Identification of arsenic oxidizing genes fragment in Microbacterium sp. strain 1S1 and its cloning in E. coli (DH5a)

Microbacterium sp. strain 1S1, an arsenic-resistant bacterial strain, was isolated with 75 mM MIC against arsenite. Brownish precipitation with silver nitrate appeared, which confirmed its oxidizing ability against arsenite. The bacterial genomic DNA underwent Illumina and Nanopore sequencing, revealing a distinctive cluster of genes spanning 9.6 kb associated with arsenite oxidation. These genes were identified within an isolated bacterial strain. Notably, the smaller subunit (aioB) of the arsenite oxidizing gene at the chromosomal DNA locus (Prokka_01508) was pinpointed. This gene, aioB, is pivotal in arsenite oxidation, a process crucial for energy metabolism. Upon thorough sequencing analysis, only a singular megaplasmid was detected within the isolated bacterial strain. Strikingly, this megaplasmid did not harbor any genes responsible for arsenic resistance or detoxification. This intriguingly indicates that the bacterial strain relies on the arsenic oxidizing genes present for its efficient arsenic oxidation capability. This is especially true for Microbacterium sp. strain 1S1. Subsequently, a segment of genes linked to arsenic resistance was successfully cloned into E. coli (DH5a). The fragment of arsenic-resistant genes was cloned in E. coli (DH5a), further confirmed by the AgNO3 method. This genetically engineered E. coli (DH5a) can decontaminate arsenic-contaminated sites.