The Heavy-Metal Resistance Determinant of Newly Isolated Bacterium from a Nickel-Contaminated Soil in Southwest Slovakia

Abstract

A bacterial isolate MR-CH-I2 [KC809939] isolated from soil contaminated mainly by high nickel concentrations in southwest Slovakia was previously found carrying nccA-like heavy-metal resistance determinant, marked as MR-CH-I2-HMR [KF218096]. According to phylogenetic analysis of short (696 bp) 16S rDNA (16S rRNA) sequences this bacterium was tentatively assigned to Uncultured beta proteobacterium clone GC0AA7ZA05PP1 [JQ913301]. nccA-like gene product was on the same base of its partial (581 bp) sequences tentatively assigned to CzcA family heavy metal efflux pump [YP_001899332] from Ralstonia picketii 12J with 99% similarity. In this study the bacterium MR-CH-I2 and its heavy-metal resistance determinant were more precisely identified. This bacterial isolate was on the base of phylogenetic analysis of almost the whole (1,500 bp) 16S rDNA (16S rRNA) sequence, MR-CH-I2 [MF102046], and sequence for gyrB gene and its product respectively, MR-CH-I2-gyrB [MF134666], assigned to R. picketii 12J [CP001068] with 99 and 100% similarities, respectively. In addition, the whole nccA-like heavy-metal resistance gene sequence (3,192 bp), marked as MR-CH-I2-nccA [KR476581], was obtained and on the base of phylogenetic analysis its assignment was confirmed to MULTISPECIES: cation efflux system protein CzcA [WP_004635342] from Burkholderiaceae with 98% similarity. Furthermore, although the bacterium carried one high molecular plasmid of about 50 kb in size, nccA-like gene was not located on this plasmid. Finally, the results from RT-PCR analysis showed that MR-CH-I2-nccA gene was significantly induced only by the addition of nickel.

Keywords

• 16S rRNA (16S rDNA)
• DNA gyrase subunit B
• heavy-metal resistance determinant
• high molecular plasmid
• nickel-contaminated soil
• RT-qPCR