Isolation and taxonomic analysis of Bacillus species in Anthrax negative cases at Central Veterinary Laboratory, Namibia
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Date
2021
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Publisher
University of Namibia
Abstract
The emergence of anthrax-like infections caused by Bacillus spp. other than Bacillus anthracis is quickly becoming a topical issue. This brought more concern to the scientific community, guardians of public health, and veterinarians around the world. Some bacillus species that cause anthrax-like infections harbor plasmids similar to those in Bacillus anthracis that encode for toxin genes while in some cases anthrax-like etiologic agents have not been investigated for virulence genes. In some instances, however, anthrax-like etiologic agents harbor virulence genes different from those of B. anthracis yet still cause anthrax-like infections. The present study aimed to isolate bacillus species from anthraxnegative samples and analyses the possibility of isolates to cause anthrax-like infections. The samples used were obtained from the Central Veterinary Laboratory (CVL) in Windhoek, Namibia. The samples analyzed in the study were submitted to CVL over the
period of May 2019 to March 2020 for B. anthracis test, but they tested negative. Twentythree (23) samples were obtained and analyzed for the presence of Bacillus spp. by culture methods. This was followed by DNA extraction and then amplification of the 16S rDNA gene using universal 16S bacterial primer sets 27F and 1492R. From the 23 original samples, 13 different Bacillus spp. were identified by BLAST search on NCBI. The identified species were Bacillus australimaris, Bacillus pumilus, Bacillus subtilis, Bacillus simplex, Bacillus megaterium, Bacillus licheniformis, Bacillus albus, Bacillus aryabhattai, Bacillus acanthi, Bacillus thuringiensis, Bacillus cereus, Bacillus zhangzhouensis and Bacillus safensis. Due to COVID-19 related complication, the isolated bacillus species could not be tested for the presence of virulence genes. However, statistical determinations were carried out to determine if there were correlations between the isolated strains and the symptoms presented by the animals from which the samples were obtained. The chi square value is 0.104 which is greater than the significant value (p=0.05). Of the isolated bacillus species B. cereus, B. pimulus, and B. megaterium where once isolated from anthrax-like infection. This study isolated bacillus species from anthrax negative samples that may not be responsible for anthrax-like infections based on the statistical analysis. However, screening of virulence genes in further studies is recommendable to prove this conclusion.
Description
A mini thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science (Microbiology)
Keywords
Anthrax-like infections, Anthrax-like isolates, Bacillus species