INVESTIGATION OF PROBIOTIC POTENTIAL OF BACILLUS SPP. ISOLATED FROM THE SOIL AND DIGESTIVE TRACT OF FISH


Kahraman B., Arıcı M. , Şenol B. M. , Dertli E.

III. International Agricultural, Biological & Life Science Conference, Edirne, Turkey, 1 - 03 September 2021, pp.366

  • Publication Type: Conference Paper / Summary Text
  • City: Edirne
  • Country: Turkey
  • Page Numbers: pp.366

Abstract

Bacillus species are gram-positive, aerobic, rod-shaped and endospore-forming organisms. An important group among Bacillus species is probiotics (e.g B. subtilis and B.clausii) which have beneficial effects on health. Especially in extreme environmental conditions, spores produced as a long-term survival tool have enabled the evaluation of Bacillus as probiotics. The aim of this study is to identify Bacillus species isolated from various sources to determine their properties and to evaluate their probiotic properties. For this purpose, firstly, Polymerase chain reaction (PCR) test was applied to Bacillus isolates and identification process was carried out through 16S rRNA genes. To determine the technological properties of isolates belonging to the genus Bacillus, their growth at different temperatures, different salt concentrations and different pH degrees were examined, and esculin hydrolysis, starch hydrolysis, nitrate reduction, gas formation from glucose tests were also carried out. For the probiotic potential of Bacillus isolates; in vitro tests such as bile tolerance, cell surface hydrophobicity assay, antibiotic susceptibility test, hemolysis and lecithinase detection were conducted. The findings showed that various Bacillus species isolated showed good growth at 30 and 40°C. Growth at 10% salt concentration also showed that these species can tolerate high salt concentrations. The isolates showed the best growth between pH 6 and pH 8. It was found that the isolates do not produce gas from glucose but all the bacterial strains could hydrolyze esculin and starch and utilize catalase. While all B. subtilis isolates were able to reduce nitrate, B. coagulans isolates were generally unable to reduce nitrate to nitrite. It is observed that the best developments in bile salts of Bacillus strains are in media containing 0.3% and 0.5% bile salts. Although the antibiotic susceptibility of the obtained isolates varies according to the types, when examined in general, it was observed that the strains were found to be susceptible and they were more sensitive especially to tetracycline and amoxicillin.