青藏高原北部湖泊沉积物中基于不同碳源可培养细菌多样性

Diversity of Cultivable Bacteria Based on Different Carbon Sources in the Sediments of Lakes on Northern Qinghai-Tibet Plateau

中文关键词:  青藏高原湖泊  沉积物  可培养细菌  碳源利用  多样性  盐度

英文关键词::Qinghai-Tibet Plateau lakes  Sediments  Cultivable bacteria  Carbon substrates utilization  Diversity  Salinity

中文摘要:

      前人研究显示微生物群落对有机碳源的利用具有选择性,但是纯菌株对碳源利用的选择性却不甚明了。此外,在盐湖环境中微生物出于能量的考虑可能选择性利用有机碳源以抵抗盐度渗透压。因此,盐度可能间接地影响微生物对有机碳源的利用。然而,目前类似的相关研究较少。采用单碳源纯培养技术、16S rRNA基因序列分析和相关统计方法,研究了青藏高原北部6个湖泊(洱海、青海湖、托素湖、尕海1、尕海2、小柴旦湖)沉积物中基于不同碳源可培养细菌多样性及其与盐度的响应关系。采用7种不同类型的单碳源(甲酸钠、乙酸钠、丙酮酸钠、乳酸钠、葡萄糖、纤维素、混合氨基酸)进行培养筛选。共获得10个细菌分类属的75株纯培养菌株,它们分属于γ-变形菌纲的气单胞菌属(Aeromonas)、盐单胞菌属(Halomonas)、希瓦氏菌属(Shewanella)、假单胞菌属(Pseudomonas)、假交替单胞菌属(Pseudoalteromonas)、弧菌属(Vibrio),β-变形菌纲的脱氯单胞菌属(Dechloromonas)以及芽孢杆菌纲的芽孢杆菌属(Bacillus)、微小杆菌属(Exiguobacterium)和游动球菌属(Planococcus)。其中,盐单胞菌属菌株可利用研究中使用的所有碳源类型,说明这类细菌具有广泛碳代谢途径,可能潜在参与了青藏高原北部湖泊碳循环过程。研究发现所得纯菌株对不同碳链长度碳源的利用具有选择性,即随着盐度增高,某些菌株偏向利用结构更加复杂的碳源。总之,盐度不仅影响着纯培养细菌群落多样性,而且还影响着细菌对碳源类型的选择。

英文摘要:

      :Bacterial community structure was influenced by the composition of dissolved organic carbon (DOC), selective utilization of distinct carbon substrates can be observed for different bacterial taxa. However, selective utilization of distinct carbon substrates on pure strains and its response to salinity are still rare. Here, we investigated the diversity of cultivable bacteria and their response to salinity and carbon substrates in sediments from six lakes (Erhai Lake, Qinghai Lake, Tuosu Lake, Gahai Lake 1, Gahai Lake 2, Xiaochaidan Lake, salinity range from 1 to 72 g/L) in northern Qinghai-Tibet Plateau by using single carbon substrate cultivation and polymerase chain reaction-based phylogenetic analyses. Seven carbon substrates (e.g.sodium formate, sodium acetate, sodium pyruvate, sodium lactate, glucose, cellulose and amino acids mixture) were used for enrichment cultivation. The obtained bacterial strains are affiliated with ten bacterial genera, e.g. Pseudomonas, Aeromonas, Shewanella, Dechloromonas, Planococcus, Halomonas, Exiguobacterium, Vibrio, Pseudoalteromonas and Bacillus. The strains within Halomonas can utilize all the seven tested carbon substrates, indicating that they possess extensive carbon metabolic pathways and are of capable of mediating carbon cycling in the studied lakes. The obtained bacterial strains employ carbon sources of different carbon length differently as salinity increases:certain bacterial strains prefer more complex carbon sources in response to salinity increase. In summary, salinity not only affects the cultivable bacterial diversity but also utilization of carbon substrates in the sediments of lakes in northern Qinghai-Tibet Plateau.