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

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.