Draft genome sequence of Mycobacterium rufum JS14(T), a polycyclic-aromatic-hydrocarbon-degrading bacterium from petroleum-contaminated soil in Hawaii

Integrated approach of whole-genome analysis, toxicological evaluation and life cycle assessment for pyrene biodegradation by a psychrophilic strain, Shewanella sp. ISTPL2

Polycyclic aromatic hydrocarbons (PAHs) such as pyrene are universal contaminants existing in the environment which have known cancer-causing and mutagenic characteristics. A psychrophilic bacterial strain Shewanella sp. ISTPL2 was isolated from the sediment sample collected from the Pangong lake, Jammu & Kashmir, India. In our previous study, the pyrene degradation potential of the ISTPL2 strain was studied in both mineral salt media as well as in soil artificially spiked with different concentrations of pyrene. Whole-genome sequencing of ISTPL2 strain in the current study highlighted the key genes of pyrene metabolism, including alcohol dehydrogenase and ring hydroxylating dioxygenase alpha-subunit. Pyrene cytotoxicity was evaluated on HepG2, a human hepato-carcinoma cell line. The cytotoxicity of the organic extract decreased with the increasing duration of bacterial treatment. To develop a more sustainable biodegradation approach, the potential impacts were evaluated for human health and ecosystem using life-cycle assessment (LCA) following the ReCiPe methodology for the considered PAH. The results implemented that global warming potential (GWP) had the highest impact, whereas both ecotoxicity and human toxicity had least from this study.

Autochthonous Bioaugmentation-Modified Bacterial Diversity of Phenanthrene Degraders in PAH-Contaminated Wastewater as Revealed by DNA-Stable Isotope Probing

To reveal the mechanisms of autochthonous bioaugmentation (ABA) in wastewater contaminated with polycyclic aromatic hydrocarbons (PAHs), DNA-stable-isotope-probing (SIP) was used in the present study with the addition of an autochthonous microorganism Acinetobacter tandoii LJ-5. We found LJ-5 inoculum produced a significant increase in phenanthrene (PHE) mineralization, but LJ-5 surprisingly did not participate in indigenous PHE degradation from the SIP results. The improvement of PHE biodegradation was not explained by the engagement of LJ-5 but attributed to the remarkably altered diversity of PHE degraders. Of the major PHE degraders present in ambient wastewater ( Rhodoplanes sp., Mycobacterium sp., Xanthomonadaceae sp. and Enterobacteriaceae sp.), only Mycobacterium sp. and Enterobacteriaceae sp. remained functional in the presence of strain LJ-5, but five new taxa Bacillus, Paenibacillus, Ammoniphilus, Sporosarcina, and Hyphomicrobium were favored. Rhodoplanes, Ammoniphilus, Sporosarcina, and Hyphomicrobium were directly linked to, for the first time, indigenous PHE biodegradation. Sequences of functional PAH-RHD_α genes from heavy fractions further proved the change in PHE degraders by identifying distinct PAH-ring hydroxylating dioxygenases between ambient degradation and ABA. Our findings indicate a new mechanism of ABA, provide new insights into the diversity of PHE-degrading communities, and suggest ABA as a promising in situ bioremediation strategy for PAH-contaminated wastewater.

Larkinella terrae sp. nov., isolated from soil on Jeju Island, South Korea

A Gram-stain negative, non-motile, rod-shaped, aerobic bacterium, designated 15J8-8^T, was isolated from a soil sample collected on Jeju Island, South Korea, and characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain 15J8-8^T belongs to the family Cytophagaceae and is related to Larkinella bovis M2TB15^T (95.0%), 'Larkinella harenae' 15J9-9 (94.5%), Larkinella arboricola Z0532^T (93.2%), and Larkinella insperata LMG 22510^T (93.0%). The DNA G+C content of strain 15J8-8^T was 50.5 mol%. The detection of phosphatidylethanolamine and two unidentified polar lipids as major polar lipids; menaquinone-7 as the predominant quinone; and C_16:1 ω5c, C_16:0 N alcohol, and iso-C_15:0 as the major fatty acids also supported the affiliation of the isolate to the genus Larkinella. Based on its phenotypic properties and phylogenetic distinctiveness, strain 15J8-8^T should be classified in the genus Larkinella as representative of a novel species, for which the name Larkinella terrae sp. nov. is proposed. The type strain is 15J8-8^T (= KCTC 52001^T = JCM 31990^T).