No abstract

A novel yellow-pigmented, non-motile, non-sporulating, catalase- and oxidase-positive, obligately aerobic, moderately halophilic, facultatively alkaliphilic Gram-positive coccus, strain YIM Y15T, was isolated from a brine sample from a salt mine in Yunnan, south-west China. Strain YIM Y15T grew in the presence of 0.5–25 % (w/v) NaCl and at pH 6.0–10.0, with optimum growth at 8–10 % (w/v) NaCl and pH 8.0. It grew at 4–45 °C, with optimum growth at 37.0 °C. The major cellular fatty acids were anteiso-C15 : 0 and iso-C15 : 0. Menaquinone 6 (MK-6) was the major respiratory quinone. The cell wall contained Lys and Gly. The DNA G+C content was 46.2 mol%. Phylogenetic analyses based on 16S rRNA gene sequence comparisons revealed that strain YIM Y15T was a member of the genus Salinicoccus, with low 16S rRNA gene sequence similarity to the type strains of the five described species of the genus, Salinicoccus alkaliphilus JCM 11311T (sequence similarity 96.0 %), Salinicoccus roseus DSM 5351T (94.9 %), Salinicoccus jeotgali KCTC 13030T (94.8 %), Salinicoccus salsiraiae LMG 22840T (94.8 %) and Salinicoccus hispanicus DSM 5352T (94.7 %). Together with the phenotypic differences, these results supported the proposal of a novel species of the genus Salinicoccus, Salinicoccus kunmingensis sp. nov., with YIM Y15T (=DSM 17847T =CGMCC 1.6302T) as the type strain.

Growth and productivity of rice is negatively affected by soil salinity. However, some salt-tolerant bacteria improve the health of plants under saline stress. In this study, 305 bacteria were isolated from paddy soil in Taoyuan, China. Among these, 162 strains were tested for salt-tolerance; 67.3%, 28.4%, and 9.3% of the strains could grow in media with NaCl concentrations of 50, 100, and 150 g/L, respectively. The phylogenic analysis of 74 of these 162 strains indicates that these bacteria belong to Bacillales (72%), Actinomycetales (22%), Rhizobiales (1%), and Oceanospirillales (4%). Among 162 strains, 30 salt-tolerant strains were screened for their plant-growth-promoting activities under axenic conditions at 3, 6, 9, and 12 g/L NaCl; 43%-97% of the strains could improve rice germination energy or germination capacity, while 63%-87% of the strains could increase shoot and root lengths. Among various plant-growth-promoting bacteria, TY0307 was the most effective strain for promoting the growth of rice, even at high salt stress. Its promotor effects were associated with its production of 1-aminocyclopropane-1-carboxycarboxylate deaminase, indole acetic acid, and siderophores; induction of proline accumulation; and reduction of the salt-induced malondialdehyde content. These results suggest that several strains isolated from paddy soil could improve rice salt tolerance and may be used in the development of biofertilizer.

Microbes are thought to have key roles in the development of the special properties of post-fermented pu-erh tea (pu-erh shucha), a well-known traditional Chinese tea; however, little is known about the bacteria during the fermentation. In this work, the structure and dynamics of the bacterial community involved in the production of pu-erh shucha were investigated using 16S rRNA gene clone libraries constructed from samples collected on days zero (LD-0), 5 (LD-5), 10 (LD-10), 15 (LD-15) and 20 (LD-20) of the fermentation. A total of 747 sequences with individual clone library containing 115-174 sequences and 4-20 unique operational taxonomic units (OTUs) were obtained. These OTUs were grouped into four phyla (Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria) and further identified as members of 10 families, such as Alcaligenaceae, Bacillaceae, Enterobacteriaceae, etc. The dominant bacteria were Enterobacteriaceae in the raw material (LD-0) and in the initial stages of fermentation (LD-5 and LD-10), which changed to Bacillaceae at the last stages of fermentation (LD-15 and LD-20) at a temperature of 40-60 °C. It is interesting that the dominant OTUs in libraries LD-15 and LD-20 were very closely related to Bacillus coagulans, which is a safe thermoduric probiotic. Together the bacterial diversity and dynamics during a fermentation of pu-erh shucha were demonstrated, and a worthy clue for artificial inoculation of B. coagulans to improve the health benefits of pu-erh shucha or produce probiotic pu-erh tea were provided.

A catalase-negative actinomycete, strain YIM 21741 T , was isolated from a soil sample collected from a primeval forest at Xishuangbanna, Yunnan Province, China. Analysis of 16S rDNA showed the strain to be related to members of the genus Agromyces, with which it also shares morphological characteristics, e.g. branching hyphae breaking into diphtheroid and rod-like, irregular, non-motile fragments and a peptidoglycan containing the diagnostic amino acid 2,4-diamino-n-butyric acid. Whole-cell hydrolysates of strain YIM 21741T contained rhamnose and small quantities of glucose, galactose and mannose.