Investigating the ability of wild and preserved strains of Bacillus subtilis natto to produce menaquinone 7 (vitamin K) and nattokinase
Subject Areas : Molecular Microbiology
1 - azad
Keywords: Bacillus subtilis natto, Menaquinone 7, Vitamin K, Nattokinase, Fermented food.,
Abstract :
Background & Objectives: Bacillus subtilis natto is a valuable microbial strain in pharmaceutical biotechnology due to its high pptential in the production of menaquinone 7 (vitamin K) and natto kinase. Pharmaceutical companies and food supplement manufacturers use this strain for the industrial production of these compounds. However, despite the practical importance of Bacillus subtilis natto in the pharmaceutical industry, only one strain of this bacterium is available in Iran by microbial culture collections. Considering that long-term collection preservation may have a negative effect on the physiological characteristics of bacteria, we decided to compare the ability of this strain in the production of biological products with the wild strain of Bacillus subtilis natto. Materials and Methods: Fermented Japanese food natto was prepared by purchasing natto starter from international companies and importing it into the country. The natto suspension was diluted and cultured with the desired bacteria, which were then isolated and purified. Colonies which were suspected to Bacillus subtilis were isolated based on colony morphology, Gram staining, and spore staining. Subsequently, biochemical tests were performed on the isolates, including citrate utilization, starch hydrolysis, gelatin hydrolysis, hydrogen sulfide production, salt tolerance, catalase, Voges-Proskauer (V-P), glucose fermentation, mannitol fermentation. and nitrate reduction. Molecular identification was carried out using 16S rRNA gene sequencing and the obtained sequence was registered in the NCBI database. Finally, the ability of wild and collection strain of Bacillus subtilis natto to produce menaquinone 7 and nattokinase was compared. Results: The results obtained from the colony morphology tests, staining, biochemical tests, and molecular identification confirmed that the isolated strain was Bacillus subtilis natto. The amount of menaquinone 7 produced by this strain and the collection strain did not show a significant difference. Natokinase production potency was significantly higher in the wild strain compared to the collection strain. Conclusion: Long-term storage of Bacillus subtilis natto in microbial collections outside the country, followed by storage in domestic collections, has resulted in a significant decrease in the ability of this strain to produce valuable pharmaceutical products. However, this conclusion cannot be definitively confirmed, as it is possible that the collection strain available in Iran was initially a weak strain in terms of pharmaceutical production. Given the importance of industrial strains in the production of valuable products, it is unlikely that international microbial collections have provided strains with high production potential to other countries. Therefore, efforts will be made to deposit the wild Bacillus subtilis natto strain, which has significant potential for producing menaquinone 7 and nattokinase, in domestic microbial culture collections so that it be made available to Iranian technologists and researchers.
