Growth Kinetics of Probiotic Lactobacillus Strains in the Alternative, Cost-Efficient Semi-Solid Fermentation Medium

SIMPLE SUMMARY: Commercial microbiological media are often expensive because of used ingredients; therefore, their application in high-density cell production is cost-consuming. Since Lactobacillus bacteria are commonly used in various industries, and especially as probiotics, alternative cheaper media are needed. Additionally, the approach is to use food or agriculture by-products, which can support the growth of bacteria due to their components. Among them, cereals and flours are used worldwide; therefore, their usage as a medium for Lactobacillus spp. can be accessible, easy, and affordable. Results obtained from the following study showed that a mixture of wheat, barley, maize, and rye flours combined with distilled water is a good medium for the efficient growth of selected probiotic Lactobacillus spp. ABSTRACT: The growing need for Lactobacillus bacteria usage in industry and the expending probiotic market led to a search for new cost-efficient fermentation media from which a high yield of these bacteria could be obtained. The following study aimed to elaborate cultivation medium, for Lactobacillus spp. growth, which main components would be wheat, maize, barley, and rye flours. The optimal temperature for Lactobacillus growth in new semi-solid fermentation (SSF) medium, water content, and pH of the medium were analyzed by the plate count method. It was established, that the highest bacteria counts were obtained from cultures conducted in the SSF medium with flours to water ratio of 1:1.5 with a natural pH of 6.0 at 37 °C. Subsequently, the growth kinetics of analyzed strains, in both MRS and the SSF media, were studied. The newly designed media contributed to the increased duration of selected Lactobacillus strains lag phase, which varied from 1.98 to 5.64; nevertheless, the maximum growth rate of the strains was two times higher in the SSF medium rather than in MRS, which also resulted in shorter generation time. The developed medium has the potential to become a new cost-efficient fermentation medium for Lactobacillus spp.