Mucilaginibacter formosus sp. nov., a bacterium isolated from road-side soil

Bacterial mediated green synthesis of silver nanoparticles and their antibacterial and antifungal activities against drug-resistant pathogens

In the healthcare sector, the production of bioactive silver nanoparticles (AgNPs) with antimicrobial properties is of great importance. In this study, a novel bacterial strain, Paenibacillus sp. MAHUQ-63, was identified as a potential candidate for facile and rapid biosynthesis of AgNPs. The synthesized AgNPs were used to control the growth of human pathogens, Salmonella Enteritidis and Candida albicans. The bacterial culture supernatant was used to synthesize the nanoparticles (NPs). Field emission transmission electron microscope examination showed spherical-shaped NPs with 15-55 nm in size. Fourier transform-infrared analysis identified various functional groups. The synthesized AgNPs demonstrated remarkable activity against S. Enteritidis and C. albicans. The zones of inhibition for 100 µl (0.5 mg ml-1) of AgNPs against S. Enteritidis and C. albicans were 18.0 ± 1.0 and 19.5 ± 1.3 mm, respectively. The minimum inhibitory concentrations were 25.0 and 12.5 µg ml-1 against S. Enteritidis and C. albicans, respectively. Additionally, the minimum bactericidal concentrations were 25.0 µg ml-1 against both pathogenic microbes. The field emission scanning electron microscopy analysis showed that the treatment of AgNPs caused morphological and structural damage to both S. Enteritidis and C. albicans. Therefore, these AgNPs can be used as a new and effective antimicrobial agent.

Mucilaginibacter rivuli sp. nov., isolated from a water rivulet

Strain HMF5004T was isolated from a rivulet located in Yongin, Republic of Korea. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HMF5004T belonged to the genus Mucilaginibacter . Strain HMF5004T was closely related to Mucilaginibacter paludis (97.7%) and Mucilaginibacter gracilis (97.2%). The values of average nucleotide identity and digital DNA–DNA hybridization between strain HMF5004T and M. paludis were 72.8 and 19.2 %, respectively. Cells of strain HMF5004T were Gram-stain-negative, rod-shaped, non-motile, catalase-positive and oxidase-positive. The DNA G+C content of strain HMF5004T was 42.4 mol%. Strain HMF5004T had menaquinone-7 as a major quinone. The major cellular fatty acids included iso-C15 : 0, summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c) and anteiso-C15 : 0. The polar lipids of strain HMF5004T contained phosphatidylethanolamine, five unidentified aminolipids, one unidentified aminophospholipid and four unidentified polar lipids. On the basis of the evidence presented in this polyphasic taxonomic study, strain HMF5004T is considered to represent a novel species for which the name Mucilaginibacter rivuli sp. nov. is proposed. The type strain is HMF5004T (=KCTC 82633T=NBRC 115091T).

Identification of Mucilaginibacter conchicola sp. nov., Mucilaginibacter achroorhodeus sp. nov. and Mucilaginibacter pallidiroseus sp. nov. and emended description of the genus Mucilaginibacter

Three chitinolytic, Gram-negative, light pink, capsule-forming, rod-shaped bacterial strains with gliding motion (MYSH2T, MJ1aT and dk17T) were isolated from seashells, soil and foxtail, respectively. Phylogenetic analysis of the 16S rRNA gene sequences and concatenated alignment of 92 core genes indicated that strains MYSH2T, MJ1aT and dk17T were novel species of the genus Mucilaginibacter and exhibited a high 16S rRNA sequence similarity (i.e. more than 97.2 %) among each other. These novel strains contained summed feature 3 (C16:1 ω7c and/or C16:1 ω6), iso-C15:0 and MK-7 as the predominant fatty acids and menaquinone. According to the CAZys coding gene of KAAS, MYSH2T and MJ1aT were interpreted as strains containing both GH18 and 19 family coding genes, except for dk17T, which shows only GH19 family genes. These strains likely degrade chitin to chitobiose or directly to N-acetyl-d-glucosamine, which may enhance their chitinolytic capacity, thus making these stains potentially useful for industrial chitin degradation. Based on distinct morphological, physiological, chemotaxonomic and phylogenetic differences from their closest phylogenetic neighbours, we propose that strains MYSH2T, MJ1aT and dk17T represent three novel species in the genus Mucilaginibacter , for which the names Mucilaginibacter conchicola sp. nov. (=KACC 19716T=JCM 32787T), Mucilaginibacter achroorhodeus sp. nov. (=KACC 19906T=NBRC 113667T) and Mucilaginibacter pallidiroseus sp. nov. (=KACC 19907T=NBRC 113666T) are proposed. An emended description of the genus Mucilaginibacter is proposed.

Cocaine esterase occurrence in global wastewater microbiomes and potential for biotransformation of novel psychoactive substances

The analysis of drugs in wastewater for forensic purposes has been constantly increasing and the investigation of the potential interaction between drugs or metabolites and sewage microbiota is important. The results demonstrated that cocaine esterase genes were widely distributed in 1142 global wastewater samples collected from 64 countries and linked to several bacterial species. In addition, in silico predictions indicated that carfentanil, 4F-MDMB-BINACA, 5F-MDMB-PICA, MDMB-4en-PINACA and mitragynine might also undergo microbial hydrolysis, in a similar fashion of cocaine degradation by cocaine esterase. In conclusion, it was demonstrated the microbial potential to hydrolyze drugs of abuse in wastewater environments, contributing to the critical evaluation of potential metabolites as biomarkers for microbial and human transformation of drugs in wastewater.

Ecofriendly Synthesis of Silver Nanoparticles by Terrabacter humi sp. nov. and Their Antibacterial Application against Antibiotic-Resistant Pathogens

It is essential to develop and discover alternative eco-friendly antibacterial agents due to the emergence of multi-drug-resistant microorganisms. In this study, we isolated and characterized a novel bacterium named Terrabacter humi MAHUQ-38^T, utilized for the eco-friendly synthesis of silver nanoparticles (AgNPs) and the synthesized AgNPs were used to control multi-drug-resistant microorganisms. The novel strain was Gram stain positive, strictly aerobic, milky white colored, rod shaped and non-motile. The optimal growth temperature, pH and NaCl concentration were 30 °C, 6.5 and 0%, respectively. Based on 16S rRNA gene sequence, strain MAHUQ-38^T belongs to the genus Terrabacter and is most closely related to several Terrabacter type strains (98.2%-98.8%). Terrabacter humi MAHUQ-38^T had a genome of 5,156,829 bp long (19 contigs) with 4555 protein-coding genes, 48 tRNA and 5 rRNA genes. The culture supernatant of strain MAHUQ-38^T was used for the eco-friendly and facile synthesis of AgNPs. The transmission electron microscopy (TEM) image showed the spherical shape of AgNPs with a size of 6 to 24 nm, and the Fourier transform infrared (FTIR) analysis revealed the functional groups responsible for the synthesis of AgNPs. The synthesized AgNPs exhibited strong anti-bacterial activity against multi-drug-resistant pathogens, Escherichia coli and Pseudomonas aeruginosa. Minimal inhibitory/bactericidal concentrations against E. coli and P. aeruginosa were 6.25/50 and 12.5/50 μg/mL, respectively. The AgNPs altered the cell morphology and damaged the cell membrane of pathogens. This study encourages the use of Terrabacter humi for the ecofriendly synthesis of AgNPs to control multi-drug-resistant microorganisms.

Ganoderma lucidum cultivation affect microbial community structure of soil, wood segments and tree roots

The popular medicinal mushroom Ganoderma lucidum (Fr.) Karst. [Ling Zhi] has been widely used for the general promotion of health and longevity in Asian countries. Continuous cultivation may affect soil microbe and soil properties. However, the effect of G. lucidum cultivation on related wood segments, soil and tree roots microbial communities and soil properties is remain unknown. In our study, the microbial communities of soils, wood segments, and tree roots before and after G. lucidum cultivation were investigated by Illumina Miseq sequencing of both ITS and 16S rDNA, and taxonomic composition of eukaryotic and prokaryotic microorganisms were observed. Indices of microbial richness, diversity and evenness significantly differed between before and after G. lucidum cultivation. Each of the investigated sampling type harbored a distinctive microbial community and differed remarkably before and after G. lucidum cultivation. Ascomycota and Basidiomycota (fungi), Proteobacteria and Actinobacteria (bacteria) showed significant differences after Ling Zhi cultivation. The soil property values also changed after cultivation. The redundancy analysis (RDA) showed that both the fungal and bacterial community structure significantly correlated with soil humus, pH, nitrogen, carbon and trace elements (Fe, Zn, Mn, Cu) contents. The results indicated that G. lucidum cultivation may have significant differed the associated microbial community structures and soil properties. The study will provide useful information for G. lucidum cultivation and under-forest economic development.

Mucilaginibacter gilvus sp. nov., isolated from Antarctic soil

A Gram-stain-negative, aerobic, non-motile, rod-shaped, cold-tolerant bacterium, designated F01003^T, was isolated from soil sampled near Happiness Bay on the west coast of Antarctica. Strain F01003^T was found to grow at 4-30 °C (optimum, 25 °C), pH 5.5-8.0 (pH 6.5-7.0) and in the presence of 0-1 % NaCl (0 %, w/v). Cells were oxidase-positive and catalase-positive. Strain F01003^T contained menaquinone 7 (MK-7) as the predominant respiratory quinone. The main cellular fatty acids included summed feature 3 (C_16 : 1ω6c and/or C_16 : 1ω7c) and iso-C_15 : 0. Phosphatidylethanolamine and an unidentified aminolipid were identified as the major polar lipids. The DNA G+C content of strain F01003^T was 44.8 mol%. Phylogenetic analysis of the nearly full-length 16S rRNA gene sequence revealed that strain F01003^T was most closely related to the genus Mucilaginibacter and exhibited the highest sequence similarity to Mucilaginibacter phyllosphaerae LMG 29118^T (97.3 %). On the basis of the evidence presented in this polyphasic taxonomic study, strain F01003^T is considered to represent a novel species of the genus Mucilaginibacter, for which the name Mucilaginibactergilvus sp. nov. is proposed. The type strain is F01003^T (=KCTC 62991^T=CCTCC AB 2019023^T).