Ecological restoration at pilot-scale employing site-specific rationales for small-patch degraded mangroves in Indian Sundarbans.

To date, degraded mangrove ecosystem restoration accomplished worldwide primarily aligns towards rehabilitation with monotypic plantations, while ecological restoration principles are rarely followed in these interventions. However, researchers admit that most of these initiatives' success rate is not appreciable often. An integrative framework of ecological restoration for degraded mangroves where site-specific observations could be scientifically rationalized, with co-located reference pristine mangroves as the target ecosystem to achieve is currently distinctively lacking. Through this experimental scale study, we studied the suitability of site-specific strategies to ecologically restore degraded mangrove patches vis-à-vis the conventional mono-species plantations in a highly vulnerable mangrove ecosystem in Indian Sundarbans. This comprehensive restoration framework was trialed in small discrete degraded mangrove patches spanning ~ 65 ha. Site-specific key restoration components applied are statistically validated through RDA analyses and Bayesian t-tests. 25 quantifiable metrics evaluate the restoration success of a ~ 3 ha degraded mangrove patch with Ridgeline distribution, Kolmogorov-Smirnov (K-S) tests, and Mahalanobis Distance (D2) measure to prove the site's near-equivalence to pristine reference in multiple ecosystem attributes. This restoration intervention irrevocably establishes the greater potential of this framework in the recovery of ecosystem functions and self-sustenance compared to that of predominant monoculture practices for vulnerable mangroves.

Surface Charge-Switchable Antifouling Block Copolymer with Bacteriostatic Properties.

Zwitterionic polymers are an emerging family of effective, low-fouling materials that can withstand unintended interactions with biological systems while exhibiting enhanced activity in bacterial matrix deterioration and biofilm eradication. Herein, we modularly synthesized an amphiphilic block copolymer, ZABCP, featuring potential bacteriostatic properties composed of a charge-switchable polyzwitterionic segment and a redox-sensitive pendant disulfide-labeled polymethacrylate block. The leucine-appended polyzwitterionic segment with alternatively positioned cationic amine and anionic carboxylate functionalities undergoes charge alterations (+ve → 0 → -ve) on pH variation. By introducing appropriate amphiphilicity, ZABCP forms distinct vesicles with redox-sensitive bilayer membranes and zwitterionic shielding coronas, enabling switching of surface charge. ZABCP vesicles exhibit 180 ± 20 nm hydrodynamic diameter, and its charge switching behavior in response to pH was confirmed by the change of zeta potential value from -23 to +36 mV. The binding interaction between ZABCP vesicles with lysozyme and pepsin proteins strengthens when the surface charge shifts from neutral (pH 7.4) to either anionic or cationic. This surface-charge-switchable phenomenon paves the way for implementing cationic ZABCP vesicles for bacterial cell growth inhibition, which is shown by the pronounced transition of cellular morphology, including clustering, aggregation, or elongation as well as membrane disruption for both Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative). Such enhanced bacteriostatic activity could be ascribed to a strong electrostatic interaction between cationic vesicles and negatively charged bacterial membranes, leading to cell membrane disruption. Overall, this study provides a tailor-made approach to adopt low-fouling properties and potential bacteriostatic activity using zwitterionic polymers through precise control of pH.

Dataset of biological community structure in Deepor Beel using eDNA approach-A RAMSAR wetland of Assam, India.

Deepor Beel, located in the state of Assam in India, is a Wetland of International Importance with a Wildlife Sanctuary and is the only RAMSAR site in the state. Though of invaluable ecological significance, the wetland is facing anthropogenic stressors, leading to rapid degradation of ecological health. In December 2022, surface water was collected from six stations of Deepor Beel to elucidate biological communities using the eDNA approach. At the time of sampling, in-situ environmental parameters were measured in triplicates. The dissolved nutrients and concentrations of metals and metalloids were estimated using UV-Vis Spectrophotometry and ICP-MS approaches respectively. The study revealed a high concentration of dissolved nitrate in the surface water. High-throughput sequencing using Nanopore sequencing chemistry in a MinION platform indicated the overwhelming abundance of Moraxellaceae (Prokaryotes) and Eumetazoa (Eukaryotes). The abundance of Cyprinidae were also encountered in the studied wetland reflecting the biodiversity of fish populations. High nitrate along with elucidated microbial signals are crucial to designate ecological health status of Deeper Beel. This study is aimed at generating baseline information to aid long-term monitoring and restoration of the Deepor Beel as well as the first comprehensive assessment of a RAMSAR Site located in northeast of India.

Exploring the influences of geographical variation on sequence signatures in the human gut microbiome.

Geography shapes the structure and function of human gut microbiomes. In this study, we have explored the available human gut microbiome 16S rRNA sequence datasets of cohorts representing large geographical gradients. The 16S rRNA sequences representing V3-V4 as well as V4 regions generated using Illumina sequencing chemistry in the MiSeq platform encompassing the United States of America, Chile, South Africa, Kuwait, and Malaysia were subjected to in-depth computational biology analyses. Firmicutes and Bacteroidetes were the most dominant phyla present in all studied cohorts but Actinobacteria was exclusively present in high abundance in cohorts from Malaysia (15.99%). The relative abundance of five families, namely Bacteroidaceae, Ruminococcaceae, Prevotellaceae, Clostridiaceae, and Eubacteriaceae were highest representing the studied cohorts. The permutational multivariate analysis of variance (PERMANOVA) showed that the dissimilarity in the gut microbiome structure of cohorts representing studied countries was significant (R2 = 0.28, P<0.001). The calculated Firmicutes to Bacteroidetes (F : B) ratio was found to be lowest in cohorts from South Africa (1.11) and Chile (0.95). The cohorts from South Africa exhibited the highest alpha diversity based on Hill numbers at q=0, whereas at q=1 and 2, cohorts from Malaysia had the highest alpha diversity. The beta diversity analysis revealed that cohorts from Chile formed a distinct cluster among all the studied geographical locations. For the first time, the study also showed that cohorts from Malaysia representing short geographical distances exhibited distinct intrapopulation differences in the gut microbiome and may not be influenced by cultural and genetic factors.

Seasonal variability of modern benthic foraminifera assemblages in a mangrove ecosystem from northeast coastal Bay of Bengal.

Benthic foraminifera assemblages, nutrient dynamics of surface and porewater from 10 intertidal sites spanning over two years (2019-2020) covering two major estuaries in Sundarbans mangrove were evaluated to understand role of seasonal precipitation and primary production (driven by eddy nutrients) with a focus on standing crop. Benthic foraminifera abundance ranged between 280 individuals/10 cc in pre-monsoon (2019), 415 individuals/10 cc in post-monsoon 2019 and 630 individuals/10 cc in post-monsoon (2020). Standing crop was highest in post-monsoon coinciding with eddy nutrients driven stoichiometry and increase in abundance of large diatom cells. Calcareous and agglutinated foraminifer taxa Ammonia sp.1, Quinqueloculina seminulum, Entzia macrescens and Textularia sp. respectively were frequent. Entzia macrescens was found in dense mangrove vegetation sites; exhibited strong relationship with sediment texture and pore water total organic carbon. One of the major findings is mangroves with pneumatophores improves oxygen availability in sediment and leads to an increase in standing crop.

First record of an Anthropocene marker plastiglomerate in Andaman Island, India.

One of the most significant environmental issues confronting our world is plastic trash, which is of particular concern to the marine environment. The sedimentary record of the planet may likely one day contain a horizon of plastic that can be potentially identified as an Anthropocene marker. Here we report the presence of 'plastiglomerate' from coastal habitats located in the Aves Island, Andaman Sea, India. This novel form of plastic pollution forms with the incineration of plastic litter in the environment and then mixing of organic/inorganic composite materials in the molten plastic matrix. The plastic pollutants were collected from the Aves Island beach during marine litter surveys. Micro-Raman (µ-Raman) spectroscopy was used to evaluate and confirm all putative plastic forms. Plastiglomerates were made of a polyethylene (PE) and polyvinyl chloride (PVC) matrix with inclusions of rock and sand. Therefore, our research offers new insight into the intricate process of plastiglomerates formation.

Hypervirulent Klebsiella pneumoniae Causing Neonatal Bloodstream Infections: Emergence of NDM-1-Producing Hypervirulent ST11-K2 and ST15-K54 Strains Possessing pLVPK-Associated Markers.

Klebsiella pneumoniae is a major cause of neonatal sepsis. Hypervirulent Klebsiella pneumoniae (hvKP) that cause invasive infections and/or carbapenem-resistant hvKP (CR-hvKP) limit therapeutic options. Such strains causing neonatal sepsis have rarely been studied. Characterization of neonatal septicemic hvKP/CR-hvKP strains in terms of resistance and virulence was carried out. Antibiotic susceptibility, molecular characterization, evaluation of clonality, in vitro virulence, and transmissibility of carbapenemase genes were evaluated. Whole-genome sequencing (WGS) and mouse lethality assays were performed on strains harboring pLVPK-associated markers. About one-fourth (26%, 28/107) of the studied strains, leading to mortality in 39% (11/28) of the infected neonates, were categorized as hvKP. hvKP-K2 was the prevalent pathotype (64.2%, 18/28), but K54 and K57 were also identified. Most strains were clonally diverse belonging to 12 sequence types, of which ST14 was most common. Majority of hvKPs possessed virulence determinants, strong biofilm-forming, and high serum resistance ability. Nine hvKPs were carbapenem-resistant, harboring blaNDM-1/blaNDM-5 on conjugative plasmids of different replicon types. Two NDM-1-producing high-risk clones, ST11 and ST15, had pLVPK-associated markers (rmpA, rmpA2, iroBCDEN, iucABCDiutA, and peg-344), of which one co-transferred the markers along with blaNDM-1. The 2 strains revealed high inter-genomic resemblance with the other hvKP reference genomes, and were lethal in mouse model. To the best of our knowledge, this study is the first to report on the NDM-1-producing hvKP ST11-K2 and ST15-K54 strains causing fatal neonatal sepsis. The presence of pLVPK-associated markers and blaNDM-1 in high-risk clones, and the co-transmission of these genes via conjugation calls for surveillance of these strains. IMPORTANCE Klebsiella pneumoniae is a leading cause of sepsis in newborns and adults. Among the 2 major pathotypes of K. pneumoniae, classical (cKP) and hypervirulent (hvKP), hvKP causes community-acquired severe fatal invasive infections in even healthy individuals, as it possesses several virulence factors. The lack of comprehensive studies on neonatal septicemic hvKPs prompted this work. Nearly 26% diverse hvKP strains were recovered possessing several resistance and virulence determinants. The majority of them exhibited strong biofilm-forming and high serum resistance ability. Nine of these strains were also carbapenem (last-resort antibiotic)-resistant, of which 2 high-risk clones (ST11-K2 and ST15-K54) harbored markers (pLVPK) noted for their virulence, and were lethal in the mouse model. Genome-level characterization of the high-risk clones showed resemblance with the other hvKP reference genomes. The presence of transmissible carbapenem-resistant gene, blaNDM, along with pLVPK-markers calls for vigilance, as most clinical microbiology laboratories do not test for them.

Deciphering the nitrate sources and processes in the Ganga river using dual isotopes of nitrate and Bayesian mixing model.

The dual isotopes of dissolved NO3- (n = 43) has been used to delineate the nitrate sources and N-cycling processes in the Ganga river. The proportional contribution of nitrate from different sources has been estimated using the Bayesian mixing model. The seasonal NO3- concentration in the lower stretch of the river Ganga varied between 4.1 and 64.1 µM with higher concentration during monsoon and post-monsoon season and lower concentration during the pre-monsoon and winter season. The temporal variation in the isotopic values ranged between +0.0 and +9.6‰ for δ15NNO3- and -1.2 to +11.0‰ for δ18ONO3-. The spatial NO3- concentration during the post-monsoon season varied between 23.2 and 57.7 µM, with higher values from the middle and lower values from the lower stretch of the river Ganga. The isotopic ratio during the post-monsoon season varied between -1.0 and +11.3‰ for δ15NNO3- and -4.6 to +5.2‰ for δ18ONO3-. The temporal dataset from the lower stretch of the river Ganga showed the dominance of nitrate derived from the nitrification of soil organic matter (SOM) (average ∼53.4%). The nitrate contribution from synthetic fertilizers was observed to be higher during the post-monsoon season (34.7 ± 23.4%) compared to that in the monsoon (25.5 ± 19.5%) and pre-monsoon (22.2 ± 19.6%) season. No significant seasonal variations were observed in the nitrate input from manure/sewage (∼13.9%). Spatial samples collected during the post-monsoon season showed higher contribution of synthetic fertilizer in the lower stretch (34.6 ± 22.7%) compared to the middle stretch (21.1 ± 18.2%), which indicates greater influence of the agricultural activity in the lower stretch. The dual isotope study of dissolved NO3- established that the nitrate in the Ganga river water is mostly derived from the nitrification of incoming organic compounds and is subsequently removed via assimilatory nitrate uptake. The study also emphasises significant nitrification and assimilatory nitrate removal processes operating in the mixing zone of the Ganga river and Hooghly estuary.

Metagenomic insights into surface water microbial communities of a South Asian mangrove ecosystem.

Estuaries are one of the most productive ecosystems and their productivity is maintained by resident microbial communities. Recent alterations driven by climate change have further escalated these stressors leading to the propagation of traits such as antibiotic resistance and heavy metal resistance in microbial communities. Surface water samples from eleven stations along the Thakuran and Matla estuaries of the Sundarbans Biosphere Reserve (SBR) of Sundarbans mangrove located in South Asia were sampled in monsoon (June) 2019 to elucidate resident microbial communities based on Nanopore sequencing. Metagenomic analyses revealed the widespread dominance of Proteobacteria across all the stations along with a high abundance of Firmicutes. Other phyla, including Euryarchaeota, Thaumarchaeota, Actinobacteria, Bacteroidetes and Cyanobacteria showed site-specific trends in abundance. Further taxonomic affiliations showed Gammaproteobacteria and Alphaproteobacteria to be dominant classes with high abundances of Bacilli in SBR_Stn58 and SBR_Stn113. Among the eukaryotic communities, the most abundant classes included Prasinophyceae, Saccharyomycetes and Sardariomycetes. Functional annotation showed metabolic activities such as carbohydrate, amino acid, nitrogen and phosphorus metabolisms to be uniformly distributed across all the studied stations. Pathways such as stress response, sulphur metabolism and motility-associated genes appeared in low abundances in SBR. Functional traits such as antibiotic resistance showed overwhelming dominance of genes involved in multidrug resistance along with widespread resistance towards commonly used antibiotics including Tetracycline, glycopeptide and aminoglycoside. Metal resistance genes including arsenic, nickel and copper were found in comparable abundances across the studied stations. The prevalence of ARG and MRG might indicate presence of pollutants and hint toward deteriorating ecosystem health status of Sundarbans mangrove.

An Updated Checklist of Free-living Marine Nematodes from Coastal India.

The present study provides an updated species list of free-living marine nematodes reported from coastal India (Coasts and Islands) based on the thorough consultation of literature published from 1956 to 2022. This exercise resulted in a total of 617 valid species belonging to 266 genera, 48 families, 21 superfamilies and 9 orders. Class Chromadorea comprises 487 species represented by 205 genera, while class Enoplea includes 130 species belonging to 61 genera. The most common family was Xyalidae, with 76 species and the least common families having a single species each were represented by Aegialoalaimidae, Rhadinematidae, Aphanolaimidae, Rhabditidae, Pandolaimidae and Rhabdodemaniidae. The checklist provides a robust framework for the distribution and biogeography of free-living marine nematodes from the Indian waters and could be used to relate with marine ecosystems of other countries.

Exploring changes in bacterioplankton community structure in response to tannic acid, a major component of mangrove litterfall of Sundarbans mangrove ecosystem: a laboratory mesocosm approach.

Tannic acid is a secondary compound produced by vascular plants and is a major component of mangrove litterfall. Tannic acid is water soluble, leaches out from mangrove litterfall and contributes to DOC and DON pools in adjacent estuaries. About 50% of the litterfall may be degraded and channelized into the marine microbial loop. The influence of tannic acid on bacterioplankton community structure was tested by setting up laboratory-based barrel experiments. Estuarine water from Stn3 of Sundarbans Biological Observatory Time Series (SBOTS) was enriched with tannic acid, and the change in concentration of dissolved nutrients was determined on a daily basis over a span of 15 days. Concentrations of tannic acid, gallic acid and other dissolved nutrients such as nitrate and ortho-phosphate were determined using a UV-Vis spectrophotometer. Tannic acid significantly affected the concentrations of gallic acid and dissolved nitrate in the barrels. Degradation of tannic acid was tracked by a decrease in concentration of tannic acid and generation of gallic acid. The influence of tannic acid on bacterioplankton community structure was analysed on the start (day 0), intermediate (day 3, day 5, day 7 and day 9) and end (day 15) of the experiment. Bacterioplankton community structure was elucidated by sequencing the V3-V4 region of 16S ribosomal RNA on an Illumina MiSeq platform. Proteobacteria was found to be the most dominant bacterial phylum in control and tannic acid-enriched barrels (barrels 1 and 2) on day 0. With the progression of experiment, the abundance of Proteobacteria altered significantly in the control barrel indicating the possible role of this phylum in the breakdown of tannic acid within estuarine mangroves. The abundance of Proteobacteria in the tannic acid-enriched barrels remained high, indicating that members of Proteobacteria may be capable of using tannic acid as a source of carbon and nitrogen. Tannic acid appeared to inhibit most of the other bacterioplankton phyla including Actinobacteria, Acidobacteria and Verrucomicrobia that existed in large abundance in the control barrel on day 15 but were almost absent in the tannic acid-enriched barrels. At class level, Bacteroides was found to be present in highest abundance in the tannic acid-enriched barrels. Tannic acid appeared to strongly influence the abundant bacterioplankton phyla and families as indicated by Pearson's correlation coefficient and non-metric multidimensional scaling ordination plots. Gallic acid is one of the final products of tannic acid degradation. Breakdown of tannic acid could influence the marine nitrogen and carbon cycling by releasing DON and DOC, respectively, into the adjacent estuaries. Information of breakdown and remineralization of components of litterfall such as tannic acid would also be important for calculation of carbon and nitrogen budgets of coastal ecosystems including in mangroves.

From Small Molecules to Synthesized Polymers: Potential Role in Combating Amyloidogenic Disorders.

The concept of developing novel anti-amyloid inhibitors in the scientific community has engrossed remarkable research interests and embraced significant potential to resolve numerous pathological conditions including neurological as well as non-neuropathic disorders associated with amyloid protein aggregation. These pathological conditions have harmful effects on cellular activities which include malfunctioning of organs and tissue, cellular impairment, etc. To date, different types of small molecular probes like polyphenolic compounds, nanomaterials, surfactants, etc. have been developed to address these issues. Recently synthetic polymeric materials are extensively investigated to explore their role in the protein aggregation pathway. On the basis of these perspectives, in this review article, we have comprehensively summarized the current perspectives on protein misfolding and aggregation and importance of therapeutic approaches in designing novel effective inhibitors. The main purpose of this review article is to provide a detailed perspective of the current landscape as well as trailblazing voyage of various inhibitors ranging from small molecular probes to polymeric scaffolds in the field of protein misfolding and aggregation. A particular emphasis is given on the structural role and molecular mechanistic pathway involved in modulating the aggregation pathway to further inspire the researchers and shed light in this bright research field.

Myceligenerans indicum sp. nov., an actinobacterium isolated from mangrove sediment of Sundarbans, India.

A new actinobacterial species of the genus Myceligenerans has been isolated from the intertidal sediment of Indian Sundarbans mangrove ecosystem. The isolate has been characterized based on polyphasic approaches. The isolate exhibit well-developed substrate mycelia along with the presence of cocci- and rod-shaped elements. The organism can grow across a wide range of temperature, salinity, and pH as well as on different carbon sources. Phylogenetic analyses based on 16S rRNA showed that this isolate is closely related to Myceligenerans salitolerans XHU 5031 (99% identity; 100% coverage). Presence of ketosynthase domain representing polyketide synthases in the isolate provides evidence of its potential ability to produce secondary metabolites. Multigene phylogeny based on atpD and rpoB gene sequences confirmed it as a new species within the family Promicromonosporaceae (Phylum Actinobacteria). The DNA G + C content of the isolate has been determined as 72 mol%. The peptidoglycan type was A4α and the whole-cell hydrolysates contained glucose, galactose, and mannose. The polar lipids were represented by diphosphatidylglycerol, one unknown phospholipid and one unknown glycolipid. Major fatty acids present in the isolate are anteiso-C15, iso-C15, iso-C16, and anteiso-C17. Whole-genome sequence indicates the size of genome is ~ 5 Mbp. GGDC (%), orthoANIu (%), and AAI of I2 genome indicated 28.9%, 77.44% and 0.859 identity with the genome of Myceligenerans xiligouense strain DSM 15,700. The isolate I2 has been proposed as a new species, Myceligenerans indicum sp. nov. The genome sequence has been deposited to GenBank/ENA/DDBJ under the accession number JABBYC000000000.

Datasets of surface water microbial populations from two anthropogenically impacted sites on the Bhagirathi-Hooghly River.

The Bhagirathi-Hooghly River, part of the River Ganga, flows along densely urbanized areas in West Bengal, India. The River water is extensively used for household activities, human consumption including bathing, social purposes and multifaceted industrial usage. As a result of discharge of untreated municipal sewage and effluents from industries there is evidence of heavy pollution in this River. Two urbanized sites on the Bhagirathi-Hooghly River, namely Kalyani and Kolkata, were sampled to elucidate the resident microbial communities in lieu of anthropogenic forcing with respect to pollution. The Kalyani station (Kal_Stn1) lies upstream to the Kolkata station (Kol_Stn7) and are approximate 50 km away from each other and located along the bank of Bhagirathi-Hooghly River. Sampling was undertaken in monsoon (September 2018). In situ environmental parameters were measured during sampling and dissolved nutrients were estimated from formalin fixed filtered surface water along with pesticides analysis. One litre surface water sample was collected from each station and environmental DNA was sequenced to identify resident microbial communities (bacterioplankton and oxygenic photoautrophs-phytoplankton). The bacterioplankton community structure was elucidated by sequencing the V4 region of the 16S rDNA on an Illumina MiSeq platform. Proteobacteria was found to be the most abundant bacterioplankton phylum in both sampling stations. Similar to bacterioplankton, variation in oxygenic photoautotrophic community structure including phytoplankton forms was found at phylum, class and family levels. The phytoplankton communities were elucidated by sequencing the V9 region of the 18S rDNA on an Illumina MiSeq platform. Chrysophyta was found to be the most abundant phytoplankton phylum identified from both stations, followed by Chlorophyta and other groups. Variation in phytoplankton community structure between the stations was distinct at phylum, class and family levels.

Diversity of Betaproteobacteria revealed by novel primers suggests their role in arsenic cycling.

High arsenic concentration in groundwater is a severe environmental problem affecting human health, particularly in countries of South and South-East Asia. The Bengal Delta Plain (BDP) distributed within India and Bangladesh is a major arsenic-affected region where groundwater is the primary source of drinking water. Previous studies have indicated that members of the bacterial class Betaproteobacteria constitute a major fraction of the microbial community in many of the aquifers within this region. Bacteria belonging to this class are known to be involved in redox cycling of arsenic as well as other metals such iron and manganese, thereby impacting arsenic mobilization and immobilization. While microbial diversity in arsenic-contaminated environments is generally assessed using universal 16S rRNA gene primers, targeted evaluation of Betaproteobacteria diversity remains poorly constrained. In this study, bacterial diversity was investigated in the groundwater from two shallow aquifers (West Bengal, India) based on 16S rRNA gene clone libraries and sequencing using a custom-designed pair of primers specific to Betaproteobacteria. Specificity of the primers was confirmed in silico as well as by the absence of PCR amplification of other bacterial classes. Four major families (Burkholderiaceae, Comamonadaceae, Gallionellaceae and Rhodocyclaceae) were detected among which members of Burkholderiaceae represented 59% and 71% of the total community in each aquifer. The four OTUs (operational taxonomic units; 97% sequence identity) within Burkholderiaceae were close phylogenetic relatives of bacteria within the genus Burkholderia known to solubilize phosphate minerals. Additionally, the OTUs belonging to Gallionellaceae were closely related to the members of the genera Gallionella and Sideroxydans, known to oxidize iron under microaerophilic conditions. These results suggest that members of Betaproteobacteria can potentially influence iron and phosphorus cycling which can influence biogeochemistry in arsenic-contaminated aquifers of the BDP.

Side-Chain Proline-Based Polymers as Effective Inhibitors for In Vitro Aggregation of Insulin.

Insulin fibril formation is considered as the hallmark of several debilitating pathological conditions. To develop effective therapeutics that are able to control the amyloidogenesis process and inhibit fibril formation, herein we have designed a side-chain proline (Pro)-based homopolymer and block copolymers through the reversible addition-fragmentation chain transfer (RAFT) polymerization technique and further explored their obligatory role in the in vitro insulin fibrillation process. Using a variety of biophysical tools, including turbidity measurements, thioflavin T (ThT) fluorescence kinetics, tyrosine (Tyr) fluorescence study, Nile red (NR) fluorescence assay, dynamic light scattering (DLS) study, circular dichroism (CD) measurements, and isothermal titration calorimetry (ITC) techniques, we demonstrated that Pro-based polymers can significantly inhibit the insulin fibrillation process. Among them, the Pro-based homopolymer acts as the most potent inhibitor of insulin fibrillation as confirmed by ThT assay, CD study, and transmission electron microscopic (TEM) analysis. Tyrosine fluorescence measurements and NR fluorescence assay revealed that hydrophobic interactions are the crucial factor that mainly controls the inhibition process. Apart from hydrophobic interactions, polar interactions may also be responsible for the inhibition process as evaluated by ITC study.

Vibrio chemaguriensis sp. nov., from Sundarbans, Bay of Bengal.

A new species of Vibrio (annotated as SBOTS_Iso1) was isolated in August 2014 from the Stn1 located in Chemaguri creek of Sundarbans mangrove ecoregion and taxonomically characterized using a polyphasic approach. Phenotypic analysis including biochemical tests and growth across a wide range of salinities indicated the typical estuarine characteristics of this new species. The bacterium was Gram negative, rod-shaped, oxidase and catalase negative and grows in the presence of NaCl. FAME analysis indicated 31.7% of the cellular fatty acids to be made up of 16:1 ω7c/16:1 ω6c. Amplification and sequencing of 16S rRNA and multilocus sequence analysis of four loci (2040 bp; rpoA, topA, mreB, pyrH) and additional sequence data of ftsZ, atpD, ompW and rpoB genes showed this isolate to be a member of Harveyi clade of the genus Vibrio. The closest phylogenetic neighbour was Vibrio alginolyticus ATCC 17749T with 96.8% similarity. Whole-genome sequence data indicates the presence of ~ 5 Mbp genome. GGDC, orthoANIu and AAI indicated 45%, 92% and 0.962 identity respectively with genome of Vibrio alginolyticus ATCC 17749T. The isolate SBOTS_Iso1 has been named Vibrio chemaguriensis sp. nov. on the name of the site from where it was first isolated.

Matrix-Assisted Regulation of Antimicrobial Properties: Mechanistic Elucidation with Ciprofloxacin-Based Polymeric Hydrogel Against Vibrio Species.

The design of a new drug material through modification of some well-known antibiotics to combat pathogenic bacteria must include a complete understanding of matrix regulation because the human body consists of primarily three types of matrices, that is, solid, semisolid, and liquid, all of which have a tendency to regulate antibacterial efficacy along with the bactericidal mechanism of several antimicrobial agents. Herein, matrix-dependent action of ciprofloxacin-based polymeric hydrogel scaffold was explored against a new species of Vibrio, namely, Vibrio chemaguriensis Iso1 ( V. chemaguriensis), which is resistant to most of the common antibiotics and possess genes that can be linked to pathogenicity. Ciprofloxacin was attached to the polymeric system consisting of hydrophilic polyethylene glycol methyl ether methacrylate (PEGMA) and zwitterionic sulphabetaine methacrylate (SBMA) with an antifouling nature via covalent linkage leading to effective polymer antibiotic conjugates (PACs) with linear and hyperbranched architectures. The hyperbranched PAC was transformed to a polymeric gel exhibiting greater antibacterial efficacy in solid matrix than that of the liquid one with a complete bactericidal effect and rod to spherical switching of bacterial cell followed by chain formation via "dual" contact activity and release mechanism through sustained removal of thiol-terminated ciprofloxacin fragment along with an equilibrium swelling and deswelling process. Lower killing efficacy was displayed in the liquid matrix with an intact cell morphology that is due to lack of forced contact between the cell wall and gel surface as well as entrapment of released bioactive fragment via an additional thick exopolysaccharide (EPS) layer, which represents a great challenge to modern medical sciences.