Paenibacillus lycopersici sp. nov. and Paenibacillus rhizovicinus sp. nov., isolated from the rhizosphere of tomato (Solanum lycopersicum)

Paenibacillus vietnamensis sp. nov., isolated from the rhizosphere soil of Arachis hypogaea

A novel bacterial strain, N4T, was isolated from the soil of a groundnut Arachis hypogaea field in Nghean province, Vietnam. The phylogenetic, chemotaxonomic and phenotypic characteristics of this strain were determined. Cells of strain N4T were Gram-negative, aerobic, endospore-forming and rod-shaped. Strain N4T grew at 20–37 °C (optimum, 30 °C), pH 6–10 (optimum, pH 7) and 0–5 % NaCl (optimum, 0 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N4T belonged to the genus Paenibacillus and was closely related to Paenibacillus harenae B519T (=KCTC 3951T) and Paenibacillus alkaliterrae KSL-134T (=KCTC 3956T) with 96.3 and 96.5% gene sequence similarity, respectively. It contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The DNA G+C content was 52.9 mol%. The major isoprenoid quinone was MK-7. Anteiso-C15 : 0 and iso-C16 : 0 were the dominant cellular fatty acids. Based on phylogenetic, physiological and biochemical characteristics, strain N4T represents a novel species of the genus Paenibacillus , for which the name Paenibacillus vietnamensis sp. nov. is proposed. The type strain is N4T (=KCTC 33932T= VTCC 12236T).

Description and genomic characterization of Jiella flava sp. nov., isolated from Acrostichum aureum

Two endophytic bacteria, designated strains CQZ9-1T and MQZ9-1, were isolated from semi-mangrove plant Acrostichum aureum collected from Maowei Sea Mangrove Nature Reserve in Guangxi Zhuang Autonomous Region, PR China. The two strains possessed almost identical 16S rRNA gene sequences (99.7 %). The average nucleotide identity (ANI), average amino acid identity (AAI) and the digital DNA-DNA hybridization (dDDH) values between the two strains were 100 %, indicating that they represented the same species. The 16S rRNA gene sequence similarities between strains CQZ9-1T, MQZ9-1 and the most closely related type strains, Jiella mangrovi KSK16Y-1T, Jiella sonneratiae MQZ13P-4T and Jiella endophytica CBS 5Q-3T were 98.0–98.1, 97.3–97.4 and 97.3–97.4 %, respectively. The results of phylogenetic analyses based on 16S rRNA gene sequences and genome sequences indicated that CQZ9-1T and MQZ9-1 formed a distinct lineage with J. endophytica CBS5Q-3T, Jiella pacifica 40Bstr34T, J. mangrovi KSK16Y-1T, J. sonneratiae MQZ13P-4T, Jiella aquimaris JCM 30119T and J. aquimaris 22II-16-19i. The draft genomes of strains CQZ9-1T and MQZ9-1 were 4  162  933 bp and 4  164  266 bp in size, respectively, and their DNA G+C contents were both 63.8 %. Comparative genome analysis of the two strains and the type strains of related species revealed ANI, AAI and dDDH values below the cut-off levels of 95-96, 95.5 and 70 %, respectively. The ubiquinone detected in CQZ9-1T was Q-10. The major cellular fatty acid of strains CQZ9-1T and MQZ9-1 was found to be C18:1ω7c. Combined data from phenotypic, phylogenetic and chemotaxonomic studies indicated that CQZ9-1T and MQZ9-1 represent a novel species of the genus Jiella , for which the name Jiella flava sp. nov. is proposed. The type strain is CQZ9-1T (= CGMCC 1.18725T = JCM 34331T).

Jiella sonneratiae sp. nov., a novel endophytic bacterium isolated from bark of Sonneratia apetala

A new endophytic bacterium, designated strain MQZ13P-4T was isolated from Sonneratia apetala collected from Maowei sea Mangrove Nature Reserve in Guangxi Zhuang Autonomous Region, PR China. The 16S rRNA gene sequence similarity between strain MQZ13P-4T and its closest phylogenetic neighbour Jiella endophytica CBS5Q-3T was 97.9 %. Phylogenetic analyses using 16S rRNA gene sequences and whole-genome sequences showed that strain MQZ13P-4T formed a distinct lineage with Jiella endophytica CBS5Q-3T, Jiella pacifica 40Bstr34T and Jiella aquimaris JCM 30119T. The draft genome of strain MQZ13P-4T was 5 153 243 bp in size and its DNA G+C content was 68.1 mol%. Comparative genome analysis revealed that the average nucleotide identity, digital DNA–DNA hybridization and average amino acid identity values among strain MQZ13P-4T and other related species were below the cut-off levels of 95, 70 and 95.5 %, respectively. The cell-wall peptidoglycan of strain MQZ13P-4T contained meso-diaminopimelic acid as the diagnostic diamino acid. The respiratory quinone was Q-10. The major cellular fatty acid was C18 : 1  ω7c. The polar lipids comprised phosphatidylcholine, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified aminolipids and two unidentified lipids. Strain MQZ13P-4T had a typical chemical compositions of fatty acids, lipids, quinones and diagnostic diamino acid for Jiella species, but could be distinguished from known species of the genus Jiella . Based on polyphasic evidence, strain MQZ13P-4T represents novel species of the genus Jiella , for which the name Jiella sonneratiae sp. nov. is proposed. The type strain is MQZ13P-4T (=CGMCC 1.18727T=JCM 34333T).

Effect of exopolysaccharides of Paenibacillus polymyxa rhizobacteria on physiological and morphological variables of wheat seedlings

Paenibacillus polymyxa is a promising plant-growth-promoting rhizobacterium that associates with a wide range of host plants, including agronomically important ones. Inoculation of wheat seedlings with P. polymyxa strains CCM 1465 and 92 was found to increase the mitotic index of the root cells 1.2- and 1.6-fold, respectively. Treatment of seedlings with the exopolysaccharides (EPSs) of these strains increased the mitotic index 1.9-fold (P. polymyxa CCM 1465) and 2.8-fold (P. polymyxa 92). These increases indicate activation of cell division in the root meristems. Analysis of the morphometric variables of the seedlings showed that P. polymyxa CCM 1465, P. polymyxa 92, and their EPSs promoted wheat growth, increasing root and shoot length up to 22% and root and shoot dry weight up to 28%, as compared with the control. In addition, both strains were found to intensely colonize the seedling root surface. Thus, P. polymyxa EPSs are active metabolites that, along with whole cells, are responsible for the contact interactions of the bacteria with wheat roots and are implicated in the induction of plant responses to these interactions. The strains used in this work are of interest for further study to broaden the existing understanding of the mechanisms of plant-bacterial interactions and to develop effective biofertilizers for agricultural purposes.