北戴河海洋沉积物中L-半胱氨酸脱硫细菌的多样性及其特性

Diversity and characterization of L-cysteine desulfurizing bacteria isolated from marine sediments in Beidaihe

摘要:

【背景】脱硫细菌对有机硫的脱硫作用在硫的生物地球化学循环以及脱硫工业中都起着重要的作用。【目的】了解海洋沉积物中可分解有机物产生硫化氢的细菌多样性。【方法】对我国北戴河海洋沉积物中可培养的L-半胱氨酸脱硫细菌进行分离与筛选，通过对其16S rRNA基因序列测定与分析，构建系统发育树，并对其脱硫、脱氮能力进行检验。【结果】从海洋沉积物中分离得到97株细菌，从以L-半胱氨酸为硫源的培养基中筛选出62株有机脱硫专一型细菌。根据脱硫细菌的形态及其特征，从中选取12株作为典型代表做进一步分析，它们分别属于芽孢杆菌属(Bacillus)、赖氨酸芽孢杆菌属(Lysinibacillus)、动性球菌属(Planococcus)和红球菌属(Rhodococcus)。结果表明，这12株细菌均可产生半胱氨酸脱巯基酶，能够将半胱氨酸分解为丙酮酸、硫化氢和氨，即同时具备脱硫与脱氮的能力。其中有5株菌脱硫能力较强，分别属于赖氨酸芽孢杆菌属、动性球菌属和芽孢杆菌属。【结论】海洋沉积物中存在着丰富的L-半胱氨酸脱硫细菌，为进一步研究海洋中硫的生物地球化学循环提供了素材。

Abstract:

[Background] Organic sulfur desulfurization catalyzed by desulfurizing bacteria plays an important role in the biogeochemical cycle of sulfur and the desulfurization industry. [Objectives] In order to investigate the diversity of bacteria using the organic sulfur to produce hydrogen sulfide in marine sediments, this research focused on the isolation and characterization of desulfurizing bacteria. [Methods] The culturable desulfurizing bacteria were isolated from the marine sediments sampled from Beidaihe, which were subjected to the screening by the media containing both lead acetate and L-cysteine. Then, the 16S rRNA gene sequences of desulfurizing bacteria were retrieved against the GenBank database. All of the gene sequences with the reference sequences were used to construct the phylogenetic tree. Finally, the bacteria were tested for their capabilities for desulfurization and denitrification. [Results] 62 desulfurizing bacteria were screened out from a total of 97 bacterial strains, out of which, 12 desulfurizing bacteria were selected as the representatives to subject to phylogenetic analysis based on their 16S rRAN gene sequences. The results indicated that all the bacterial strains belong to the genus of Bacillus, Lysinibacillus, Planococcus and Rhodococcus, respectively. Five strains with strong desulfurization ability were affiliated to three genus of Lysinibacillus, Planococcus and Bacillus. Further test showed that the desulfurizing bacteria can produce cysteine desulfhydrase to catalyze the conversion of L-cysteine to pyruvate, hydrogen sulfide and ammonia, indicating they possess both of the capabilities of desulfurization and denitrification. [Conclusion] There are abundant L-cysteine desulfurization bacteria in marine sediments, which provide materials for further study of biogeochemical cycle of sulfur in the ocean.