[Effects of salinity on soil bacterial diversity and assembly processes in coastal soils.] / ç›åº¦å¯¹æ»¨æµ·åœŸå£¤ç»†èŒå¤šæ ·æ€§å’Œç¾¤è½æž„å»ºè¿‡ç¨‹çš„å½±å“.

Coastal saline soil is an important reserve resource of agricultural land. Soil microorganisms play a key role in soil nutrient cycling. However, it is still far from clear about the effects of salinity on soil microbial community. We examined the effects of salinity on soil bacterial abundance, diversity, and community assembly, by collecting soil samples in coastal areas with three salinity levels (non-, mild-, and severe-salinity). Our results showed that the activity of dehydrogenase and the abundance of bacteria significantly decreased in the severe-saline soils, while the diversity of bacteria remained unchanged, compared with non- and mild-saline soils. Bacterial communities were clustered by salinity. Null model was used to infer bacterial community assembly processes. Salinity was the main driving factor for bacterial community assembly. Deterministic process driven by salinity played a leading role in controlling bacterial community composition in coastal saline soil. These findings suggested that coastal saline soils contain abundant microbes within the salinity range, and have a biological basis for soil improvement. Due to the high deterministic process of microbial community assembly, it would be difficult for alien species to colonize coastal saline soils. Salt-tolerant and indigenous strains are recommended when using microbial technology to reclaim coastal saline soils.

Bacillus fengqiuensis sp. nov., isolated from a typical sandy loam soil under long-term fertilization.

A Gram-staining-positive, endospore-forming, moderately alkaliphilic bacterium, strain NPK15(T), was isolated from a typical sandy loam soil under long-term NPK fertilization in northern China and was subjected to a polyphasic taxonomic study. The diamino acid of the cell-wall peptidoglycan of strain NPK15(T) was found to be meso-diaminopimelic acid and the cell-wall sugars were xylose, glucose and traces of mannose. The only respiratory quinone found in strain NPK15(T) was menaquinone 7 (MK-7). The major cellular fatty acids were iso-C(15 : 0), anteiso-C(15 : 0), C(16 : 0) and C(16 : 1)ω6c/C(16 : 1)ω7c. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis of the strain based on its 16S rRNA gene sequence showed that it was related most closely to 'Bacillus thaonhiensis' KACC 17216 (99.59%), B. songklensis KCTC 13881(T) (99.52%) and B. abyssalis CCTCC AB 2012074(T) (99.00%). DNA-DNA hybridization results indicated that the strain was distinct from other species of the genus Bacillus, the degree of relatedness being 35.4% with B. abyssalis CCTCC AB 2012074(T), 39.7% with B. songklensis KCTC 13881(T) and 51.2% with 'B. thaonhiensis' KACC 17216. The DNA G+C content of strain NPK15(T) was 45.5 mol%. Phenotypic, chemotaxonomic and molecular analyses identified strain NPK15(T) as a member of a novel species of the genus Bacillus, for which the name Bacillus fengqiuensis sp. nov. is proposed. The type strain is NPK15(T) ( = DSM 26745(T) = CCTCC AB 2013156(T)).