In vitro antioxidant activities of an exopolysaccharide from a salt pan bacterium Halolactibacillus miurensis

Production optimization and antioxidant potential of exopolysaccharide produced by a moderately halophilic bacterium Virgibacillus dokdonensis VITP14

This study aimed to enhance the extracellular polymeric substances (EPS) production of Virgibacillus dokdonensis VITP14 and explore its antioxidant potential. EPS and biomass production by VITP14 strain were studied under different culture parameters and media compositions using one factor at a time method. Among different nutrient sources, glucose and peptone were identified as suitable carbon and nitrogen sources. Furthermore, the maximum EPS production was observed at 5% of inoculum size, 5 g/L of NaCl, and 96 h of fermentation. Response surface methodology was employed to augment EPS production and investigate the optimal levels of nutrient sources with their interaction. The strain was observed to produce actual maximum EPS of about 26.4 g/L for finalized optimum medium containing glucose 20 g/L, peptone 10 g/L, and NaCl 50 g/L while the predicted maximum EPS was 26.5 g/L. There was a nine fold increase in EPS production after optimization study. Additionally, EPS has exhibited significant scavenging, reducing, and chelating potential (>85%) at their higher concentration. This study imparts valuable insights into optimizing moderately halophilic bacterial EPS production and evaluating its natural antioxidant properties. According to findings, V. dokdonensis VITP14 was a promising isolate that will provide significant benefits to biopolymer producing industries.

Exopolysaccharide production by salt-tolerant bacteria: Recent advances, current challenges, and future prospects

Natural biopolymers derived from exopolysaccharides (EPSs) are considered eco-friendly and sustainable alternatives to available traditional synthetic counterparts. Salt-tolerant bacteria inhabiting harsh ecological niches have evolved a number of unique adaptation strategies allowing them to maintain cellular integrity and assuring their long-term survival; among these, producing EPSs can be adopted as an effective strategy to thrive under high-salt conditions. A great diversity of EPSs from salt-tolerant bacteria have attracted widespread attention recently. Because of factors such as their unique structural, physicochemical, and functional characteristics, EPSs are commercially valuable for the global market and their application potential in various sectors is promising. However, large-scale production and industrial development of these biopolymers are hindered by their low yields and high costs. Consequently, the research progress and future prospects of salt-tolerant bacterial EPSs must be systematically reviewed to further promote their application and commercialization. In this review, the structure and properties of EPSs produced by a variety of salt-tolerant bacterial strains isolated from different sources are summarized. Further, feasible strategies for solving production bottlenecks are discussed, which provides a scientific basis and direct reference for more scientific and rational EPS development.

Preparation of chemically and thermally modified water caltrop epicarp (Trapa natans L.) adsorbent for enhanced adsorption of Ni(II) from aqueous solution

The present study aims to prepare waste water caltrop (Trapanatans L.) epicarp (WCS)-based adsorbents such as raw WCS (WCS-Raw), citric acid-grafted WCS (WCS-CA), acrylamide-grafted WCS (WCS-AM), and calcined WCS (WCS-Si) for Ni(II) removal from aqueous solution in batch adsorption process. The physical and chemical properties of the prepared adsorbents were investigated by different characterization techniques such as scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, nitrogen adsorption-desorption analyses, and pH at the Point of Zero Charge (pHpzc) in order to assess the suitability and effectiveness of the adsorbents for the removal of Ni(II) by understanding their surface morphology, chemical composition, porosity, and surface charge properties. The experimental Ni(II) adsorption data followed both the Langmuir isotherm and the pseudo-second-order kinetic model suggesting the adsorption process on the prepared adsorbents is well-described by these models. The modified adsorbents WCS-CA, WCS-AM, and WCS-Si exhibited a maximum adsorption capacity of 52.08, 40.32, and 158.73 mg/g, respectively, while WCS-Raw had a capacity of 29.06 mg/g. The thermodynamic study revealed that the adsorption process was feasible, spontaneous, and endothermic. The desorption study demonstrated that the adsorbents could be reused for multiple cycles with minimal loss of activity. The present work evidenced the potential practical applicability and sustainability of the WCS-based adsorbents as promising adsorbents in treating and removing Ni(II) from wastewater.

Importance of microbial amphiphiles: interaction potential of biosurfactants, amyloids, and other exo-polymeric-substances

Microorganisms produce a diverse group of biomolecules having amphipathic nature (amphiphiles). Microbial amphiphiles, including amyloids, bio-surfactants, and other exo-polymeric substances, play a crucial role in various biological processes and have gained significant attention recently. Although diverse in biochemical composition, these amphiphiles have been reported for common microbial traits like biofilm formation and pathogenicity due to their ability to act as surface active agents with active interfacial properties essential for microbes to grow in various niches. This enables microbes to reduce surface tension, emulsification, dispersion, and attachment at the interface. In this report, the ecological importance and biotechnological usage of important amphiphiles have been discussed. The low molecular weight amphiphiles like biosurfactants, siderophores, and peptides showing helical and antimicrobial activities have been extensively reported for their ability to work as quorum-sensing mediators. While high molecular weight amphiphiles make up amyloid fibers, exopolysaccharides, liposomes, or magnetosomes have been shown to have a significant influence in deciding microbial physiology and survival. In this report, we have discussed the functional similarities and biochemical variations of several amphipathic biomolecules produced by microbes, and the present report shows these amphiphiles showing polyphyletic and ecophysiological groups of microorganisms and hence can `be replaced in biotechnological applications depending on the compatibility of the processes.

Biomass and enzymatic activities of marine bacteria in the presence of multiple metals

Marine environments are a repository for metals, and humans have enhanced this phenomenon over the years. Heavy metals are notoriously toxic due to their ability to biomagnify in the food chain and interact with cellular components. Nevertheless, some bacteria have physiological mechanisms that enable them to survive in impacted environments. This characteristic makes them important as biotechnological tools for environmental remediation. Thus, we isolated a bacterial consortium in Guanabara Bay (Brazil), a place with a long metal pollution history. To test the growth efficiency of this consortium in Cu-Zn-Pb-Ni-Cd medium, we measured the activity of key enzymes of microbial activity (esterases and dehydrogenase) under acidic (4.0) and neutral pH conditions, as well as the number of living cells, biopolymer production, and changes in microbial composition during metal exposure. Additionally, we calculated the predicted physiology based on microbial taxonomy. During the assay, a slight modification in bacterial composition was observed, with low abundance changes and little production of carbohydrates. Oceanobacillus chironomi, Halolactibacillus miurensis, and Alkaliphilus oremlandii were predominant in pH 7, despite O. chironomi and Tissierella creatinophila in pH 4, and T. creatinophila in Cu-Zn-Pb-Ni-Cd treatment. The metabolism represented by esterases and dehydrogenase enzymes suggested bacterial investment in esterases to capture nutrients and meet the energy demand in an environment with metal stress. Their metabolism potentially shifted to chemoheterotrophy and recycling nitrogenous compounds. Moreover, concomitantly, bacteria produced more lipids and proteins, suggesting extracellular polymeric substance production and growth in a metal-stressed environment. The isolated consortium showed promise for bioremediation of multimetal contamination and could be a valuable tool in future bioremediation programs.

Structural and Functional Characterization of Exopolysaccharide Produced by a Novel Isolate Bacillus sp. EPS003

An exopolysaccharide (EPS)-producing soil bacterium was isolated and characterized using 16S rRNA as Bacillus sp. EPS003. EPS was precipitated using ethanol and % composition of total carbohydrate, and protein was determined. Monosaccharide composition was identified using thin layer chromatography (TLC), and it was found to be a levan. Fourier transform infrared (FTIR) spectrum revealed the peaks for carboxyl, hydroxyl, and amide functional groups. ¹H nuclear magnetic resonance (NMR) spectrum further confirmed the presence of fructose monomer. Field emission scanning electron microscopic images (FE-SEM) revealed porous and amorphous characteristics of EPS which was further confirmed with broad peaks in X-ray diffraction (XRD) spectrum. Elemental composition was determined using energy-dispersive X-ray analysis (EDAX). Thermogravimetric analysis (TGA) of EPS resulted in a residual mass of 33.81% at 548 °C indicating high thermal stability. In addition, solubility index and water-holding capacity of EPS were found to be 56% and 264%, respectively, making EPS suitable for various applications. Further, antioxidant potential of EPS was studied using hydroxyl and DPPH radical scavenging assays. In vitro cytotoxicity assessment using L929 cells and SK-MEL-3 cell lines clearly indicated that the EPS produced by the novel isolate Bacillus sp. EPS003 could serve as a potential anticancer agent.

Bacterial Exopolysaccharides as Emerging Bioactive Macromolecules: From Fundamentals to Applications

Microbial exopolysaccharides (EPS) are extracellular carbohydrate polymers forming capsules or slimy coating around the cells. EPS can be secreted by various bacterial genera that can help bacterial cells in attachment, environmental adaptation, stress tolerance and are an integral part of microbial biofilms. Several gut commensals (e.g., Lactobacillus, Bifidobacterium) produce EPS that possess diverse bioactivities. Bacterial EPS also has extensive commercial applications in the pharmaceutical and food industries. Owing to the structural and functional diversity, genetic and metabolic engineering strategies are currently employed to increase EPS production. Therefore, the current review provides a comprehensive overview of the fundamentals of bacterial exopolysaccharides, including their classification, source, biosynthetic pathways, and functions in the microbial community. The review also provides an overview of the diverse bioactivities of microbial EPS, including immunomodulatory, anti-diabetic, anti-obesity, and anti-cancer properties. Since several gut microbes are EPS producers and gut microbiota helps maintain a functional gut barrier, emphasis has been given to the intestinal-level bioactivities of the gut microbial EPS. Collectively, the review provides a comprehensive overview of microbial bioactive exopolysaccharides.

Bacillales: From Taxonomy to Biotechnological and Industrial Perspectives

For a long time, the genus Bacillus has been known and considered among the most applicable genera in several fields. Recent taxonomical developments resulted in the identification of more species in Bacillus-related genera, particularly in the order Bacillales (earlier heterotypic synonym: Caryophanales), with potential application for biotechnological and industrial purposes such as biofuels, bioactive agents, biopolymers, and enzymes. Therefore, a thorough understanding of the taxonomy, growth requirements and physiology, genomics, and metabolic pathways in the highly diverse bacterial order, Bacillales, will facilitate a more robust designing and sustainable production of strain lines relevant to a circular economy. This paper is focused principally on less-known genera and their potential in the order Bacillales for promising applications in the industry and addresses the taxonomical complexities of this order. Moreover, it emphasizes the biotechnological usage of some engineered strains of the order Bacillales. The elucidation of novel taxa, their metabolic pathways, and growth conditions would make it possible to drive industrial processes toward an upgraded functionality based on the microbial nature.

Bacterial polysaccharides-A big source for prebiotics and therapeutics

Bacterial polysaccharides are unique due to their higher purity, hydrophilic nature, and a finer three-dimensional fibrous structure. Primarily, these polymers provide protection, support, and energy to the microorganism, however, more recently several auxiliary properties of these biopolymers have been unmasked. Microbial polysaccharides have shown therapeutic abilities against various illnesses, augmented the healing abilities of the herbal and Western medicines, improved overall health of the host, and have exerted positive impact on the growth of gut dwelling beneficial bacteria. Specifically, the review is discussing the mechanism through which bacterial polysaccharides exert anti-inflammatory, antioxidant, anti-cancer, and anti-microbial properties. In addition, they are holding promising application in the 3D printing. The review is also discussing a perspective about the metagenome-based screening of polysaccharides, their integration with other cutting-edge tools, and synthetic microbiome base intervention of polysaccharides as a strategy for prebiotic intervention. This review has collected interesting information about the bacterial polysaccharides from Google Scholar, PubMed, Scopus, and Web of Science databases. Up to our knowledge, this is the first of its kind review article that is summarizing therapeutic, prebiotics, and commercial application of bacterial polysaccharides.

Characterization and protective effect against ultraviolet radiation of a novel exopolysaccharide from Bacillus marcorestinctum QDR3-1

Although exopolysaccharide (EPS) has been applied to various fields, EPS for UVR-mediated oxidative stress repair still needs further exploration. In this study, a novel EPS was isolated from the fermentation medium of Bacillus sp. QDR3-1 and its yield was 4.8 g/L (pH 8.0, 12 % glucose, 30 °C and 6 % NaCl). The pure fraction (named EPS-M1) was purified by DEAE-cellulose and Sephadex G-100 column. EPS-M1 was a heteropolysaccharide composed of Man, Glc, Gal, and Fuc with a molecular weight of 33.8 kDa. Scanning electron microscopy (SEM) observed a rough surface and reticular structure of EPS-M1, and EPS-M1 formed spherical aggregates in aqueous solution observed in atomic force microscopy (AFM). Thermal analysis revealed that the degradation temperature of EPS-M1 was 306 °C. Moreover, methylation and NMR analysis determined that EPS-M1 was consisted of →3)-Manp-(1→, →2,6)-Manp-(1→, →4,6)-Glcp-(1→, →3)-Glcp-(1→, →4)-Galp-(1→, →4)-Fucp-(1→, and T-Manp-(1→. Furthermore, the cytotoxicity and the repair ability of UVR-mediated cell damage of EPS-M1 were studied with L929 cells. The results showed that EPS-M1 had good biocompatibility and it could mitigate UVR-mediated cell damage by regulating the levels of cellular reactive oxygen species (ROS), depolarization of mitochondrial membrane potential (MMP) and Caspase-3/7 activity. Overall, the structure analysis and the protective effects of EPS against L929 cells exposed to UVR provided an experimental basis for EPS in practical applications.

Exopolysaccharides from Marine Microbes: Source, Structure and Application

The unique living environment of marine microorganisms endows them with the potential to produce novel chemical compounds with various biological activities. Among them, the exopolysaccharides produced by marine microbes are an important factor for them to survive in these extreme environments. Up to now, exopolysaccharides from marine microbes, especially from extremophiles, have attracted more and more attention due to their structural complexity, biodegradability, biological activities, and biocompatibility. With the development of culture and separation methods, an increasing number of novel exopolysaccharides are being found and investigated. Here, the source, structure and biological activities of exopolysaccharides, as well as their potential applications in environmental restoration fields of the last decade are summarized, indicating the commercial potential of these versatile EPS in different areas, such as food, cosmetic, and biomedical industries, and also in environmental remediation.

The response surface optimization of exopolysaccharide produced by Saccharomyces cerevisiae Y3 and its partial characterization

Response surface methodology (RSM) was used to optimize the conditions of exopolysaccharides (EPSs) by Saccharomyces cerevisiae Y3. The results indicated that the yield of EPS reached 4.52 ± 0.14 g/L with 10.30% (w/v) sucrose, 0.64% (w/v) yeast extract, liquid volume 141.5 mL, which was 2.40 times the original EPS yield. Y3 EPS contained 83.65 ± 0.16% of total sugars, 15.27 ± 0.26% of uronic acid, 0.78 ± 0.02% of protein and 0.30 ± 0.12% of sulfuric acid groups. Y3 EPS maintained a relatively low viscosity, with intrinsic viscosities of 306.58 mL/g (25 °C) and 200.91 mL/g (35 °C), respectively. The EPS had high water solubility index (WSI), high water holding capacity (WHC) and good emulsifying ability (EA). Meanwhile, the EPS could absorb metal ions such as Cu²⁺, Fe²⁺ and Zn²⁺. In addition, Y3 EPS exhibited good antioxidant properties and coagulated skim milk with a concentration-dependent manner. These results indicated that S. cerevisiae Y3 EPS had applicable prospects in medicine, food, especially the dairy industry.

Production, Characterization, and Antioxidant Activities of an Exopolysaccharide Extracted from Spent Media Wastewater after Leuconostoc mesenteroides WiKim32 Fermentation

Bacterial exopolysaccharides (EPSs) are important alternatives to plant polysaccharides in fermented products and exhibit antioxidant activity, which is particularly desirable for functional foods. This study evaluated the use of spent media wastewater (SMW) derived from kimchi fermentation for the production of an EPS and analyzed the characterization and antioxidant activity of the resulting EPS. The EPS concentration and conversion yields of sequential purification were 7.7-9.0 g/L and 38.6-45.1%, respectively. Fourier transform infrared spectra and NMR spectra indicated that the EPS was a linear glucan with α-(1 → 6) linkages. The EPS also exhibited thermal tolerance to high temperatures. In vitro antioxidant activity analyses indicated the scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, thiobarbituric acid reactance (TBAR), and ferric ion reducing antioxidant power (FRAP) values of 71.6-79.1, 28.2-33.0%, and 0.04-0.05 mM FeCl3, respectively. These results reveal that the EPS extracted from SMW has potential as a thermally tolerant, nontoxic, and natural antioxidant for industrial applications.

A review of extracellular polysaccharides from extreme niches: An emerging natural source for the biotechnology. From the adverse to diverse!

Every year, new organisms that survive and colonize adverse environments are discovered and isolated. Those organisms, called extremophiles, are distributed throughout the world, both in aquatic and terrestrial environments, such as sulfurous marsh waters, hydrothermal springs, deep waters, volcanos, terrestrial hot springs, marine saltern, salt lakes, among others. According to the ecosystem inhabiting, extremophiles are categorized as thermophiles, psychrophiles, halophiles, acidophiles, alkalophilic, piezophiles, saccharophiles, metallophiles and polyextremophiles. They have developed chemical adaptation strategies that allow them to maintain their cellular integrity, altering physiology or improving repair capabilities; one of them is the biosynthesis of extracellular polysaccharides (EPS), which constitute a slime and hydrated matrix that keep the cells embedded, protecting from environmental stress (desiccation, salinity, temperature, radiation). EPS have gained interest; they are explored by their unique properties such as structural complexity, biodegradability, biological activities, and biocompatibility. Here, we present a review concerning the biosynthesis, characterization, and potential EPS applications produced by extremophile microorganisms, namely, thermophiles, halophiles, and psychrophiles. A bibliometric analysis was conducted, considering research articles published within the last two decades. Besides, an overview of the culture conditions used for extremophiles, the main properties and multiple potential applications of their EPS is also presented.

Structural characterization, functional and biological activities of an exopolysaccharide produced by probiotic Bacillus licheniformis AG-06 from Indian polyherbal fermented traditional medicine

An exopolysaccharide (EPS) was purified from the probiotic bacterium Bacillus licheniformis AG-06 isolated from the polyherbal fermented traditional medicine (Ashwagandharishta) of Indian Ayurveda. High-performance liquid chromatography (HPLC) based compositional analysis exhibits the heteropolymeric nature of the EPS consisting of galactose, rhamnose, xylose, mannose, and glucose, as the monomeric units. Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic analyses confirm the presence of typical carbohydrate polymer functional groups and structural units, respectively. The purified EPS demonstrates the web-like fibrous and porous nature in scanning electron microscopic and atomic force microscopic studies. The purified EPS had shown 71.83% and 67.79% of flocculation and emulsification activities, respectively. Antioxidant activity was evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), nitric oxide, and superoxide free radicals and the scavenging actions were increased in a dose-dependent manner. Moreover, the purified EPS exhibits a significant cytotoxic activity against the human lung carcinoma cells (A549), which strongly suggests the anticancer potential of the EPS derived from B. licheniformis AG-06.

Structure and biological properties of exopolysaccharide isolated from Citrobacter freundii

This study aimed to investigate the molecular characterization, antioxidant activity in vitro, cytotoxicity study of an exopolysaccharide isolated from Citrobacter freundii. Firstly, the culture conditions were standardized by the Design of experiments (DoE) based approach, and the final yield of thecrude exopolysaccharide was optimized at 2568 ± 169 mg L^-1. One large fraction of exopolysaccharide was obtained from the culture filtrate by size exclusion chromatography and molecular characteristics were studied. A new mannose rich exopolysaccharide (Fraction-I) with average molecular weight ~ 1.34 × 10⁵ Da was isolated. The sugar analysis showed the presence of mannose and glucose in a molar ratio of nearly 7:2 respectively. The structure of the repeating unit in the exopolysaccharide was determined through chemical and 1D/2D- NMR experiments as: Finally, the antioxidant activity, and the cytotoxicity of the exopolysaccharide were investigated and the relationship with molecular properties was discussed as well.

Hetero-exopolysaccharide from the extremely halophilic Halomonas smyrnensis K2: production, characterization and functional properties in vitro

In this study, we firstly reported the production and the structural characterization of a novel hetero-exopolysaccharide namely EPS-K2 from the extremely halophilc Halomonas smyrnensis K2. Results revealed that EPS-K2 was mainly composed of three monosaccharides including mannose (66.69%), glucose (19.54%) and galactose (13.77%). EPS-K2 showed high thermostability with a degradation temperature around 260 °C, which could make it a suitable candidate for application in thermal processes. Moreover, EPS-K2 showed attractive functional properties. In fact, it exhibited potent antioxidant activity in a dose-dependent manner as assessed in analyses of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, iron chelating and DNA protection ability. Furthermore, EPS-K2 showed strong adhesion inhibition activity against Enterococcus faecalis (75.52 ± 3.35%) and Escherichia coli (61.95 ± 2.48%) at 1 g/l concentration, as well as a high biofilm disruption activity especially against E. coli (70.73 ± 2.78%), at 2 g/l concentration. According to its biotechnological properties, EPS-K2 could be exploited as functional ingredient in food, biomedicine, and pharmaceutical industries.

Structural characterization and functional properties of novel exopolysaccharide from the extremely halotolerant Halomonas elongata S6

Production of extracellular polysaccharides by halophilic Archaea and Bacteria has been widely reported and the members of the genus Halomonas have been identified as the most potential producers. In the present work, a novel exopolysaccharide (EPS-S6) produced by the extremely halotolerant newly isolated Halomonas elongata strain S6, was characterized. According to the HPAE-PAD results, EPS-S6 was mainly composed of glucosamine, mannose, rhamnose and glucose (1:0.9:0.7:0.3). EPS-S6 was highly negatively charged and its molecular weight was about 270 kDa. Studies on its functional properties showed that EPS-S6 had several potential features. It has noticeable antioxidant activities on 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) inhibition and DNA protection, good ability to inhibit and to disrupt pathogenic biofilms, excellent flocculation of kaolin suspension and interesting emulsifying properties at acidic, neutral and basic pH. Therefore, EPS-S6 could have potential biotechnological concern in several fields such as in food, cosmetic and environmental industries.

The Antioxidant Activity of Polysaccharides Derived from Marine Organisms: An Overview

Marine-derived antioxidant polysaccharides have aroused extensive attention because of their potential nutritional and therapeutic benefits. However, the comprehensive comparison of identified marine-derived antioxidant polysaccharides is still inaccessible, which would facilitate the discovery of more efficient antioxidants from marine organisms. Thus, this review summarizes the sources, chemical composition, structural characteristics, and antioxidant capacity of marine antioxidant polysaccharides, as well as their protective in vivo effects mediated by antioxidative stress reported in the last few years (2013-2019), and especially highlights the dominant role of marine algae as antioxidant polysaccharide source. In addition, the relationships between the chemical composition and structural characteristics of marine antioxidant polysaccharides with their antioxidant capacity were also discussed. The antioxidant activity was found to be determined by multiple factors, including molecular weight, monosaccharide composition, sulfate position and its degree.

Apoptotic role of marine sponge symbiont Bacillus subtilis NMK17 through the activation of caspase-3 in human breast cancer cell line

The aim of the present study was to evaluate the diverse potential biological activity of partially purified crude extract (PPCEBS) of marine Bacillus subtilis NMK17 associated with marine sponge Clathria frondifera. Symbionts were isolated from a marine sponge, only the potential strain which exhibited apoptosis was sequenced using 16S rRNA and extract of the active strain was subjected to purification using HPLC. The potential pro-apoptotic role of PPCEBS was investigated in MCF-7 human breast cancer cell line for cytotoxicity by MTT assay, which showed dose-dependent cytotoxicity on 24 h of exposure. The apoptotic findings demonstrated that PPCEBS significantly induces apoptosis, which was characterised by apoptotic morphological changes. Further, an increased expression of the Caspase 3 and Bax whereas decreased Bcl-2 was confirmed by immunofluorescence and western blotting analysis in MCF-7 cell line, which revealed that PPCEBS has potent apoptosis-inducing property. Added to the desirable apoptotic activity, PPCEBS exhibited excellent antibacterial and antioxidant activities too. The pharmacological effect of the marine sponge-associated bacteria from Gulf of Mannar India needs further attention in discovering new bioactive compounds. Our results suggested that the compounds present in the PPCEBS in marine bacterial B. subtilis NMK17 could be candidates for developing an apoptosis-specific drug with minimal toxicity. This study indicated that marine sponge-associated bacteria could be a good source to find the cytotoxic metabolites which would induce apoptosis and cause cancer cell death. Also, this study explores that marine natural products as a potential source of pharmaceuticals.

Exopolysaccharide from Pantoea sp. BCCS 001 GH isolated from nectarine fruit: production in submerged culture and preliminary physicochemical characterizations

Exopolysaccharide (EPS), as potential microbial base polysaccharide source, has plenty of applications due to its unique physicochemical structure. A Pantoea sp. BCCS 001 GH bacterium with the ability to produce a high amount of EPS was identified by 16S rRNA gene sequencing and biochemical tests. The synthesis of EPS by Pantoea sp. BCCS 001 GH was 13.50 g/L in 48 h when sucrose was used as substrate. The proposed protocol was desirably rapid for massive prodcution of EPS and showed the remarkable impact of sucrose and disodium hydrogen phosphate, peptone, Triton x-100 and 2% (v/v) inoculum size on the yields of EPS production. The EPS was mainly composed of glucose and galactose in a relative molar ration (glucose/galactose) of 85.18:14.82, respectively. The preliminary characterization showed the average molecular-weight of EPS is about 2.522 × 10⁶ Da. The microscopics morphology of polymer was formed irregularly shaped structures.

A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810

Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu²⁺, Ni²⁺, and Cr⁶⁺ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS for heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu²⁺ and Ni²⁺ were 140.8 ± 8.2 mg/g and 226.3 ± 3.3 mg/g at pH 5.0; however, for Cr⁶⁺ it was 215.2 ± 5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni²⁺ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.

Antioxidant status and gut microbiota change in an aging mouse model as influenced by exopolysaccharide produced by Lactobacillus plantarum YW11 isolated from Tibetan kefir

This study investigated the effect of exopolysaccharide (EPS) produced by Lactobacillus plantarum YW11 on the oxidative status and gut microbiota in an aging mouse model induced with d-galactose. The in vitro assay of the antioxidant activity of the EPS showed concentration-dependent (0.25-3.0 mg/mL) activities. At 3.0 mg/mL, the EPS reached the highest scavenging activities with half maximal inhibitory concentration values against hydroxyl radicals at 75.10% and 1.22 mg/mL, superoxide anion at 62.71% and 1.54 mg/mL, 2, 2-diphenyl-1-picrylhydrazyl at 35.11% and 0.63 mg/mL, and the maximal chelating rate on ferrous ion and the half-maximal chelating concentration of the EPS at 41.09% and 1.07 mg/mL, respectively. High doses of EPS (50 mg/kg per day) effectively relieved the oxidative stress in the aging mice with increased levels of glutathione peroxidase, superoxide dismutase, catalase, and total antioxidant capacity in mice serum by 21.55, 33.14, 61.09, and 38.18%, respectively, and decreased malondialdehyde level from 11.69 to 5.89 mmol/mL compared with those in the untreated aging mice model. The analysis of pyrosequencing sequence data from the gut microbiota revealed that the EPS could recover the microbiota diversity and phylotypes decreased or eliminated by the d-galactose treatment. The EPS could selectively decrease the abundance of Flexispira (37.5 fold), and increase the abundance of Blautia (36.5 fold) and Butyricicoccus (9.5 fold), which correspondingly decreased the content of nitrogen oxides to 9.87% and increased the content of short-chain fatty acids by 2.23 fold, thereby improving the oxidative and health conditions of the host intestinal tract. Further correlation analysis of core-microbiota variation induced by different treatments showed a strong correlation with oxidative phenotypes [catalase, goodness of prediction (Q²) = 0.49; total antioxidant capacity, Q² = 0.45; nitrogen oxides, Q² = 0.67; short-chain fatty acids, Q² = 0.55]. The fermented milk with L. plantarum YW11 containing EPS also showed favorable antioxidant and gut microbiota regulating activities. The present finding provided new insights into the functional mechanism of probiotics bioactivity.