Bioactive Microbial Metabolites Research Articles

Enhancing biolipid production and self-flocculation of Chlorella vulgaris by extracellular polymeric substances from granular sludge with CO2 addition: Microscopic mechanism of microalgae-bacteria symbiosis

Microalgae-bacteria symbiotic systems were known to have great potential for simultaneous water purification and resource recovery, among them, microalgae-bacteria biofilm/granules have attracted much attention due to its excellent effluent quality and convenient biomass recovery. However, the effect of bacteria with attached-growth mode on microalgae, which has more significance for bioresource utilization, has been historically ignored. Thus, this study attempted to explore the responses of C. vulgaris to extracellular polymeric substances (EPS) extracted from aerobic granular sludge (AGS), for enhancing the understanding of microscopic mechanism of attached microalgae-bacteria symbiosis. Results showed that the performance of C. vulgaris was effectively boosted with AGS-EPS treatment at 12–16 mg TOC/L, highest biomass production (0.32±0.01 g/L), lipid accumulation (44.33±5.69%) and flocculation ability (20.83±0.21%) were achieved. These phenotypes were promoted associated with bioactive microbial metabolites in AGS-EPS (N-acyl-homoserine lactones, humic acid and tryptophan). Furthermore, the addition of CO2 triggered carbon flow into the storage of lipids in C. vulgaris, and the synergistic effect of AGS-EPS and CO2 for improving microalgal flocculation ability was disclosed. Transcriptomic analysis further revealed up-regulation of synthesis pathways for fatty acid and triacylglycerol that was triggered by AGS-EPS. And within the context of CO2 addition, AGS-EPS substantially upregulated the expression of aromatic protein encoding genes, which further enhanced the self-flocculation of C. vulgaris. These findings provide novel insights into the microscopic mechanism of microalgae-bacteria symbiosis, and bring new enlightenment to wastewater valorization and carbon-neutral operation of wastewater treatment plants based on the symbiotic biofilm/biogranules system.

Bioactive Microbial Metabolites in Cancer Therapeutics: Mining, Repurposing, and Their Molecular Targets.

The persistence and resurgence of cancer, characterized by abnormal cell growth and differentiation, continues to be a serious public health concern critically affecting public health, social life, and the global economy. Hundreds of putative drug molecules of synthetic and natural origin were approved for anticancer therapy in the last few decades. Although conventional anticancer treatment strategies have promising aspects, several factors such as their limitations, drug resistance, and side effects associated with them demand more effort in repositioning or developing novel therapeutic regimens. The rich heritage of microbial bioactive components remains instrumental in providing novel avenues for cancer therapeutics. Actinobacteria, Firmicutes, and fungi have a plethora of bioactive compounds, which received attention for their efficacy in cancer treatment targeting different pathways responsible for abnormal cell growth and differentiation. Yet the full potential remains underexplored to date, and novel compounds from such microbes are reported regularly. In addition, the advent of computational tools has further augmented the mining of microbial secondary metabolites and identifying their molecular targets in cancer cells. Furthermore, the drug-repurposing strategy has facilitated the use of approved drugs of microbial origin in regulating cancer cell growth and progression. The wide diversity of microbial compounds, different mining approaches, and multiple modes of action warrant further investigations on the current status of microbial metabolites in cancer therapeutics. Hence, in this review, we have critically discussed the untapped potential of microbial products in mitigating cancer progression. The review also summarizes the impact of drug repurposing in cancer therapy and discusses the novel avenues for future therapeutic drug development against cancer.

γ-Aromatic Butenolides of Microbial Source - A Review of Their Structures, Biological Activities and Biosynthesis.

γ-Aromatic butenolides (γ-AB) are an important type of structures found in many bioactive microbial secondary metabolites (SMs). γ-AB refer to a group of natural products (NPs) containing five-membered (unsaturated) lactones with 3-phenyl and 4-benzyl substituents. Their wide-range biological activities have inspired pharmaceutical chemists to explore its biosynthesis mechanisms and design strategies to construct the γ-AB skeleton. Recently, there are a great deal of interesting research progress on the structures, biological activities and biosynthesis of γ-AB. This review will focus on these aspects and summarize the important achievements of γ-AB from 1975 to 2021.

Host-microbe interactions and outcomes in multiple myeloma and hematopoietic stem cell transplantation.

Microbiota are essential to normal immune development and there is growing recognition of its importance to human health and disease and deepening understanding of the complexity of host-microbe interactions in the human gut and other tissues. Commensal microbes not only can influence host immunity locally through impacts of bioactive microbial metabolites and direct interactions with epithelial cells and innate immune receptors but also can exert systemic immunomodulatory effects via impacts on host immune cells capable of trafficking beyond the gut. Emerging data suggest microbiota influence the development of multiple myeloma (MM), a malignancy of the immune system derived from immunoglobulin-producing bone marrow plasma cells, through the promotion of inflammation. Superior treatment outcomes for MM correlate with a higher abundance of commensal microbiota capable of influencing inflammatory responses through the production of butyrate. In patients with hematologic malignancies, higher levels of diversity of the gut microbiota correlate with superior outcomes after hematopoietic stem cell transplantation. Correlative data support the impact of commensal microbiota on survival, risk of infection, disease relapse, and graft-versus-host disease (GVHD) after transplant. In this review, we will discuss the current understanding of the role of host-microbe interactions and the inflammatory tumor microenvironment of multiple myeloma, discuss data describing the key role of microbiota in hematopoietic stem cell transplantation for treatment of hematologic malignancies, and highlight several possible concepts for interventions directed at the gut microbiota to influence treatment outcomes.

Degradation of black tea theaflavin through C-ring cleavage by gut microbiota

Increasing evidence has shown that gut microbiota plays important roles in metabolizing large molecular polyphenols to bioavailable and bioactive microbial metabolites. Theaflavin (TF) is one of the major color compounds in black tea and has demonstrated anti-inflammation, antioxidant, and anticancer effects properties. However, little is known about the metabolism of TF by gut microbiota in vivo. In this study, following the administration of TF to mice, the C-ring cleavage metabolites, dihydro- and tetrahydro-theaflavin (DH-TF and TH-TF) were detected in mouse feces by LC-MS and validated by authentic standards from in situ chemical reaction. The observation of the C-ring cleavage metabolites in TF-treated conventionalized mice but not in germ-free (GF) mice confirmed the role of gut microbiota in cleaving the C-rings of TF. The detection of DH-TF from the anaerobic incubation of TF with catechin-converting gut bacteria, Eggerthella lenta (Eggerth), suggested that the microbes with the capacity to cleave the C-ring of catechins were able to metabolize TF following the same mechanism. Additionally, three small phenolic metabolites were detected in mouse feces, and one of them was primarily detected in SPF mice not GF mice, which revealed that TF, subsequent to the cleaved C-ring, can be further metabolized into smaller phenolic metabolites by gut microbiota. Dose-dependent production of these metabolites were observed from the administration of 100 mg/kg to 400 mg/kg body weight of TF. In conclusion, gut microbiota can metabolize TF to the open-ring metabolites and the phenolic metabolites through the C-ring cleavage in mice.

Characterization of Bioactive Compounds from the Red Sea Tunicate- Derived Fungus Penicillium commune DY004

Abstract: As a part of our ongoing interest to identify bioactive microbial secondary metabolites, the Red Sea tunicate derived Penicillium commune DY004 was investigated. A new dipeptide, penicillizine A (1) together with cyclo(L-Pro-L-Phe) (2), meleagrin (3), α-cyclopiazonic acid (4) and N-(4-hydroxyphenethyl)acetamide (5) was isolated from the ethyl acetate extract of the cultures of the fungus. The structural determinations of 1-5 were supported by interpretation of their one- and two-dimensional nuclear magnetic resonance (NMR) and mass spectrometry (MS) data. In the evaluation of the compounds for their effects against three human tumorous cell lines, meleagrin (3) and α-cyclopiazonic acid (4) displayed the highest and potent activity against HeLa, U373 glioblastoma and MDA-MB-231 cell lines down up to 3.1 μg/mL. These results suggest that marine fungi are a copious source of drug leads with therapeutic potential. Meleagrin and α- cyclopiazonic acid could be used as potential scaffolds for the development of new and more effective drug leads.

Luteapyrone, a Novel ƴ-Pyrone Isolated from the Filamentous Fungus Metapochonia lutea.

In the process of screening for new bioactive microbial metabolites we found a novel ƴ-pyrone derivative for which we propose the trivial name luteapyrone, in a recently described microscopic filamentous fungus, Metapochonia lutea BiMM-F96/DF4. The compound was isolated from the culture extract of the fungus grown on modified yeast extract sucrose medium by means of flash chromatography followed by preparative HPLC. The chemical structure was elucidated by NMR and LC-MS. The new compound was found to be non-cytotoxic against three mammalian cell lines (HEK 263, KB-3.1 and Caco-2). Similarly, no antimicrobial activity was observed in tested microorganisms (gram positive and negative bacteria, yeast and fungi).

Neuropsychiatric Ramifications of COVID-19: Short-Chain Fatty Acid Deficiency and Disturbance of Microbiota-Gut-Brain Axis Signaling.

COVID-19-associated neuropsychiatric complications are soaring. There is an urgent need to understand the link between COVID-19 and neuropsychiatric disorders. To that end, this article addresses the premise that SARS-CoV-2 infection results in gut dysbiosis and an altered microbiota-gut-brain (MGB) axis that in turn contributes to the neuropsychiatric ramifications of COVID-19. Altered MGB axis activity has been implicated independently as a risk of neuropsychiatric disorders. A review of the changes in gut microbiota composition in individual psychiatric and neurological disorders and gut microbiota in COVID-19 patients revealed a shared “microbial signature” characterized by a lower microbial diversity and richness and a decrease in health-promoting anti-inflammatory commensal bacteria accompanied by an increase in opportunistic proinflammatory pathogens. Notably, there was a decrease in short-chain fatty acid (SCFA) producing bacteria. SCFAs are key bioactive microbial metabolites with anti-inflammatory functions and have been recognized as a critical signaling pathway in the MGB axis. SCFA deficiency is associated with brain inflammation, considered a cardinal feature of neuropsychiatric disorders. The link between SARS-CoV-2 infection, gut dysbiosis, and altered MGB axis is further supported by COVID-19-associated gastrointestinal symptoms, a high number of SARS-CoV-2 receptors, angiotensin-cleaving enzyme-2 (ACE-2) in the gut, and viral presence in the fecal matter. The binding of SARS-CoV-2 to the receptor results in ACE-2 deficiency that leads to decreased transport of vital dietary components, gut dysbiosis, proinflammatory gut status, increased permeability of the gut-blood barrier (GBB), and systemic inflammation. More clinical research is needed to substantiate further the linkages described above and evaluate the potential significance of gut microbiota as a diagnostic tool. Meanwhile, it is prudent to propose changes in dietary recommendations in favor of a high fiber diet or supplementation with SCFAs or probiotics to prevent or alleviate the neuropsychiatric ramifications of COVID-19.

Health effects of dietary sulfated polysaccharides from seafoods and their interaction with gut microbiota.

Various dietary sulfated polysaccharides (SPs) have been isolated from seafoods, including edible seaweeds and marine animals, and their health effects such as antiobesity and anti-inflammatory activities have attracted remarkable interest. Sulfate groups have been shown to play important roles in the bioactivities of these polysaccharides. Recent in vitro and in vivo studies have suggested that the biological effects of dietary SPs are associated with the modulation of the gut microbiota. Dietary SPs could regulate the gut microbiota structure and, accordingly, affect the production of bioactive microbial metabolites. Because of their differential chemical structures, dietary SPs may specifically affect the growth of certain gut microbiota and associated metabolite production, which may contribute to variable health effects. This review summarizes the latest findings on the types and structural characteristics of SPs, the effects of different processing techniques on the structural characteristics and health effects of SPs, and the current understanding of the role of gut microbiota in the health effects of SPs. These findings might help in better understanding the mechanism of the health effects of SPs and provide a scientific basis for their application as functional food.

Statistical Optimization of Parameters for Enhanced Bioactive Metabolites Produced by Streptomyces hygroscopicus AVS7

The modern technology focuses on developing a novel statistical approach for highest yield of bioactive microbial metabolites which contain therapeutic properties, eventually leading to a promising strategy for treating various diseases and disorders. In this research, we aimed to develop the optimization process for maximum yield of crude pigmented secondary metabolites (CPSM) from Streptomyces hygroscopicus AVS7 through statistical approaches and determine its antimicrobial activity. The isolate produced maximum of 2.92 g/L on 9th day in starch casein nitrate (SCN) medium, and employing the SCN medium as seed medium, the research has initiated one factor at a time (OFT) for screening the essential physical, physiological and biological parameters. The OFT-screened factors were further determined for their importance through Plackett–Burman (PB) design, and the PB results revealed the significant factors (sesame oil cake, KNO3, glycerol, glucose, casein and urea). The experimentation was carried to Box-Behnken (BB) design–RSM using significant factors for the evaluation of interaction between the factors influencing the highest yield of CPSM, and the model was validated. The maximum CPSM extract was yielded by culturing the S. hygroscopicus AVS7 in the optimized medium, and there was twofold increase in the yield of CPSM extract when compared to seed medium. This statistical approach is a low-cost and economical method to develop maximum CPSM for medicinal and industrial purposes. The produced CPSM was found to contain the antimicrobial properties. Further, the research leads to the in vitro and in vivo assessment of purified bioactive secondary metabolite.

Industrially Important Enzyme and Plant Growth Promoter Potential of Soil Actinomycetes

IJRASB is one of the best Journals publishing Research Paper for International Journal of Applied Science and Research,Scientific Research,Engineering Science,Technology and Research and Scientific Research.

Short-Chain Fatty Acids Improve Poststroke Recovery via Immunological Mechanisms.

Recovery after stroke is a multicellular process encompassing neurons, resident immune cells, and brain-invading cells. Stroke alters the gut microbiome, which in turn has considerable impact on stroke outcome. However, the mechanisms underlying gut-brain interaction and implications for long-term recovery are largely elusive. Here, we tested the hypothesis that short-chain fatty acids (SCFAs), key bioactive microbial metabolites, are the missing link along the gut-brain axis and might be able to modulate recovery after experimental stroke. SCFA supplementation in the drinking water of male mice significantly improved recovery of affected limb motor function. Using in vivo wide-field calcium imaging, we observed that SCFAs induced altered contralesional cortex connectivity. This was associated with SCFA-dependent changes in spine and synapse densities. RNA sequencing of the forebrain cortex indicated a potential involvement of microglial cells in contributing to the structural and functional remodeling. Further analyses confirmed a substantial impact of SCFAs on microglial activation, which depended on the recruitment of T cells to the infarcted brain. Our findings identified that microbiota-derived SCFAs modulate poststroke recovery via effects on systemic and brain resident immune cells.SIGNIFICANCE STATEMENT Previous studies have shown a bidirectional communication along the gut-brain axis after stroke. Stroke alters the gut microbiota composition, and in turn, microbiota dysbiosis has a substantial impact on stroke outcome by modulating the immune response. However, until now, the mediators derived from the gut microbiome affecting the gut-immune-brain axis and the molecular mechanisms involved in this process were unknown. Here, we demonstrate that short-chain fatty acids, fermentation products of the gut microbiome, are potent and proregenerative modulators of poststroke neuronal plasticity at various structural levels. We identified that this effect was mediated via circulating lymphocytes on microglial activation. These results identify short-chain fatty acids as a missing link along the gut-brain axis and as a potential therapeutic to improve recovery after stroke.

Immune recognition ofmicrobial metabolites.

Mucosal immunology research continues its fascination with microbial metabolites. In 2019, researchers uncovered extended functions for microbial metabolites in immunity, deepening our understanding of the regulation and function of metabolite-reactive immune cells, and revealed the receptors by which immune cells can recognize bioactive microbial metabolites. In the past year, researchers have gained a deeper understanding of the interactions between immune cells and microbially derived metabolites. Wendy Garrett describes the new insights into the receptors, immune cells and pathways triggered by microbial metabolites.

Awakening ancient polar Actinobacteria: diversity, evolution and specialized metabolite potential.

Polar and subpolar ecosystems are highly vulnerable to global climate change with consequences for biodiversity and community composition. Bacteria are directly impacted by future environmental change and it is therefore essential to have a better understanding of microbial communities in fluctuating ecosystems. Exploration of Polar environments, specifically sediments, represents an exciting opportunity to uncover bacterial and chemical diversity and link this to ecosystem and evolutionary parameters. In terms of specialized metabolite production, the bacterial order Actinomycetales, within the phylum Actinobacteria are unsurpassed, producing 10 000 specialized metabolites accounting for over 45 % of all bioactive microbial metabolites. A selective isolation approach focused on spore-forming Actinobacteria of 12 sediment cores from the Antarctic and sub-Arctic generated a culture collection of 50 strains. This consisted of 39 strains belonging to rare Actinomycetales genera including Microbacterium, Rhodococcus and Pseudonocardia. This study used a combination of nanopore sequencing and molecular networking to explore the community composition, culturable bacterial diversity, evolutionary relatedness and specialized metabolite potential of these strains. Metagenomic analyses using MinION sequencing was able to detect the phylum Actinobacteria across polar sediment cores at an average of 13 % of the total bacterial reads. The resulting molecular network consisted of 1652 parent ions and the lack of known metabolite identification supports the argument that Polar bacteria are likely to produce previously unreported chemistry.

A Forward Chemical Genetic Screen Reveals Gut Microbiota Metabolites That Modulate Host Physiology

The intestinal microbiota produces tens of thousands of metabolites. Here, we used host sensing of small molecules by G-protein coupled receptors (GPCRs) as a lens to illuminate bioactive microbial metabolites that impact host physiology. We screened 144 human gut bacteria against the non-olfactory GPCRome and identified dozens of bacteria that activated both well-characterized and orphan GPCRs, including strains that converted dietary histidine into histamine and shaped colonic motility; a prolific producer of the essential amino acid L-Phe, which we identified as an agonist for GPR56 and GPR97; and a species that converted L-Phe into the potent psychoactive trace amine phenethylamine, which crosses the blood-brain barrier and triggers lethal phenethylamine poisoning after monoamine oxidase inhibitor administration. These studies establish an orthogonal approach for parsing the microbiota metabolome and uncover multiple biologically relevant host-microbiota metabolome interactions.

Abstract 1265: Protective efficacy of gut microbiome and microbial metabolites after rice bran consumption against colon tumorigenesis

Abstract Colorectal cancer (CRC) is the 2nd leading cause of cancer-related deaths in US. Therefore, practical interventions that reduce incidence of adenomatous polyps and/or prevent their progression to CRC are urgently needed. In this regard, several studies have reported the chemopreventive potential of dietary rice bran [a wasted ‘by-product' of white rice (Oryza sativa) processing] against CRC. Given that high heat can stabilize rice-bran for safe human consumption, our research efforts are evaluating ‘stabilized-rice bran', as a functional food for CRC control and prevention. Rice bran has been previously shown to increase colonization of native gut probiotics and undergo microbiota fermentation. However, little is known about rice bran constituents as prebiotics, microbial substrates that promote healthy gut microbiota, and how these microbes produce novel, bioactive microbial metabolites. In this regard, our studies show that native gut probiotic - fermented rice bran extracts have strong in vitro activity against CRC cells and significantly decrease their colonosphere formation (a stem cell characteristic). Rice bran (fermented and non-fermented) also strongly inhibits TNF alpha-induced NF-kappa B activation and interleukin (IL)- 4-induced expression of CD44, which along with its variant form (CD44 v3-v6) plays an essential role in the adhesion and infiltration of inflammatory cells in CRC. Notably, even the stool extracts from rice bran-fed CRC survivors showed increased inhibitory effects on CRC cell viability compared to the stools collected from the same individuals prior to rice bran consumption. Next, extensive in vivo investigations were performed to determine the relative efficacy of dietary rice bran-modified gut microbiota and microbiota-fermented rice bran on inflammation associated-colon tumorigenesis. First, Bifidobacterium Longum -fermented (fermented with selected rice bran responsive microbe that was induced during rice bran feeding clinical trials) and non-fermented dietary rice bran were fed to conventionally-raised or germ-free mice and evaluated for their comparative efficacy against azoxymethane (AOM)/ dextran sodium sulphate (DSS)-induced CRC. In second set of studies, we ‘humanized' gut of germ-free mice with stool inoculum from rice bran feeding human clinical trials and evaluated their efficacy against AOM/DSS-induced CRC. In conventional mice study, both the rice bran diets showed protective efficacy against CRC. Interestingly, germ-free mice having undergone transfaunation with rice-bran modified stool inoculum showed significantly less cancerous lesions compared to mice humanized with control stool inoculums, indicating that rice bran has the potential to re-structure the ‘high risk' gut microflora of CRC patients towards the colonization of populations with protective effects against CRC growth and progression. Citation Format: Akhilendra K. Maurya, Sushil Kumar, Rama Kant, Dileep Kumar, Bupinder Raina, Anita Yadav, Elizabeth P. Ryan, Komal Raina. Protective efficacy of gut microbiome and microbial metabolites after rice bran consumption against colon tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1265.

Antimicrobial activities of culturable microorganisms (actinomycetes and fungi) isolated from Chaabe Cave, Algeria

The discovery of new antibiotics and other bioactive microbial metabolites is a priority given the frequency of the emerging multi-drug resistant pathogenic microorganisms. Thus, scientists are searching for new antibiotics in microorganisms isolated from extreme habitats such as caves. In the present study, we aimed to perform the first analysis on culturable microorganisms in the Chaabe Cave (Algeria), and to test the antimicrobial activities of the isolates (Streptomyces spp. and Penicillium spp.). The potential for antimicrobial activity of 47 strains of actinomycetes and 23 strains of fungi were tested on Candida albicans, Staphylococcus aureus, Micrococcus luteus, Listeria monocytogenes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. The identification of the most active actinomycetes strains by 16S rRNA gene sequence analysis revealed that these isolates were exclusively affiliated to the genus Streptomyces. On the other hand, the fungi were determined by phylogenetic analysis based on the ITS region or on the β tubulin gene and were affiliated to the genera Readeriella, Cladosporium, Aspergillus, Penicillium, Beauveria, Alternaria, Rhizopus, and Rhizomucor. The strains showed strong inhibitory activity against pathogenic microorganisms and the diameters of the inhibition zones vary between 7.5 and 34 mm for Streptomyces strains, and between 6.5 and 19.50 mm for Penicillium strains. The data indicated that the majority (72.86%) of the 70 isolates were active against at least one of the tested microorganisms. The production of nonpolyenic antifungal substances by active Streptomyces isolates was investigated using several criteria (antibacterial activity, ergosterol inhibition, and UV-visible spectra) of active extracts. The results were promising and showed that the metabolites produced by the actinomycete strains do not have a UV-visible spectrum characteristic of a polyenic structure. The Chaabe Cave possesses a diversity of microorganisms that could lead to new antibiotics necessary in the fight against drug-resistant pathogens and warrant further study.

Aneurinifactin, a new lipopeptide biosurfactant produced by a marine Aneurinibacillus aneurinilyticus SBP-11 isolated from Gulf of Mannar: Purification, characterization and its biological evaluation

Biosurfactants are microbial-derived amphiphilic molecules having hydrophobic and hydrophilic moieties produced by bacteria, fungi, yeasts and algae and are extracellular or cell wall-associated compounds. In an ongoing survey for bioactive microbial metabolites from microbes isolated from diverse ecological niches, a new lipopeptide biosurfactant was identified from a marine bacterium; Aneurinibacillus aneurinilyticus strain SBP-11, which was isolated from a marine diversity hotspot, Gulf of Mannar, India. A new lipopeptide biosurfactant was purified and characterized based on TLC, FT-IR, NMR, GC–MS, HPLC, MALDI-TOF-MS and tandem MS analysis as Stearic acid-Thr-Tyr-Val-Ser-Tyr-Thr (named as Aneurinifactin). The critical micelle concentration of Aneurinifactin was 26mgL−1 at a surface tension of 26mNm−1. Further, the biosurfactant showed stable emulsification at a wide range of pH (2–9) and temperature up to 80°C. Aneurinifactin showed promising antimicrobial activity and concentration dependent efficient oil recovery. This is the first report on Aneurinifactin, a lipopeptide biosurfactant produced by a marine A. aneurinilyticus SBP-11, which could be explored as a promising candidate for use in various biomedical and industrial applications.

Pontifactin, a new lipopeptide biosurfactant produced by a marine Pontibacter korlensis strain SBK-47: Purification, characterization and its biological evaluation

Abstract In an ongoing survey for bioactive microbial metabolites from different biospheres of India, a new marine bacterium identified as Pontibacter korlensis strain SBK-47 was isolated from the coastal waters of Karaikal, Puducherry, India, which produced a novel lipopeptide biosurfactant. The biosurfactant was purified and structurally elucidated as Palmitic acid-Ser-Asp-Val-Ser-Ser based on TLC, FT-IR, NMR, GC–MS, HPLC, MALDI-TOF and tandem MS analysis. This novel lipopeptide biosurfactant was named as Pontifactin. Pontifactin exhibited a surface tension reduction and critical micelle concentration (CMC) of 25 mN m−1 and 25 mg L−1, respectively. Furthermore, the biosurfactant showed emulsification and surface tension stability over a wide range of pH (4–10) and temperature up to 100 °C. Pontifactin showed promising antimicrobial activity against Streptococcus mutans, Micrococcus luteus, Salmonella typhi and Klebsiella oxytoca at a biosurfactant concentration ranging between 1 and 2 mg mL−1 and maximum anti-biofilm activity at the biosurfactant concentration of 2 mg mL−1 against Bacillus subtilis, Staphylococcus aureus, Salmonella typhi and Vibrio cholerae. This is the first report on Pontifactin, a multifunctional lipopeptide biosurfactant, produced by a marine Pontibacter korlensis strain SBK-47, exhibiting promising surface-active, antimicrobial and anti-biofilm activities and thus finds possible use in biomedical applications.

Antimicrobial activities of a promising glycolipid biosurfactant from a novel marine Staphylococcus saprophyticus SBPS 15.

Biosurfactants have gained a renewed interest in the recent years for their commercial application in diverse research areas. Recent evidences suggest that the antimicrobial activities exhibited by biosurfactants make them promising molecules for the application in the field of therapeutics. Marine microbes are well known for their unique metabolic and functional properties; however, few reports are available till date regarding their biosurfactant production and antimicrobial potential. In an ongoing survey for bioactive microbial metabolites from microbes isolated from diverse ecological niches, a marine Staphylococcus saprophyticus SBPS 15 isolated from the petroleum hydrocarbon contaminated coastal site, Puducherry, India, was identified as a promising biosurfactant producer based on multiple screening methods. This bacterium exhibited growth-dependent biosurfactant production and the recorded yield was 1.345 ± 0.056 g/L (on dry weight basis). The biosurfactant was purified and chemically characterized as a glycolipid with a molecular mass of 606.7 Da, based on TLC, biochemical estimation methods, FT-IR spectrum and MALDI-TOF–MS analysis. Further, the estimated molecular mass was different from the earlier reports on biosurfactants. This new glycolipid biosurfactant exhibited a board range of pH and temperature stability. Furthermore, it revealed a promising antimicrobial activity against many tested human pathogenic bacterial and fungal clinical isolates. Based on these observations, the isolated biosurfactant from the marine S. saprophyticus revealed board physicochemical stabilities and possess excellent antimicrobial activities which proves its significance for possible use in various therapeutic and biomedical applications. To the best of our knowledge, this is the first report of a biosurfactant from the bacterium, S. saprophyticus.