Sporosarcina hypophthalmichthys sp. nov. Isolated From Gastrointestinal Tract of Fish Hypophthalmichthys molitrix (Valenciennes, 1844).

A rod-shaped, motile, Gram-stain-positive bacterial strain RKN2T, was isolated from gut of silver carp (Hypophthalmichthys molitrix) residing in Gobindsagar reservoir, Himachal Pradesh, India. Having the greatest sequence similarity to Sporosarcina koreensis F73T (98.51%), Sporosarcina luteola Y1T (98.4%) and Sporosarcina aquimarina SW28T (98.36%), the 16S rRNA gene phylogeny confirmed the belonging of strain RKN2T to genus Sporosarcina. Digital DNA-DNA hybridization values were 21.7%, 20.6%, and 19.2%, and average nucleotide identity values were 76.42%, 80.16%, 76.51%, of strain RKN2T with Sporosarcina koreensis F73T, Sporosarcina luteola Y1T, and Sporosarcina aquimarina SW28T, respectively. The genomic analysis of strain RKN2T showed various biological properties including nitrate reduction, genes responsible for carbohydrate-active enzymes production, antimicrobial compounds, as well as potential metabolism of aromatic compounds and heavy metals. G+C composition of RKN2T genome was 52.7%. This strain can grow in temperatures between 10°C and 40°C (optimum, 28°C-30°C), NaCl concentrations up to 6.0% (w/v), and 6.0-8.0 (optimum, 6.5-7.5) pH range. MK-7 was the dominant respiratory quinone, A-4 type cell wall peptidoglycan was present with anteiso-C15:0, iso-C15: 0, and anteiso-C17:0 being the major fatty acids and Lys-Glu being main amino acids. Diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine were the strain RKN2T's three main polar lipids. The strain is a novel species under genus Sporosarcina based on polyphasic approach and the name Sporosarcina hypophthalmichthys sp. nov. is given for strain RKN2T. RKN2T is a type strain (= MCC 4365T = JCM34522T = CCM9112T).

Mitochondrial DNA reveals shallow population genetic structure in economically important Cyprinid fish Labeo rohita (Hamilton, 1822) from South and Southeast Asia.

BACKGROUND: Assessment of genetic diversity and population genetic structure is important for species that are economically important, threatened, and are at global conservation priority. Analysis of mitochondrial DNA is broadly used in species identification and population genetics studies due to the availability of sufficient reference data and better evolutionary dynamics for phylogeographic investigation. Labeo rohita (Rohu) is an economically important species cultured under carp polyculture systems in Asia. The present study explores the genetic diversity, phylogeography, and population structure of L. rohita from different countries using cytochrome oxidase subunit I (COI) gene. METHODS AND RESULTS: A total of 17 L. rohita specimens were sampled from River Beas, India. For the genetic study, we amplified and sequenced COI mitochondrial DNA region. The obtained genetic data was combined with 268 COI records available in the NCBI and BOLD databases originating from multiple populations/countries across South and Southeast Asia. As a result, 33 haplotypes were identified that displayed low nucleotide (π = 0.0233) and moderate haplotype diversity (Hd = 0.523). Tajima (D) was found to be negative (P > 0.05), whereas Fu's Fs showed a positive value (P > 0.05). The overall FST value between studied populations was 0.481 (P < 0.05). CONCLUSION: AMOVA analysis indicated higher variation within than among the population examined. The neutrality tests suggested the presence of rare haplotypes and stable demography within studied populations of L. rohita. The Bayesian skyline plot indicated steady population growth until 1 Mya followed by population decline, whereas FST values indicated significant genetic differentiation. High heterogeneity was observed in the Pakistan population which could be indicative of long-term isolation and excessive culturing to meet market demands. The present results are the first global comparative analysis of L. rohita and pave the way forward for detailed genomic and ecological studies aimed at the development of improved stock and effective conservation plans. The study also makes recommendations to conserve the genetic integrity of wild species from aquaculture-reared fishes.

Genome-resolved metagenomics revealed metal-resistance, geochemical cycles in a Himalayan hot spring.

The hot spring microbiome is a complex assemblage of micro- and macro-organisms; however, the understanding and projection of enzymatic repertoire that access earth's integral ecosystem processes remains ambivalent. Here, the Khirganga hot spring characterized with white microbial mat and ions rich in sulfate, chlorine, sodium, and magnesium ions is investigated and displayed the examination of 41 high and medium qualified metagenome-assembled genomes (MAGs) belonged to at least 12 bacterial and 2 archaeal phyla which aids to drive sulfur, oxygen, iron, and nitrogen cycles with metabolic mechanisms involved in heavy metal tolerance. These MAGs possess over 1749 genes putatively involved in crucial metabolism of elements viz. nitrogen, phosphorus, and sulfur and 598 genes encoding enzymes for czc efflux system, chromium, arsenic, and copper heavy metals resistance. The MAGs also constitute 229 biosynthetic gene clusters classified abundantly as bacteriocins and terpenes. The metabolic roles possibly involved in altering linkages in nitrogen biogeochemical cycles and explored a discerned rate of carbon fixation exclusively in archaeal member Methanospirillum hungatei inhabited in microbial mat. Higher Pfam entropy scores of biogeochemical cycling in Proteobacteria members assuring their major contribution in assimilation of ammonia and sequestration of nitrate and sulfate components as electron acceptors. This study will readily improve the understanding of the composite relationship between bacterial species owning metal resistance genes (MRGs) and underline the exploration of adaptive mechanism of these MAGs in multi-metal contaminated environment. KEY POINTS: • Identification of 41 novel bacterial and archaeal species in habitats of hot spring • Genome-resolved metagenomics revealed MRGs (n = 598) against Cr, Co, Zn, Cd, As, and Cu • Highest entropies of N (0.48) and Fe (0.44) cycles were detected within the MAGs.

Taxonomic and genomic characterization of Sporosarcina cyprini sp. nov., moderately tolerant of Cr+6 and Cd+2 isolated from the gut of invasive fish Cyprinus carpio var. communis (Linn., 1758).

A Gram-stain-positive, motile, and rod-shaped bacterium, designated as strain MB25T, was isolated from the gut of Cyprinus carpio from the highly polluted river Yamuna, India. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain MB25T belonged to the genus Sporosarcina, sharing the highest sequence similarity with S. luteola Y1T (98.98%) and S. koreensis S-K12T (98.91%). Digital DNA-DNA hybridization and average nucleotide identity values of strain MB25T with strain Y1T and S-K12T were 18.9, 77.69, and 18.2, 76.80 respectively. Genome analysis of strain MB25T revealed its biotechnological properties such as tolerance to potent heavy metals, genes for the production of carbohydrate-active enzymes, antimicrobial compounds, and also degradation of aromatic compounds. The G + C content of strain MB25T genome was 45%. Growth observed at 10-40 °C (optimum, 28-30 °C), pH 6.0-8.5 (optimum pH 7.5-8.0); NaCl concentrations up to 6.0% (w/v). The dominant respiratory quinone was MK-7, cell wall peptidoglycan is of the A-4 type containing amino acids Lys-Glu and the major fatty acids are anteiso-C11:0 and iso-C15: 0. The major polar lipids of strain MB25T are diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. On the basis of phenotypic, chemotaxonomic, phylogenetic, and phylogenomic data, strain MB25T represents a novel species of the genus Sporosarcina, for which the name Sporosarcina cyprini sp. nov. is proposed. The type strain is MB25T (= MCC 4366 T = JCM 34521 T = CCM 9113 T).

Metagenomic insights to understand the role of polluted river Yamuna in shaping the gut microbial communities of two invasive fish species.

The gastrointestinal microbial community plays a crucial role in host health, immunity, protection, development and provides nutrients to the host. The rising human-induced pollution and heavy metal contamination in all aquatic systems globally has led us to explore the gut microbial diversity of two exotic invasive fish Cyprinus carpio (Linnaeus, 1858) and Oreochromis niloticus (Linnaeus,1857) from river Yamuna, India. These fishes are aquatic bioindicators with high demographic resilience. Exploring these associations would pave the way for addressing problems that inhabitant fishes are facing due to the increasing pollution load in the River Yamuna. Based on 16S rRNA gene amplicon sequencing, our results deliver comparative information on the gut microbiome of these fishes and highlight connotations between the microbiome of gut and water samples. The gut of C. carpio and O. niloticus was dominated by phyla Proteobacteria whereas Bacteroidetes dominated the water sample. Microbial communities showed predicted roles such as pathogenicity (Escherichia-Shigella, Aeromonas veronii, Vibrio cholerae, Streptococcus iniae, Flavobacterium columnare, Klebsiella pneumoniae, Mycobacterium sp.), probiotic applications (Bacillus velezensis, Lactobacillus plantarum, Enterococcus faecalis, Bifidobacterium longum, Lactococcus lactis, Leuconostoc falkenbergense) and involvement in sewage and organic matter decomposition (Nitrosomonas sp., Methanosaeta harundinacea, Dechloromonas agitata, Thauera humireducens, Zoogloea ramigera). Heavy metal degrading members (Leucobacter chromiireducens, Pseudomonas fluorescens, P. aeruginosa, Klebsiella pneumoniae, and Micrococcus luteus) were detected in gut microbiome samples thus supporting the notion that fish shapes its gut microbiota with changing ecology. Functional profiling showed that microbial communities are specialized in metabolic functions thus reflecting the dietary profile of these invasive fishes.

Gut milieu shapes the bacterial communities of invasive silver carp.

Silver carp is an invasive fish present in the Gobindsagar reservoir, India and has a profound impact on aquaculture. Understanding taxonomic diversity and functional attributes of gut microbiota will provide insights into the important role of bacteria in metabolism of silver carp that facilitated invasion of this exotic species. Microbial composition in foregut, midgut, hindgut and water samples was analysed using 16S rRNA gene amplicon sequencing. The bacterial communities of water samples were distinct from gut microbiota, and unique microbial assemblages were present in different regions of gut depicting profound impact of gut environment on microflora. Proteobacteria was the most abundant phyla across all samples. Ecological network analysis showed dominance of competitive interactions within posteriors region of the gut, promoting niche specialization. Predictive functional profiling revealed the microbiota specialized in digestive functions in different regions of the gut, which also reflects the dietary profile of silver carp.

Unveiling the ecotoxicological impact of microplastics on organisms - the persistent organic pollutant (POP): A comprehensive review.

Microplastics have been ubiquitous in our environment for decades, and numerous studies have revealed their extensive dispersion, reaching far beyond the surface of the land, soil, aquatic ecosystems. They have infiltrated the food-chain, the food web, even the air we breathe, as well as the water we drink. Microplastics have been detected in the food we consume, acting as vectors for hazardous chemicals that adhere to their hydrophobic surfaces. This can result in the transfer of these chemicals to the aquatic life, posing a threat to their well-being. The release of microplastics into different environmental settings can give rise to various eco-toxicological implications. The substantial body of literature has led scientists to the consensus that microplastic pollution is a global problem with the potential to impact virtually any type of ecosystem. This paper aims to discuss crucial information regarding the occurrence, accumulation, and ecological effects of microplastics on organisms. It also highlights the new and emerging disease named "Plasticosis" that is directly linked to microplastics and its toxicological effects like permanent scarring and long-term inflammation in the digestive system of the seabirds. By comprehending the behaviour of these microplastic pollutants in diverse habitats and evaluating their ecological consequences, it becomes possible to facilitate a better understanding of this toxicological issue.

Challenges and effective tracking down strategies of antibiotic contamination in aquatic ecosystem.

A growing environmental concern revolves around the widespread use of medicines, particularly antibiotics, which adversely impact water quality and various life forms. The unregulated production and utilization of antibiotics not only affect non-targeted organisms but also exert significant evolutionary pressures, leading to the rapid development of antimicrobial resistance (AMR) in bacterial communities. To address this issue, global studies have been conducted to assess the prevalence and quantities of antibiotics in various environmental components including freshwater, ocean, local sewage, and fish. These studies aim to establish effective analytical methods for identifying and measuring antibiotic residues in environmental matrices that might enable authorities to establish norms for the containment and disposal of antibiotics. This article offers a comprehensive overview of methods used to extract antibiotics from environmental matrices exploring purification techniques such as liquid-liquid extraction, solid-phase extraction, green extraction techniques, and concentration methods like lyophilization and rotary evaporation. It further highlights qualitative and quantitative analysis methods, high-performance liquid chromatography, ultra-high-performance liquid chromatography, and liquid chromatography-tandem along with analytical methods such as UV-Vis and tandem mass spectrometry for detecting and measuring antibiotics. Urgency is underscored for proactive strategies to curb antibiotic contamination, safeguarding the integrity of aquatic ecosystems and public health on a global scale.

Riverine pollution influences the intraspecific variation in the gut microbiome of an invasive fish, Cyprinus carpio (Linn., 1758).

Humans are significantly impacting riverine systems worldwide, prompting us to investigate the effects of water pollution on the gut microbiome of Cyprinus carpio (common carp). Using 16S rRNA gene sequencing, we compared the gut microbiomes of common carp from two sites along river Yamuna with different pollution levels. Water pollution significantly altered the fish gut microbiome structure and microbial composition. Proteobacteria dominated in both sampling sites, while Bacteroidota prevailed in polluted water samples, indicating sewage and fecal contamination. Less polluted samples exhibited Verrucomicrobiae and Planctomycetes, negatively correlated with pollution levels. The polluted site had higher prevalence of potentially pathogenic and heavy metal-resistant bacteria, as well as microbial communities associated with wastewater treatment systems. Functional prediction highlighted the significant role of the gut microbiome in digestion and metabolism, with active enzymes for breaking down various organic substances. Biosynthetic pathways for leucine, valine, and isoleucine were present in both sites, known to be involved fish immunity. The host maintained a stable and diverse bacterial consortium, while microbial diversity became more specialized due to human activities, adapting to anthropogenic stress and selection pressures. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03747-0.

Metagenome-assembled genomes recovered from the datasets of a high-altitude Himalayan hot spring Khirganga, Himachal Pradesh, India.

Khirganga, a pristine hot spring that lies in the Parvati Valley within the Northern Himalayas characterised with unique white colour microbial mat and divine water with healing abilities. Here, we report 41 metagenome-assembled genomes (MAGs) reconstructed from the microbial mat, sediment and water samples of hot spring passed through Genome Standards Consortium (GSC) and Minimum Information of Metagenome-assembled Genome (MIMAG).