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Abstract: The present study was undertaken to determine the mechanism of antibacterial activity of a polyphenolic fraction, composed of mainly catechin and isorhamnetin, previously isolated from Kombucha, a 14‐day fermented beverage of sugared black tea, against the enteropathogen Vibrio cholerae N16961. Bacterial growth was found to be seriously impaired by the polyphenolic fraction in a dose‐dependent manner. Scanning Electron Microscopy demonstrated morphological alterations in bacterial cells when exposed to the polyphenolic fraction in a concentration‐dependent manner. Permeabilization assays confirmed that the fraction disrupted bacterial membrane integrity in both time‐ and dose‐dependent manners, which were proportional to the production of intracellular reactive oxygen species (ROS). Furthermore, each of the polyphenols catechin and isorhamnetin showed the ability to permeate bacterial cell membranes by generating oxidative stress, thereby suggesting their role in the antibacterial potential of Kombucha. Thus, the basic mechanism of antibacterial activity of the Kombucha polyphenolic fraction against V. cholerae involved bacterial membrane permeabilization and morphological changes, which might be due to the generation of intracellular ROS. To the best of our knowledge, this is the first report on the investigation of antibacterial mechanism of Kombucha, which is mostly attributed to its polyphenolic content. Significance and Impact of the Study: The emergence of multidrug‐resistant Vibrio cholerae strains has hindered an efficient anti‐Vibrio therapy. This study has demonstrated the membrane damage‐mediated antibacterial mechanism of Kombucha, a popular fermented beverage of sugared tea, which is mostly attributed to its polyphenolic content. This study also implies the exploitation of Kombucha as a potential new source of bioactive polyphenols against V. cholerae. [ABSTRACT FROM AUTHOR]

Flavobacterium rigense strain PR2, a broad-spectrum mercury-resistant bacterium abundantly present in soil exhibited multiple metal resistance properties. Mercury resistance was due to the sequential action of two mercury-detoxicating enzymes, organomercurial lyase and mercuric reductase. The levels of these enzyme activities were determined using different mercury compounds as inducers and substrates. Mercuric reductase was partially purified from the bacterium and the physicochemical properties of the enzyme were studied. The effect of several enzyme inhibitors and heavy metal ions on the enzyme activity was also studied. [ABSTRACT FROM AUTHOR]

Ionotropic glutamate receptors are ligand-gated nonselective cation channels that mediate neurotransmission in the central nervous system of animals. Plants possess homologous proteins called glutamate receptor-like channels (GLRs) which are involved in vital physiological processes including seed germination, long-distance signaling, chemotaxis, Ca 2+ signaling etc. Till now, a comprehensive genome-wide analysis of the GLR gene family members in different economically important species of Brassica is missing. Considering the origin of allotetraploid Brassica napus from the hybridization between the diploid Brassica oleracea and Brassica rapa, we have identified 11, 27 and 65 GLR genes in B. oleracea, B. rapa and B. napus, respectively showing an expansion of this gene family in B. napus. Chromosomal locations revealed several tandemly duplicated GLR genes in all the three species. Moreover, the gene family expanded in B. napus after allopolyploidization. The phylogenetic analysis showed that the 103 GLRs are classified into three main groups. The exon-intron structures of these genes are not very conserved and showed wide variation in intron numbers. However, protein sequences are much conserved as shown by the presence of ten short amino acid sequence motifs. Predicted cis-acting elements in 1 kb promoters of GLR genes are mainly involved in light, stress and hormone responses. RNA-seq analysis showed that in B. oleracea and B. rapa, some GLRs are more tissue specific than others. In B. napus, some GLRs are downregulated under cold stress, while others are upregulated. In summary, this bioinformatic study of the GLR gene family of the three Brassica species provides evidence for the expansion of this gene family in B. napus and also provided useful information for in-depth studies of their biological functions in Brassica., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

A histidine-based amphiphilic peptide ( P ) has been found to form an injectable transparent hydrogel in phosphate buffer solution over a pH range from 7.0 to 8.5 with an inherent antibacterial property. It also formed a hydrogel in water at pH = 6.7. The peptide self-assembles into a nanofibrillar network structure which is characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy, small-angle X-ray scattering, Fourier-transform infrared spectroscopy, and wide-angle powder X-ray diffraction. The hydrogel exhibits efficient antibacterial activity against both Gram-positive bacteria Staphylococcus aureus ( S. aureus ) and Gram-negative bacteria Escherichia coli ( E. coli ). The minimum inhibitory concentration of the hydrogel ranges from 20 to 100 μg/mL. The hydrogel is capable of encapsulation of the drugs naproxen (a non-steroidal anti-inflammatory drug), amoxicillin (an antibiotic), and doxorubicin, (an anticancer drug), but, selectively and sustainably, the gel releases naproxen, 84% being released in 84 h and amoxicillin was released more or less in same manner with that of the naproxen. The hydrogel is biocompatible with HEK 293T cells as well as NIH (mouse fibroblast cell line) cells and thus has potential as a potent antibacterial and drug releasing agent. Another remarkable feature of this hydrogel is its magnification property like a convex lens.

Background: Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer and the main cause of cancer death globally. The use of medicinal herbs as chemotherapeutic agents in cancer treatment is receiving attention as they possess no or minimum side effects. Isorhamnetin (IRN), a flavonoid, has been under attention for its anti-inflammatory and anti-proliferative properties in a number of cancers, including colorectal, skin, and lung cancers. However, the in vivo mechanism of isorhamnetin to suppress liver cancer has yet to be explored., Methods and Result: HCC was induced by N-diethylnitrosamine (DEN) and carbon tetrachloride (CCL 4 ) in Swiss albino mice. Isorhamnetin (100 mg/kg body weight) was given to examine its anti-tumor properties in HCC mice model. Histological analysis and liver function assays were performed to assess changes in liver anatomy. Probable molecular pathways were explored using immunoblot, qPCR, ELISA, and immunohistochemistry techniques. Isorhamnetin inhibited various pro-inflammatory cytokines to suppress cancer-inducing inflammation. Additionally, it regulated Akt and MAPKs to suppress Nrf2 signaling. Isorhamnetin activated PPAR-γ and autophagy while suppressing cell cycle progression in DEN + CCl 4 -administered mice. Additionally, isorhamnetin regulated various signaling pathways to suppress cell proliferation, metabolism, and epithelial-mesenchymal transition in HCC., Conclusion: Regulating diverse cellular signaling pathways makes isorhamnetin a better anti-cancer chemotherapeutic candidate in HCC. Importantly, the anti-TNF-α properties of isorhamnetin could prove it a valuable therapeutic agent in sorafenib-resistant HCC patients. Additionally, anti-TGF-β properties of isorhamnetin could be utilized to reduce the EMT-inducing side effects of doxorubicin., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Phototrophic biofilms collected from intertidal sediments of the world's largest tidal mangrove forest were cultured in two sets of a biofilm-promoting culture vessel having hydrophilic glass surface and hydrophobic polymethyl methacrylate surface wherein 16 priority polycyclic aromatic hydrocarbons (PAHs) were spiked. Biofilms from three locations of the forest were most active in sequestering 98-100% of the spiked pollutants. PAH challenge did not alter the biofilm phototrophic community composition; rather biofilm biomass production and synthesis of photosynthetic pigments and extracellular polymeric substances (EPS) were enhanced. Photosynthetic pigment and EPS synthesis were sensitive to vessel-surface property. The lowest mean residual amounts of PAHs in the liquid medium as well as inside the biofilm were recorded in the very biofilm cultivated in the hydrophobic flask where highest values of biofilm biomass, total chlorophyll, released polysaccharidic (RPS) carbohydrates, RPS uronic acids, capsular polysaccharidic (CPS) carbohydrates, CPS proteins, CPS uronic acids and EPS hydrophobicity were obtained. Ratios of released RPS proteins: polysaccharides increased during PAH sequestration whereas the ratios of CPS proteins: polysaccharides remained constant. Efficacious PAH removal by the overlying phototrophic biofilm will reduce the entry of these contaminants in the sediments underneath and this strategy could be a model for "monitored natural recovery"., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The distribution of polycyclic aromatic hydrocarbons (PAHs) in the surface water and sediments in five regions of the Indian Sundarbans was assessed. The capability of microbial biofilm communities to sequester PAHs in a biofilm-promoting vessel was evaluated. The total PAH concentration of water and sediments ranged from undetectable to 125 ng ml -1 and 4880 to 2 × 10 4  ng g -1 dry weight respectively. The total PAHs concentration of sediments exceeded the Effects Range-Low value and the recommended Effects Range-Median values, implying the PAHs might adversely affect the biota of the Sundarbans. Pyrogenic and petrogenic sources of PAH contamination were identified in most of the sampling sites. Indigenous biofilms were cultivated in a patented biofilm-promoting culture vessel containing liquid media spiked with 16 priority PAHs. Biofilm-mediated 97-100% removal efficiency of 16 PAHs was attained in all media. There was no significant difference between the mean residual PAH from the liquid media collected from hydrophobic and hydrophilic flasks. Residual amounts of acenaphthene (Ace), anthracene (Ant), benzo(b)fluoranthene [B(b)F], benzo(a)pyrene [B(a)P] and benzo(g,h,i)perylene [B(g,h,i)P] showed differences when cultivated in hydrophobic and hydrophilic flasks. The mean residual amounts of total PAHs extracted from biofilm biomasses were variable. A biofilm obtained from a specific sampling site cultured in the hydrophobic flask showed higher PAH sequestration when compared to the removal attained in the hydrophilic flask. Relative abundances of different microbial communities in PAH-sequestering biofilms revealed bacterial phyla including Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Chloroflexi and Planctomycetes as well as members of Ascomycota phylum of fungi. The dominance of Candida tropicalis, Clostridium butyricum, Sphingobacterium multivorum and Paecilomyces fulvus were established., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The ability of P. laurentii strain RY1 to remediate lead (Pb 2+ ) from water was investigated in batch and column studies. The lead removal ability of non-viable biomass, non-viable biomass immobilised on agar-agar (biobeads) and agar-agar at different pH was compared in batch studies. It was found that among the three, biobeads have maximum ability to remove Pb 2+ followed by biomass and agar-agar beads. Maximum and almost equal lead removal by biobeads was observed at both neutral and alkaline pH making it a novel and more applicable bioremediator as all other reported bioremediators have a single pH for optimum activity. Studies were performed to determine the optimum conditions for lead removal from aqueous solutions for biobeads. The physical and chemical characterization of the biobeads before and after Pb 2+ biosorption was done by using S.E.M. and F.T.I.R. respectively. The adsorption of Pb 2+ on biobeads obeyed the Langmuir adsorption isotherm and pseudo first order kinetics. These mean that the Pb 2+ binding sites are identical, located on the surface of the adsorbant and the rate of Pb 2+ removal from aqueous solution is directly proportional to the number of Pb 2+ binding sites on the biobeads. The thermodynamics of the biosorption process is also investigated. The binding capacity of the biobeads in batch study was found to be 52.91mg/gm which is higher in comparison to other reported yeast bioremediators. The used biobeads can be desorbed using 0.1(M) CaCl 2 . The desorbed biobeads can be used subsequently for several cycles of lead removal making it cost-effective. Column studies were also performed for biobeads with the help of Thomas model for examining its suitability for industrial application. Maximum specific lead uptake of the biobeads when applied in the column was found to be 58.26mg/gm which being promising makes it suitable for application in industries involved in the treatment of wastewater contaminated with high amounts of lead. The high mass transfer co-efficient indicate that small sized column can be used effectively to remove high amounts of lead which makes the bioremediation process by the biobeads more economical and advantageous for industrial application. Several factors like effectiveness of the biobeads in Pb 2+ removal at both neutral and alkaline pH, reusability, high mass transfer co-efficient, regenerability and high binding capacity makes it a novel versatile, cost-effective and high utility bioremediator., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The use of traditional foods and beverages or their bioactive compounds as anti-virulence agents is a new alternative method to overcome the increased global emergence of antimicrobial resistance in enteric pathogens. In the present study, we investigated the anti-virulence activity of a polyphenolic fraction previously isolated from Kombucha, a 14-day fermented beverage of sugared black tea, against Vibrio cholerae O1. The isolated fraction was mainly composed of the polyphenols catechin and isorhamnetin. The fraction, the individual polyphenols and the combination of the individual polyphenols significantly inhibited bacterial swarming motility and expression of flagellar regulatory genes motY and flaC, even at sub-inhibitory concentrations. The polyphenolic compounds also decreased bacterial protease secretion and mucin penetration in vitro. In vivo study revealed that the polyphenolic fraction significantly inhibited V. cholerae induced fluid accumulation in the rabbit ileal loop model and intestinal colonization in suckling mice model. Therefore, the anti-virulence activity of the Kombucha polyphenolic fraction involved inhibition of motility and protease secretion of V. cholerae, thus preventing bacterial penetration through the mucin layer as well as fluid accumulation and bacterial colonization in the intestinal epithelial cells. The overall results implied that Kombucha might be considered as a potential alternative source of anti-virulence polyphenols against V. cholerae. To the best of our knowledge, this is the first report on the anti-virulence activity of Kombucha, mostly attributed to its polyphenolic content., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Chitin deacetylase, an enzyme isolated from Cryptococcus laurentii RY1, catalyzes the hydrolysis of acetamido group of N-acetyl-D-glucosamine unit of chitin. The primary objective of this study was to characterize and comprehend the activation of chitin deacetylase by DMSO. The secondary structure of the protein was determined by circular dichroism(CD).The interaction of protein with DMSO was evaluated by CD and tryptophan fluorescence spectroscopy which revealed that DMSO had no effect on overall secondary structure, but induced change in the tertiary structure of the enzyme. The interaction of chitin deacetylase with chitin in DMSO system when investigated by molecular dynamics simulation revealed stronger chitin deacetylase-chitin interaction involving several amino acid residues. The enhanced activity of the enzyme in presence of DMSO along with the fact that its k cat is highest of all other reported chitin deacetylases makes it a superior candidate in the industrial sector involved in chitosan production from chitin., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Heavy metals such as lead, chromium, and metalloid like arsenic dominate the pinnacle in posing a threat to life. Being environment-friendly, elucidating the mechanism by which microorganisms detoxify such elements has always been an active field of research hitherto. In the present study, we have investigated the capability of nitrogen-deprived Papiliotrema laurentii strain RY1 toward enhanced tolerance and neutralizing toxic elements. There were biosorption and bioprecipitation of lead and chromium at the cell surfaces. Bioprecipitation mechanisms included the formation of lead phosphates and pyromorphites from lead, grimaldite from chromium. Transcripts such as metallothionein, aquaporins, and arsenical pump-driving ATPase have been surmised to be involved in the detoxification of elements. Furthermore, activation of antioxidant defense mechanisms for the cells for each of the elements should contribute towards yeast's propagation. The efficiency of removal of elements for live cells and immobilized cells were high for lead and chromium. To the best of our knowledge, this is the first report of such high tolerance of lead, arsenic, and chromium for any yeast. The yeast showed such varied response under dual stress due to nitrogen starvation and in the presence of respective elements. The yeast possesses promising potentials in nitrogen deprived and enriched environments to aid in bioremediation sectors., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Stress response due to the lack of essential nutrient(s) for an organism has been a focal point of several scientific investigations. The present study investigates the cellular adaptations behind the ability of Papiliotrema laurentii strain RY1 to perpetuate without added nitrogen and propagate robustly in growth- limiting amount of nitrogen. We executed phenotypic (using scanning electron microscopy, differential interference contrast microscopy and transmission electron microscopy), microbiological and computational analyses to show multiple responses of dimorphism, capsule formation and autophagy as a survival strategy by the yeast upon nitrogen starvation. The roles of phosphomannose isomerase, phosphomannomutase and several autophagy-related transcripts aiding in such a response have been discussed., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A protease of the primary pathogen (Pseudoalteromonas agarivorans NW4327) of the disease affecting the Great Barrier Reef sponge Rhopaloeides odorabile was purified. Zymography demonstrated calcium-dependent collagenase and gelatinase activity of the purified protein. This metalloprotease was identified by matrix assisted laser desorption ionization time-of-flight mass spectrophotometry as a 52,509 Da U32 collagenase. Predicted tertiary structure of U32 collagenase (by Phyre2 fold recognition server) demonstrated 13% identity with known hydrolases establishing novelty of the enzyme. Molecular docking conceived two interacting loops of the collagenase that bound with collagen triple helices and two calcium ions remained centered between the loops. According to ConSurf multiple sequence alignment, the residues of loop1 of the collagenase were mostly conserved while variations among residues of loop2 were comparatively higher than loop1. Asp262, Glu263 of loop1 and Thr363, Lys364, Gln365 of loop2 participated in the interaction with Ca 2+ and collagen. Root mean square deviation and root mean square fluctuation values signified higher stability of the collagen-Ca 2+ -collagenase complex and greater structural stability of the residues of the loops in the complex compared to apocollagenase. Observed properties of NW4327 U32 collagenase and its interaction with collagen were different from similar enzymes of thermophilic bacteria and terrestrial pathogens., (Copyright © 2018. Published by Elsevier B.V.)

Levansucrase is a secretary enzyme of Acetobacter nitrogenifigens strain RG1. The enzyme shows enhanced activity in the presence of Hg 2+ in spite of being inhibited by other heavy metal ion Cd 2+ . In this study the structural characterization of levansucrase in native state as well as in the presence of Hg 2+ and Cd 2+ by CD spectroscopy is done. The secondary structures of the native enzyme and the enzyme treated with Hg 2+ and Cd 2+ on comparison by their CD spectra revealed that their spectra showed no significant difference indicating that both Hg 2+ as well as Cd 2+ had no effect on the overall secondary structure of the protein. The respective CD spectra on analysis revealed that they have almost identical percentage of secondary structural elements. The interaction of levansucrase with Hg 2+ as well as Cd 2+ was studied further by tryptophan fluorescence spectroscopy which on analysis revealed static quenching indicating protein-heavy metal complex formation. A blue shift in the tryptophan fluorescence spectra of Hg 2+ treated protein indicated that the tryptophan residues have moved to a more hydrophobic environment in the protein away from aqueous phase. The mechanism of interaction of enzyme with mercury and cadmium was determined from their tryptophan fluorescence spectra., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The primary pathogen of the Great Barrier Reef sponge Rhopaloeides odorabile, recently identified as a novel strain (NW4327) of Pseudoalteromonas agarivorans, produced collagenase which degraded R. odorabile skeletal fibers. We now report the collagenase of P. agarivorans as a metalloprotease which required Ca 2+ and Zn 2+ as cofactors. The collagenase was a TonB dependent receptor (TBDR) having a carboxypeptidase regulatory like domain (CRLD) in the N-terminal along with an outer membrane (OM) channel superfamily domain. The genes for TBDR sub-components and collagenase formed one unified entity in the genome of P. agarivorans NW4327. This association of a collagenase with a TBDR distinguished it from all known functional collagenases till date and for the first time, established the enzymatic capability of TBDRs. Predicted TBDR model demonstrated only 15% identity with ferripyoverdin receptor and the CRLD displayed merely 24% identity with carboxypeptidase catalytic chain. Presence of signal peptide, lack of transmembrane helices, absence of N-terminal in the cytoplasmic side, extracellular localization and recovery from the culture supernatant implicated that the TBDR was secreted. Stronger binding of the collagenase with marine sponge type IV collagen than type I collagen, revealed through molecular docking, indicated higher specificity of the enzyme towards type IV collagen., (Copyright © 2017 Elsevier B.V. All rights reserved.)