and Characterization of its Quorum-Sensing Chemical-Signaling Molecules by LC-MS/MS Analysis

Israel Journal of Chemistry, 2016

Gram-negative bacteria often use N-acyl homoserine lactones (AHLs) as quorum-sensing (QS) signal ... more Gram-negative bacteria often use N-acyl homoserine lactones (AHLs) as quorum-sensing (QS) signal molecules. The present study aimed to identify and characterize the production of AHLs by Paracoccus sp. Ss63, which was isolated from the Mediterranean sponge Sarcotragus sp. High performance liquid chromatography – high resolution tandem mass spectrometry (LC-HRMS/MS) provided evidence for the production, by Paracoccus sp. Ss63, of twelve saturated long-chain AHLs (3-OH-C10-HSL, 3-OH-C12-HSL, C10-HSL, 3-OH-C14-HSL, C12-HSL, 3-O-C16-HSL, 3-OH-C16-HSL, C14-HSL, 3-OH-C18-HSL, C16-HSL, 3-O-C18-HSL, and C18-HSL), along with four putative unsaturated long-chain AHLs (C10 : 1-HSL, 3-OH-C18 : 1-HSL, C16 : 1-HSL, and C18 : 1-HSL). The distribution of Paracoccus sp. Ss63 in different sponge species, as well as in seawater and marine sediment samples, suggests a mixed lifestyle for this bacterium, i.e., free-living and host-associated. The high pH of seawater is likely to inactivate the AHL signal molecules, and limit the possibility of AHLs to accumulate to the concentration required for QS-based gene regulation. We hypothesize that Paracoccus sp. Ss63 utilizes quorum sensing to sense and respond to the different environments it experiences, with an active QS only when found inside enclosed niches (host-associated and at lower pH).

Aspergillosis and its resistance: Marine natural products as future treatment

Synthetic and Natural Compounds, 2015

Fatty Acid Substitutions Modulate the Cytotoxicity of Puwainaphycins/Minutissamides Isolated from the Baltic Sea Cyanobacterium Nodularia harveyana UHCC-0300

Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides tha... more Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides that exhibit high structural variability and possess antifungal and cytotoxic activities. While only a minor variation can be found in the amino acid composition of the peptide cycle, the fatty acid (FA) moiety varies largely. The effect of FA functionalization on the bioactivity of PUW/MIN chemical variants is poorly understood. A rapid and selective liquid chromatography−mass spectrometry-based method led us to identify 13 PUW/MIN (1−13) chemical variants from the benthic cyanobacterium Nodularia harveyana strain UHCC-0300 from the Baltic Sea. Five new variants identified were designated as PUW H (1), PUW I (2), PUW J (4), PUW K (10), and PUW L (13) and varied slightly in the peptidic core composition, but a larger variation was observed in the oxo-, chloro-, and hydroxy-substitutions on the FA moiety. To address the effect of FA substitution on the cytotoxic effect, the major variants (3 and 5−11) together with four other PUW/MIN variants (14−17) previously isolated were included in the study. The data obtained showed that hydroxylation of the FA moiety abolishes the cytotoxicity or significantly reduces it when compared with the oxo-substituted C 18-FA (compounds 5−8). The oxo-substitution had only a minor effect on the cytotoxicity of the compound when compared to variants bearing no substitution. The activity of PUW/ MIN variants with chlorinated FA moieties varied depending on the position of the chlorine atom on the FA chain. This study also shows that variation in the amino acids distant from the FA moiety (position 4−8 of the peptide cycle) does not play an important role in determining the cytotoxicity of the compound. These findings confirmed that the lipophilicity of FA is essential to maintain the cytotoxicity of PUW/MIN lipopeptides. Further, a 63 kb puwainaphycin biosynthetic gene cluster from a draft genome of the N. harveyana strain UHCC-0300 was identified. This pathway encoded two specific lipoinitiation mechanisms as well as enzymes needed for the modification of the FA moiety. Examination on biosynthetic gene clusters and the structural variability of the produced PUW/MIN suggested different mechanisms of fatty-acyl-AMP ligase cooperation with accessory enzymes leading to a new set of PUW/MIN variants bearing differently substituted FA.

Insight into Unprecedented Diversity of Cyanopeptides in Eutrophic Ponds Using an MS/MS Networking Approach

Toxins, 2020

Man-made shallow fishponds in the Czech Republic have been facing high eutrophication since the 1... more Man-made shallow fishponds in the Czech Republic have been facing high eutrophication since the 1950s. Anthropogenic eutrophication and feeding of fish have strongly affected the physicochemical properties of water and its aquatic community composition, leading to harmful algal bloom formation. In our current study, we characterized the phytoplankton community across three eutrophic ponds to assess the phytoplankton dynamics during the vegetation season. We microscopically identified and quantified 29 cyanobacterial taxa comprising non-toxigenic and toxigenic species. Further, a detailed cyanopeptides (CNPs) profiling was performed using molecular networking analysis of liquid chromatography-tandem mass spectrometry (LC-MS/MS) data coupled with a dereplication strategy. This MS networking approach, coupled with dereplication, on the online global natural product social networking (GNPS) web platform led us to putatively identify forty CNPs: fourteen anabaenopeptins, ten microcystins...

Optimization and Characterization of Biosurfactant from Streptomyces

Springer eBooks, 2022

This search aims to study, isolation, characterization, and stability of biosurfactant isolated f... more This search aims to study, isolation, characterization, and stability of biosurfactant isolated from actinomycetes isolated from petroleum contaminated soil. Methods and Results: Optimizing the production of the biosurfactant from Streptomyces griseoplanus NRRL-ISP5009, SM1 was obtained on the 6 th day at 30°C, pH 7, 150 rpm, Glycerol yeast extract broth (GYEB) medium supplemented with cellulose, yeast extract and 1%NaCl. The stability of the biosurfactant produced was studied at the different temperature, pH and different concentration of NaCl. The produced biosurfactant was extracted and purified.

Biosynthetic Gene Cluster Analysis in Actinobacterial Genus Streptomyces

Springer eBooks, 2022

Quorum sensing signals from epibiont mediate the induction of bioactive peptides in mat-forming cyanobacteria Nostoc

bioRxiv (Cold Spring Harbor Laboratory), Apr 24, 2021

Screening of the Medicines for Malaria Venture Pandemic Response Box for Discovery of Antivirulent Drug against Pseudomonas aeruginosa

Microbiology spectrum, Dec 21, 2022

Resistance development and exhaustion of the arsenal of existing antibacterial agents urgently re... more Resistance development and exhaustion of the arsenal of existing antibacterial agents urgently require an alternative approach toward drug discovery. Herein, we report the screening of Medicines for Malaria Venture (MMV) Pandemic Response Box (PRB) through a cascade developed to streamline the potential compounds with antivirulent properties to combat an opportunistic pathogen, Pseudomonas aeruginosa. To find an agent suppressing the production of P. aeruginosa virulence factors, we assessed the potential of the compounds in PRB with quorum sensing inhibitory activity. Our approach led us to identify four compounds with significant inhibition of extracellular virulence factor production and biofilm formation. This provides an opportunity to expand and redirect the application of these data sets toward the development of a drug with unexplored target-based activity.

Quorum-Sensing Signals from Epibiont Mediate the Induction of Novel Microviridins in the Mat-Forming Cyanobacterial Genus <i>Nostoc</i>

mSphere, Aug 25, 2021

Quorum-sensing signals from epibiont mediate the induction of novel microviridins in the mat-form... more

Fatty Acid Substitutions Modulate the Cytotoxicity of Puwainaphycins/Minutissamides Isolated from the Baltic Sea Cyanobacterium <i>Nodularia harveyana</i> UHCC-0300

ACS omega, Mar 28, 2022

Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides tha... more Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides that exhibit high structural variability and possess antifungal and cytotoxic activities. While only a minor variation can be found in the amino acid composition of the peptide cycle, the fatty acid (FA) moiety varies largely. The effect of FA functionalization on the bioactivity of PUW/MIN chemical variants is poorly understood. A rapid and selective liquid chromatography−mass spectrometry-based method led us to identify 13 PUW/MIN (1−13) chemical variants from the benthic cyanobacterium Nodularia harveyana strain UHCC-0300 from the Baltic Sea. Five new variants identified were designated as PUW H (1), PUW I (2), PUW J (4), PUW K (10), and PUW L (13) and varied slightly in the peptidic core composition, but a larger variation was observed in the oxo-, chloro-, and hydroxy-substitutions on the FA moiety. To address the effect of FA substitution on the cytotoxic effect, the major variants (3 and 5−11) together with four other PUW/MIN variants (14−17) previously isolated were included in the study. The data obtained showed that hydroxylation of the FA moiety abolishes the cytotoxicity or significantly reduces it when compared with the oxo-substituted C 18-FA (compounds 5−8). The oxo-substitution had only a minor effect on the cytotoxicity of the compound when compared to variants bearing no substitution. The activity of PUW/ MIN variants with chlorinated FA moieties varied depending on the position of the chlorine atom on the FA chain. This study also shows that variation in the amino acids distant from the FA moiety (position 4−8 of the peptide cycle) does not play an important role in determining the cytotoxicity of the compound. These findings confirmed that the lipophilicity of FA is essential to maintain the cytotoxicity of PUW/MIN lipopeptides. Further, a 63 kb puwainaphycin biosynthetic gene cluster from a draft genome of the N. harveyana strain UHCC-0300 was identified. This pathway encoded two specific lipoinitiation mechanisms as well as enzymes needed for the modification of the FA moiety. Examination on biosynthetic gene clusters and the structural variability of the produced PUW/MIN suggested different mechanisms of fatty-acyl-AMP ligase cooperation with accessory enzymes leading to a new set of PUW/MIN variants bearing differently substituted FA.

Draft Genome Sequence of Terrestrial Streptomyces sp. Strain VITNK9, Isolated from Vellore, Tamil Nadu, India, Exhibiting Antagonistic Activity against Fish Pathogens

Microbiology resource announcements, Jan 7, 2021

Ishaque, and Ilia Burgsdorf contributed equally to this work. Author order was determined on the ... more

Nanoparticles Impregnated Wound Dressing Material and Its Mechanistic Insight for Chronic Wound Healing: Recent Progress

This article is an open access article distributed under the terms and conditions of the Creative... more

Co-existence of Quorum Sensing and Quorum Sensing Inhibitory Compounds in Marine Sponge Sarcotragus spinosulus

Marine sponges, a well documented prolific source of natural products, harbors numerous microbial... more Marine sponges, a well documented prolific source of natural products, harbors numerous microbial communities believed to possess N-acyl homoserine lactones (AHLs) mediated Quorum sensing (QS) as one of the mechanisms of interaction. Bacteria and eukaryotic organisms are known to produce molecules that can interfere with QS signaling, thus affecting microbial genetic regulation and function. In the present study, we established the potential for production of both QS signal molecules as well as QS interfering molecules (QSI) in the same sponge species Sarcotragus spinosulus. A total of eighteen saturated acyl chain AHLs were identified along with six putative unsaturated acyl chain AHLs. Bioassay guided purification led to the isolation of two brominated metabolites with QS-interfering activity. The structures of these compounds were elucidated by comparative spectral analysis of 1HNMR and HR-MS data and was identified as 3-Br-N-methyltyramine (1) and 5,6-dibromo-N,N-dimethyltryptam...

Draft Genome Sequence of Terrestrial Streptomyces sp. Strain VITNK9, Isolated from Vellore, Tamil Nadu, India, Exhibiting Antagonistic Activity against Fish Pathogens

Microbiology Resource Announcements, 2021

We report the draft genome sequence of Streptomyces sp. strain VITNK9, isolated from a soil sampl... more

Biological and Pharmacological Potential of Xylitol: A Molecular Insight of Unique Metabolism

Foods, 2020

Xylitol is a white crystalline, amorphous sugar alcohol and low-calorie sweetener. Xylitol preven... more Xylitol is a white crystalline, amorphous sugar alcohol and low-calorie sweetener. Xylitol prevents demineralization of teeth and bones, otitis media infection, respiratory tract infections, inflammation and cancer progression. NADPH generated in xylitol metabolism aid in the treatment of glucose-6-phosphate deficiency-associated hemolytic anemia. Moreover, it has a negligible effect on blood glucose and plasma insulin levels due to its unique metabolism. Its diverse applications in pharmaceuticals, cosmetics, food and polymer industries fueled its market growth and made it one of the top 12 bio-products. Recently, xylitol has also been used as a drug carrier due to its high permeability and non-toxic nature. However, it become a challenge to fulfil the rapidly increasing market demand of xylitol. Xylitol is present in fruit and vegetables, but at very low concentrations, which is not adequate to satisfy the consumer demand. With the passage of time, other methods including chemical...

Plakofuranolactone as a Quorum Quenching Agent from the Indonesian Sponge Plakortis cf. lita

Marine drugs, Jan 28, 2017

There is an urgent need for novel strategies to fight drug resistance and multi-drug resistance. ... more There is an urgent need for novel strategies to fight drug resistance and multi-drug resistance. As an alternative to the classic antibiotic therapy, attenuation of the bacteria virulence affecting their Quorum sensing (QS) system is a promising approach. Quorum sensing (QS) is a genetic regulation system that allows bacteria to communicate with each other and coordinate group behaviors. A new γ-lactone that is capable of inhibiting the LasI/R QS system, plakofuranolactone (1), was discovered in the extract of the marine sponge Plakortis cf. lita, and its structure, including absolute configuration, was determined by NMR spectroscopy, MS spectrometry, and quantum-mechanical prediction of optical rotation. The quorum quenching activity of plakofuranolactone was evaluated using reporter gene assays for long- and short-chain signals (E. coli pSB1075, E. coli pSB401, and C. violeaceum CV026) and was confirmed by measuring the total protease activity (a virulence factor which is under co...

Quorum Sensing Inhibitors from the Sea Discovered Using Bacterial N-acyl-homoserine Lactone-Based Biosensors

Marine Drugs, 2017

Marine natural products with antibiotic activity have been a rich source of drug discovery; howev... more Marine natural products with antibiotic activity have been a rich source of drug discovery; however, the emergence of antibiotic-resistant bacterial strains has turned attention towards the discovery of alternative innovative strategies to combat pathogens. In many pathogenic bacteria, the expression of virulence factors is under the regulation of quorum sensing (QS). QS inhibitors (QSIs) present a promising alternative or potential synergistic treatment since they disrupt the signaling pathway used for intra-and interspecies coordination of expression of virulence factors. This review covers the set of molecules showing QSI activity that were isolated from marine organisms, including plants (algae), animals (sponges, cnidarians, and bryozoans), and microorganisms (bacteria, fungi, and cyanobacteria). The compounds found and the methods used for their isolation are the emphasis of this review.

Isolation and screening of bioactive compound from actinomycetes isolated from salt pan of Marakanam district of the state Tamil Nadu, India

A B S T RA CT Natural products either the source of the inspiration for a significant proportion ... more A B S T RA CT Natural products either the source of the inspiration for a significant proportion of the new small molecule chemical entities introduced as drugs. Actinomycetes are the largest antibiotic producing genus in the microbial world discovered so far. The number of antimicrobial compounds reported from the different species of actinomycetes per year has increased almost exponentially for about two decades. As marine environment are different from terrestrial, it is concluded that marine actinomycetes might produce various types of novel bioactive compounds and enormous antibiotics. The objectives of this study is to isolate actinomycetes from salt pans of Marakanam to optimize and screen the production of secondary metabolites from the selected actinomycetes and to check the antimicrobial activity of these metabolites against pathogens. Out of 30 actinomycetes isolates Ros11 and Ros25 were screened and characterized based on antimicrobial properties. The secondary metabolites were extracted from Ros 11 and Ros 25 by chemical solvents, ethyl acetate and acetone. Using well diffusion method, it was observed that secondary metabolites of Ros 25 formed maximum inhibition zones, 10mm, 12mm and 15mm against Staphylococcus aureus and fungal pathogens Aspergillus niger and Aspergillus fumigates, respectively. The Ros 25 isolate could be the better candidate for the production of antibacterial and antifungal compounds.

Isolation, Genomic and Metabolomic Characterization of Streptomyces tendae VITAKN with Quorum Sensing Inhibitory Activity from Southern India

Streptomyces, being one of the most promising genera due to its ability to synthesize a variety o... more Streptomyces, being one of the most promising genera due to its ability to synthesize a variety of bioactive secondary metabolites of pharmaceutical interest, here studied in relation to its genomic and metabolomic potential. Coinciding with the increase in sequenced data, mining of bacterial genomes for biosynthetic gene clusters (BGCs) has become a routine component of natural product discovery. Herein, we describe the isolation and characterization of a Streptomyces tendae VITAKN with quorum sensing inhibitory activity (QSI) that was isolated from southern coastal parts of India. The nearly complete genome consists of 8,621,231bp with a GC content of 72.2%. Utilizing the BiG-SCAPE-CORASON platform, a sequence similarity network predicted from this strain was evaluated through sequence similarity analysis with the MIBiG database and existing 3,365 BGCs predicted by antiSMASH analysis of publicly available complete Streptomyces genomes. Crude extract analyzed on LC-HRMS/MS and Glob...

Silver Nanoparticles and Its Mechanistic Insight for Chronic Wound Healing: Review on Recent Progress

Molecules, Aug 30, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more

Isolation of MarineParacoccussp. Ss63 from the SpongeSarcotragussp. and Characterization of its Quorum-Sensing Chemical-Signaling Molecules by LC-MS/MS Analysis

Israel Journal of Chemistry, 2016

Gram-negative bacteria often use N-acyl homoserine lactones (AHLs) as quorum-sensing (QS) signal ... more Gram-negative bacteria often use N-acyl homoserine lactones (AHLs) as quorum-sensing (QS) signal molecules. The present study aimed to identify and characterize the production of AHLs by Paracoccus sp. Ss63, which was isolated from the Mediterranean sponge Sarcotragus sp. High performance liquid chromatography – high resolution tandem mass spectrometry (LC-HRMS/MS) provided evidence for the production, by Paracoccus sp. Ss63, of twelve saturated long-chain AHLs (3-OH-C10-HSL, 3-OH-C12-HSL, C10-HSL, 3-OH-C14-HSL, C12-HSL, 3-O-C16-HSL, 3-OH-C16-HSL, C14-HSL, 3-OH-C18-HSL, C16-HSL, 3-O-C18-HSL, and C18-HSL), along with four putative unsaturated long-chain AHLs (C10 : 1-HSL, 3-OH-C18 : 1-HSL, C16 : 1-HSL, and C18 : 1-HSL). The distribution of Paracoccus sp. Ss63 in different sponge species, as well as in seawater and marine sediment samples, suggests a mixed lifestyle for this bacterium, i.e., free-living and host-associated. The high pH of seawater is likely to inactivate the AHL signal molecules, and limit the possibility of AHLs to accumulate to the concentration required for QS-based gene regulation. We hypothesize that Paracoccus sp. Ss63 utilizes quorum sensing to sense and respond to the different environments it experiences, with an active QS only when found inside enclosed niches (host-associated and at lower pH).

Aspergillosis and its resistance: Marine natural products as future treatment

Synthetic and Natural Compounds, 2015

Fatty Acid Substitutions Modulate the Cytotoxicity of Puwainaphycins/Minutissamides Isolated from the Baltic Sea Cyanobacterium Nodularia harveyana UHCC-0300

Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides tha... more Puwainaphycins (PUW) and minutissamides (MIN) are structurally homologous cyclic lipopeptides that exhibit high structural variability and possess antifungal and cytotoxic activities. While only a minor variation can be found in the amino acid composition of the peptide cycle, the fatty acid (FA) moiety varies largely. The effect of FA functionalization on the bioactivity of PUW/MIN chemical variants is poorly understood. A rapid and selective liquid chromatography−mass spectrometry-based method led us to identify 13 PUW/MIN (1−13) chemical variants from the benthic cyanobacterium Nodularia harveyana strain UHCC-0300 from the Baltic Sea. Five new variants identified were designated as PUW H (1), PUW I (2), PUW J (4), PUW K (10), and PUW L (13) and varied slightly in the peptidic core composition, but a larger variation was observed in the oxo-, chloro-, and hydroxy-substitutions on the FA moiety. To address the effect of FA substitution on the cytotoxic effect, the major variants (3 and 5−11) together with four other PUW/MIN variants (14−17) previously isolated were included in the study. The data obtained showed that hydroxylation of the FA moiety abolishes the cytotoxicity or significantly reduces it when compared with the oxo-substituted C 18-FA (compounds 5−8). The oxo-substitution had only a minor effect on the cytotoxicity of the compound when compared to variants bearing no substitution. The activity of PUW/ MIN variants with chlorinated FA moieties varied depending on the position of the chlorine atom on the FA chain. This study also shows that variation in the amino acids distant from the FA moiety (position 4−8 of the peptide cycle) does not play an important role in determining the cytotoxicity of the compound. These findings confirmed that the lipophilicity of FA is essential to maintain the cytotoxicity of PUW/MIN lipopeptides. Further, a 63 kb puwainaphycin biosynthetic gene cluster from a draft genome of the N. harveyana strain UHCC-0300 was identified. This pathway encoded two specific lipoinitiation mechanisms as well as enzymes needed for the modification of the FA moiety. Examination on biosynthetic gene clusters and the structural variability of the produced PUW/MIN suggested different mechanisms of fatty-acyl-AMP ligase cooperation with accessory enzymes leading to a new set of PUW/MIN variants bearing differently substituted FA.

Insight into Unprecedented Diversity of Cyanopeptides in Eutrophic Ponds Using an MS/MS Networking Approach

Toxins, 2020

Man-made shallow fishponds in the Czech Republic have been facing high eutrophication since the 1... more Man-made shallow fishponds in the Czech Republic have been facing high eutrophication since the 1950s. Anthropogenic eutrophication and feeding of fish have strongly affected the physicochemical properties of water and its aquatic community composition, leading to harmful algal bloom formation. In our current study, we characterized the phytoplankton community across three eutrophic ponds to assess the phytoplankton dynamics during the vegetation season. We microscopically identified and quantified 29 cyanobacterial taxa comprising non-toxigenic and toxigenic species. Further, a detailed cyanopeptides (CNPs) profiling was performed using molecular networking analysis of liquid chromatography-tandem mass spectrometry (LC-MS/MS) data coupled with a dereplication strategy. This MS networking approach, coupled with dereplication, on the online global natural product social networking (GNPS) web platform led us to putatively identify forty CNPs: fourteen anabaenopeptins, ten microcystins...