Identification and Characterization of a Manganese-resistant Bacilli Isolate from Soil

Abstract:

A bacilli-shaped isolate with a unique dual manganese (II)-resistant and manganese (II)-oxidizing activities was screened from the yellow brown soil samples that collected in Queyu, Shandong Province, China. It exhibited a maximum manganese-resistant activity by 130 mmol/L of Mn (II), and a maximum manganese-oxidizing activity by 3.3 μmol/(L·d). This isolated was identified as a Bacillus megaterium strain (named as MB283) according to the morphological, physiological and biochemical characteristics, G + C content as well as the 16S rDNA sequence alignment analyses. Interestingly, the cell growth of MB283 was favored by the low concentration Mn (II) (10 mmol/L). A plasmid-cured mutant strain named as MB287 was obtained by perseveringly incubation of the strain at 43°C and supplementing additionally with 0.01% SDS. It was found that this mutant strain exhibited the proximate Mn (II)-resistant and Mn (II)-oxidizing activities compared to its wild-type strain. Thus, the results indicated that the corresponding genes of manganese resistance/oxidation in MB283 could locate in its chromosomal DNA.

Key words:Manganese resistance, Bacillus megaterium, Manganese oxidation, Identification, Plasmid curing