盐度对滨海土壤细菌多样性和群落构建过程的影响

Effects of salinity on soil bacterial diversity and assembly processes in coastal soils

滨海盐土是重要的农业土地后备资源。微生物是土壤中物质循环的关键动力,然而盐度对土壤微生物群落特征影响的研究还很缺乏。本研究采集滨海地区的土壤样品,研究非盐、轻盐和高盐3组不同盐度对土壤细菌数量、多样性和群落构建的影响。结果表明:与非盐和轻盐土壤相比,高盐土壤的脱氢酶活性和细菌数量显著降低,而细菌α多样性没有变化,细菌群落结构发生分异。利用零模型反演群落构建过程,发现盐度是细菌群落构建过程的主控因子,盐度主导的高确定性过程控制了滨海盐土细菌的群落结构。说明在现有的盐度范围内,高盐土壤中同样含有丰富的微生物种质资源,具有盐土改良的生物学基础,然而由于高确定性的群落构建机制,外源物种很难定殖于滨海盐土。因此,在利用微生物技术改良滨海盐土时,应尽可能筛选耐盐的土著菌种,提高定殖效率。

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.