Abstract:
Bacteria are the oldest, structurally simplest and the most abundant form of life on earth. They infect a wide range of organisms including plants, animals and invertebrates. Spices constitute an important group of agriculture commodities and they are not free from microbial association like fungi, bacteria and viruses. They may acquire microorganisms during growth and development or during postharvest stages like collection, processing, storage and marketing. The present work was aimed to identify different types of bacteria associated with common spices to understand their physiological characteristics and to find out the potential probiotic Bacillus strains. Total 65 isolates were isolated from spices; only ten strains were characterized by using biochemical tests and molecular techniques. Eight selected strains were accessed for tolerance to acidic pH, high osmotic concentrations of NaCl and different concentrations of bile salts, as a pre-requisite for potential probiotic candidate. Theses isolates were subjected to pH of 2.0 and 3.0, NaCl concentration of 3.5 and 6.5 percent and bile salts concentration of 0.037, 0.15, 0.3 percent with nutrient broth at 37°C. A varied tolerance capacity for acid, NaCl and bile was observed for these isolates. Bacterial strains were identified by sequencing using 16s rRNA primers. Phylogenetic analysis was conducted using Geneious software. Among the tested strains, one strain KY986416 showed high level of tolerance at pH 2 and 3, different bile concentrations and this strain was found susceptible to all 4 antibiotics CN-10 (Gentamicin), AMC-30 (Amoxycillin), TE-30 (tetracycline) and PB-300 (Polymyxin) tested for safety assessment of antibiotic resistance gene. It is confirmed by biochemical and molecular identification that bacteria associated with spices are mostly from Genus Bacillus. Total 12 different bacterial species have been identified through sequencing in this study and their data is submitted in the Genbank. Few of the tested Bacillus species are showing tolerance towards the acidic conditions and different salt concentrations so they might have potential to be used as probiotic candidates. They can be further analyzed by using in-vivo studies.
