No abstract

Ichthyenterobacterium magnum gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from olive flounder (Paralichthys olivaceus) A novel marine bacterium isolated from the intestine of cultured flounder (Paralichthys olivaceus) was studied by using a polyphasic taxonomic approach. The isolate was Gram-stain-negative, pleomorphic, aerobic, yellow and oxidase-and catalase-negative. Phylogenetic analysis of 16S rRNA gene sequences indicated that isolate Th6T formed a distinct branch within the family Flavobacteriaceae and showed 96.6 % similarity to its closest relative, Bizionia hallyeonensis Ty7T . The DNA G+C content was 29 mol%. The major respiratory quinone was MK-6. The predominant fatty acids were iso-C 15 : 1 G, iso-C 15 : 0 , iso-C 15 : 0 3-OH, iso-C 17 : 0 3-OH and summed feature 3 (C 15 : 1 v6c and/or C 16 : 1 v7c). On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, the novel bacterium has been assigned to a novel species of a new genus for which the name Ichthyenterobacterium magnum gen. nov., sp. nov. is proposed. The type strain is Th6 T (5JCM 18636 T 5KCTC 32140 T ).

Over the past few decades, anammox bacteria have been recognized as key players that contribute significantly to the release of large amounts of nitrogen in the global marine nitrogen cycle. In the present study, the diversity, community composition, and abundance of anammox bacteria from the sediments of four diverse regions in the north marginal seas in China were determined via clone library construction and a quantitative PCR analysis. The clone libraries retrieved by the 16S rRNA gene and Hzo gene markers indicated that “Candidatus Scalindua” was the predominant group throughout the sites examined. The 16S rRNA gene clone libraries revealed exceptional diversity by identifying two potential novel anammox clades, as evidenced by the high sequence similarities between these two clades and known anammox genera, and their unique phylogenetic positions with high bootstrap values. However, their potential roles in the anammox reaction need to be validated. Six novel members of Planctomycetes, divergent from the known genera of anammox bacteria, were also detected. A phylogenetic analysis by Hzo protein sequences revealed the existence of two known genera, i.e., “Candidatus Jettenia” and “Candidatus Anammoxoglobus”, which are rarely captured from marine sediments. Among all ecological parameters investigated, the distribution patterns and composition of anammox bacteria were found to be influenced by salinity, total organic matter, and temperature. The abundance of the anammox bacterial 16S rRNA gene from the sites examined ranged between 3.95×105 and 9.21×105 copies g−1 wet sediment and positively correlated with the median size of the sediment sample.

Some soil microbes, with their diverse inhabitance, biologically active metabolites, and endospore formation, gave them characteristic predominance and recognition among other microbial communities. The present study collected ten soil samples from green land, agricultural and marshy soil sites of Khyber Pakhtunkhwa, Pakistan. After culturing on described media, the bacterial isolates were identified through phenotypic, biochemical and phylogenetic analysis. Our phylogenetic analysis revealed three bacterial isolates, A6S7, A1S6, and A1S10, showing 99% nucleotides sequence similarity with Brevibacillus formosus, Bacillus Subtilis and Paenibacillus dendritiformis. The crude extract was prepared from bacterial isolates to assess the anti-bacterial potential against various targeted multidrug-resistant strains (MDRS), including Acinetobacter baumannii (ATCC 19606), Methicillin-resistant Staphylococcus aureus (MRSA) (BAA-1683), Klebsiella pneumoniae (ATCC 13883), Pseudomonas aeruginosa (BAA-2108), Staphylococcus aureus (ATCC 292013), Escherichia coli (ATCC25922) and Salmonella typhi (ATCC 14028). Our analysis revealed that all bacterial extracts possess activity against Gram-negative and Gram-positive bacteria at a concentration of 5 mg/mL, efficiently restricting the growth of E. coli compared with positive control ciprofloxacin. The study concluded that the identified species have the potential to produce antimicrobial compounds which can be used to control different microbial infections, especially MDRS. Moreover, the analysis of the bacterial extracts through GC-MS indicated the presence of different antimicrobial compounds such as propanoic acid, oxalic acid, phenol and hexadecanoic acid.