Abstract
Identification of 33 Bacillus spp. isolates from different environmental samples collected from the territory of Serbia was performed by sequencing of the 5?-hypervariable section of 16S rRNA gene. Eight species were identified within four phylogenetic groups: B. pumilus, B. megaterium, B. subtilis and B. cereus. Determination of their antibiotic resistance was performed using the minimum inhibitory concentration (MIC) assay. We found that just one isolate was resistant to gentamicin, 9 were resistant to clindamycin and all were resistant to vancomycin. Based on the profile of resistance, the isolates were categorized into 4 categories. In silico analysis of the erythromycin-resistance (erm) gene for clindamycin resistance showed their distribution between related and nonrelated soil and human isolates including different species of Bacillus genera. This finding indicates that Bacillus spp. from the environment could be a source of resistance to clindamycin. The potential for the presence and spread of resistance determinants in the soil and similar ecosystems exists so that monitoring of antibiotic resistance genes in nonpathogenic Bacillus strains from the environment is advised.
Highlights
Nature in its widest sense is an abundant source of many different species of the genus Bacillus
This study was aimed at identifying a collection of 33 Bacillus spp. strains isolated from natural samples of soil, hay and manure by sequencing of the 5’ hypervariable segment of the 16S rRNA gene, testing identified strains for antibiotic resistance and in silico analysis of the genetic determinants of clindamycin resistance in order to examine whether they represent a reservoir of resistance in the natural environment
The BLAST database search revealed eight species with the following distribution: six isolates clustered with Bacillus pumilus, two with Bacillus megaterium, three with B. subtilis, ten with B. amyloliquefaciens, one with B. licheniformis, and three that were most similar to B. cereus, seven to B. thuringiensis and one to B. anthracis
Summary
Nature in its widest sense is an abundant source of many different species of the genus Bacillus. In various habitats associated with soil, in water, on and in plants, in special types of food, even in clinical specimens, Bacillus spp. can be found. Hallmarks of the genus are its rod-shape, endospore formation and predominantly Gram-positive aerobic bacteria. The golden standard in molecular identification of prokaryotes was analysis of the sequence of the gene for 16S rRNA [2,3]. Satisfactory resolution at species level for some Bacillus spp. can be achieved using universal primers for 16S rDNA, the majority of sequences could be gathered into phylogenetic groups at best [1]. Many species fall into several distinct phylogenetic groups, such as B. subtilis, B. cereus, B. pumilus and B. sphaericus that can be even phenotypically distinguishable, but issues
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
