Production of vitamin B12 via microbial strains isolated from marine and food sources in Egypt

Abstract

Background Vitamin B12 is a very important water-soluble vitamin, which was first isolated from the liver as an anti-pernicious anemia factor. The sole source of vitamin B12 is the animal-based food. It has a complicated structure and requires expensive multi-steps to be synthesized chemically. Intriguingly, vitamin B12 can be produced through microbial fermentation by microorganisms in a cheap and more effective manner. Objective This study aims to isolate and characterize microorganisms that have the capability to produce vitamin B12. In addition, the current work aims to optimize the vitamin B12 production conditions by isolating strains using suitable waste materials to obtain a high vitamin B12 yield. Materials and methods Different bacterial and yeast isolates were isolated from marine and food samples using the pour-plate technique. These isolates were screened for vitamin B12 production using a specific growth medium that lacked vitamin B12 and a test indicator bacterium. The content of vitamin B12 was estimated using spectrophotometer measurement and high-performance liquid chromatography (HPLC). The isolates that showed high vitamin B12 productivity were identified using MALDI-TOF technique. The identified strains were implemented for the optimization of vitamin B12 production to reveal the most proper and optimum conditions for the production. Response surface methodology (RSM) was employed to enhance the production of vitamin B12 in a flask scale. Agro-industrial wastes such as molasses were used for vitamin B12 production using the most optimum conditions as determined by RSM. Results and conclusion Eighty-seven actinomycetes, bacterial, and yeast isolates were screened for vitamin B12 production. Out of these isolates, 15 showed high vitamin B12 productivity. We found that bacilli and yeast isolates were the most productive among the tested cocci and actinomycetes isolates. The highly productive Bacillus and yeast isolates were identified using the MALDI-TOF analysis. The isolates were identified as Candida pelliculosa, Geotrichum candidum, Bacillus subtilis and Bacillus sp. One strain of Candida pelliculosa (coded BYI), three strains of Geotrichum candidum (coded as MZYC, MZYD, and MZYG) were selected for studying the effect of sugar type and inoculum size on the yield of vitamin B12 production. Strain MZYD was selected for the statistical modelling using RSM to optimize seven factors for the vitamin B12 production. These factors included temperature, fermentation time, salt concentration, pH, sugar concentration, inoculum size, and aeration. Five factors i.e., temperature, pH, sugar concentration, and inoculum size were shown to significantly improve the vitamin B12 production. A maximum yield of 64.21 μg/100 ml was obtained using the optimized RSM conditions. These optimized conditions were used to produce vitamin B12 using molasses as a raw material for the microbial growth.