Neorhizobium tomejilense sp. nov., first non-symbiotic Neorhizobium species isolated from a dryland agricultural soil in southern Spain

International Committee on Systematics of Prokaryotes, Subcommittee on the taxonomy of Rhizobia and Agrobacteria, minutes of the annual meeting by videoconference, 5 July 2021, followed by online discussion until 31 December 2021

Minutes of the closed meeting of the International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Rhizobia and Agrobacteria held by videoconference, 5 July 2021, followed by online discussion until 31 December 2021, and list of recent species.

Neorhizobium xiangyangii sp. nov., isolated from a highland barley cultivation soil in Qamdo, Tibet

A novel Gram-negative, aerobic, rod-shaped and non-nitrogen fixing bacterium named T786^T was isolated from a highland barley cultivation soil in Qamdo, Tibet Autonomous Region, PR China. Strain T786^T grew at 5-30 ℃ and pH 6.0-10.0 (optimum, 20-25 ℃ and pH 7.0-8.0) with 0-4% (w/v) NaCl (optimum, 0%). The 16S rRNA gene sequences of strain T786^T showed the highest similarity to Neorhizobium vignae CCBAU 05176^T (98.7%), followed by Neorhizobium alkalisoli CCBAU 01393^T (98.5%), Neorhizobium tomejilense T17_20^T (98.4%), Neorhizobium huautlense S02^T (98.4%), and Neorhizobium galegae ATCC 43677^T (98.0%). Phylogenetic analysis based on 16S rRNA genes indicated that strain T786^T was a new member of the genus Neorhizobium. The digital DNA-DNA hybridization and average nucleotide identity values between strain T786^T and related strains were estimated as 20.2-20.6% and 76.6-80.0%, respectively. The genomic DNA G + C content based on the draft genome sequence was 60.2%. The major cellular fatty acids were Summed feature 8 (C_18:1 ω7c or C_18:1 ω6c), C_16:0 and Summed feature 3 (C_16:1 ω7c or C_16:1 ω6c). The polar lipids were diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl methyl ethanolamine, unidentified phospholipid and unidentified lipids (1-4). The isoprenoid quinone was ubiquinone-10. The DAP and sugar components of cell wall were meso-DAP and ribose, glucose, respectively. Based on phenotypic, phylogenetic, and genotypic data, for which the name Neorhizobium xiangyangii sp. nov. is proposed. The type strain is T786^T (= JCM 35100^T = CICC 25102^T).

Diversity of Culturable Bacteria Isolated from Highland Barley Cultivation Soil in Qamdo, Tibet Autonomous Region

The soil bacterial communities have been widely investigated. However, there has been little study of the bacteria in Qinghai-Tibet Plateau, especially about the culturable bacteria in highland barley cultivation soil. Here, a total of 830 individual strains were obtained at 4°C and 25°C from a highland barley cultivation soil in Qamdo, Tibet Autonomous Region, using fifteen kinds of media. Seventy-seven species were obtained, which belonged to 42 genera and four phyla; the predominant phylum was Actinobacteria (68.82%), followed by Proteobacteria (15.59%), Firmicutes (14.29%), and Bacteroidetes (1.30%). The predominant genus was Streptomyces (22.08%, 17 species), followed by Bacillus (6.49%, five species), Micromonospora (5.19%, four species), Microbacterium (5.19%, four species), and Kribbella (3.90%, three species). The most diverse isolates belonged to a high G+C Gram-positive group; in particular, the Streptomyces genus is a dominant genus in the high G+C Gram-positive group. There were 62 species and 33 genera bacteria isolated at 25°C (80.52%), 23 species, and 18 genera bacteria isolated at 4°C (29.87%). Meanwhile, only eight species and six genera bacteria could be isolated at 25°C and 4°C. Of the 77 species, six isolates related to six genera might be novel taxa. The results showed abundant bacterial species diversity in the soil sample from the Qamdo, Tibet Autonomous Region.

Synergistic effect of Klebsiella sp. FH-1 and Arthrobacter sp. NJ-1 on the growth of the microbiota in the black soil of Northeast China

The application of Atrazine in soil has always been a main problem in agriculture because its residuals may maintain in the soil for a long term. In this paper, two strains of Atrazine degrading bacteria (Klebsiella sp. FH-1 and Arthrobacter sp. NJ-1) were used to make biological compound microbial inoculum to repair the Atrazine contaminated typical black soil in Northeast China. Grain chaff was chosen as the optimal carrier material for microbial inoculum. The dynamic changes of Atrazine were detected by gas chromatography. The half-life of Atrazine in soil containing microbial inoculum was shortened from 9.8 d to 4.2 d. The Atrazine sensitive crops grown in the repaired soil showed increased stem length, root length, and emergence rate. The effects of microbial remediation on the original bacterial and fungal biota in the typical black soil in Northeast China were analyzed using the metagenomic approach. Results showed that Atrazine inhibited the original bacteria and fungi populations. The total numbers of bacterial and fungal species in the soil were partially recovered by adding the microbial inoculum. Two genera (Sphingosinicella and Sphingomonas) were the dominant bacteria. The beneficial bacterial biota was recovered and the number of species of the beneficial bacteria was higher than that in the original soil after adding the microbial inoculum. The dominant fungi included genera Guehomyces and Chaetomella. There was a total of 113 unclassified fungal genera (22.6% of 499), indicating the potential utility of the unclassified fungal species in the assessment of the soil contamination by Atrazine.

Neorhizobium lilium sp. nov., an endophytic bacterium isolated from Lilium pumilum bulbs in Hebei province

A novel gram-negative, aerobic, non-spore-forming, rod-shaped and non-nitrogen fixing bacterium named strain 24NR^T was isolated from wild Lilium pumilum bulbs in Fuping, Baoding City, Hebei province, PR China. The 16S rRNA gene sequences of strains 24NR^T showed the highest similarity to Neorhizobium alkalisoli DSM 21826^T (98.5%) and N. galegae HAMBI 540^T (98.1%). Phylogenetic analysis based on 16S rRNA genes and multilocus sequence analysis (MLSA) based on the partial sequences of atpD-glnII-glnA-recA-ropD-thrC housekeeping genes both indicated that strain 24NR^T is a member of the genus Neorhizobium. The average nucleotide identity between the genome sequence of strain 24NR^T and that of the isolate N. alkalisoli DSM 21826^T was 83.1%, and the digital DNA-DNA hybridization was 20.1%. The G+C content of strain 24NR^T was 60.3 mol %. The major cellular fatty acids were summed feature 8 (C_18:1ω7c and/or C_18:1ω6c) and C_19:0 cyclo ω8c. Based on phenotypic, phylogenetic, and genotypic data, strain 24NR^T is considered to represent a novel species of the genus Neorhizobium, for which the name Neorhizobium lilium sp. nov. is proposed. The type strain is 24NR^T (= ACCC 61588^T = JCM 33731^T).