Kun Zhang

Heterotrophic nitrification–aerobic denitrification (HN-AD) is an efficient nitrogen removal process and the genus Paracoccus is one important group of the HN-AD bacteria. During an investigation of the microbial diversity in marine ranching of the Pearl River Estuary (PR China), three bacterial strains, designated SCSIO 75817^T, SCSIO 76264^T and SCSIO 80058^T, were isolated from sediments. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the three strains belonged to the genus Paracoccus and their closest neighbors were P. isoporae DSM 22220^T (97.6–98.0%), P. aurantiacus CGMCC 1.13898^T (97.3–97.6%) and P. xiamenensis MCCC 1A16381^T (97.1–97.4%), respectively. The analysis results of 16S rRNA gene similarity, ANI, AAI and dDDH showed that the pairwise similarities between these three strains and their closest neighbors were 97.4–98.5%, 76.9–81.0%, 75.5–79.6% and 20.3–23.3%, respectively. Polyphasic taxonomic data of the phylogenetic, phenotypic and chemotaxonomic analyses indicate that these strains represent three novel species in the genus Paracoccus, for which the names Paracoccus aerodenitrificans sp. nov., Paracoccus sediminicola sp. nov. and Paracoccus albus sp. nov. are proposed, respectively. The study also demonstrated the heterotrophic nitrification–aerobic denitrification (HN-AD) ability of the novel species P. aerodenitrificans SCSIO 75817^T. When it was aerobically cultivated at 28 °C using NH₄⁺-N, NO₃⁻-N and NO₂⁻-N as the sole nitrogen sources, the nitrogen removal efficiencies were 73.4, 55.27 and 49.2%, respectively, and the maximum removal rates were 3.05, 1.82 and 1.63 mg/L/h, respectively. The results suggest that it has promising potential for wastewater treatment.

A Gram-stain-positive, non-motile, aerobic, rod-shaped, golden yellow-pigmented actinobacterium, designated strain YIM 123512^T, was isolated from soil sampled at Gaoligong Mountain, Yunnan Province, PR China. The strain grew at 10–40 °C (optimum, 28 °C), with 0–3.0 % (w/v) NaCl (optimum, 0–1.0 %) and at pH 5.0–11.0 (optimum, pH 7.0). The major menaquinone was MK-8(H₄) and the major cellular fatty acids (>10 %) were identified as iso-C_16 : 0 and C_17 : 1  ω8c. Strain YIM 123512^T had ll-2, 6-diaminopimelic acid as the diagnostic cell-wall diamino acid. The major polar lipids were found to be diphosphatidylglycerol, phosphatidylglycerol, two unknown phospholipids and one unknown lipid. The genomic DNA G+C content of strain YIM 123512^T was 72.7 mol% based on its draft genome sequence. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain YIM 123512^T appeared to be most closely related to Nocardioides halotolerans KCTC 19274^T (97.7 % sequence similarity) and to belong to the genus Nocardioides . The sequence similarity values of strain YIM 123512^T to other currently described type strains of the genus Nocardioides were less than 97.0 %. Based on the draft genome sequence, the novel strain showed an average nucleotide identity value of 80.2 % and a digital DNA–DNA hybridization value of 23.1 % with the reference strain N. halotolerans KCTC 19274^T. The results of the polyphasic taxonomic study including phenotypic, chemotaxonomic and phylogenetic analyses show that strain YIM 123512^T represents a novel species of the genus Nocardioides , for which the name Nocardioides flavescens sp. nov. is proposed. The type strain is YIM 123512^T (=KCTC 49303^T=CGMCC 4.7628^T).

A Gram-stain-positive, strictly aerobic, rod-shaped, motile, endospore-forming strain, SYSU K30001T, was isolated from a soil sample collected from a cave in Xingyi county, Guizhou province, south-west China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SYSU K30001T belonged to the genus Bacillus , with the highest sequence similarity to the type strain of Bacillus panaciterrae (98.1 %). Growth occurred at pH 6.0–9.0 (optimum, pH 7.0), at 28–55 °C (optimum, 28 °C) and in the presence of 0–3 % (w/v) NaCl (optimum in the absence of NaCl). Strain SYSU K30001T contained meso-2,6-diaminopimelic acid in the cell-wall peptidoglycan and MK-7 as the only isoprenoid quinone present. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified glycolipid. The major fatty acids were iso-C15 : 0, iso-C17 : 1 ω10c, anteiso-C14 : 0 and iso-C17 : 0. The genome G+C content was 39.8 mol%. The average nucleotide identity values between SYSU K30001T and B. panaciterrae DSM 19096T were 72.1 % (ANIb) and 83.1 % (ANIm), which were below the cut-off level (95–96 %) for species delineation. Based on phenotypic, chemotaxonomic and molecular characterizations, strain SYSU K30001T represents a novel species of the genus Bacillus , for which the name Bacillus antri sp. nov. is proposed. The type strain is SYSU K30001T (=KCTC 33954T=CGMCC 1.13871T).