Selection of Nitrogen Source in Cultivation of Lactic Acid Bacteria
Feb 19, 2021
By Xiong Changwu
Lactic Acid Bacteria(LAB) are more and more widely used in food processing, dietary supplements and functional foods with tens of millions of strains involved. Generally speaking, lactic acid bacteria are difficult to cultivate, but the physiological characteristics of different lactic acid bacteria are significantly different. Some strains have strong synthesis and catabolism ability with low nutritional requirements, while other strains lack some metabolic pathways and have strict nutritional requirements.
(Easy to cultivate)
Rich in peptidases, can synthesize certain amino acid, vitamins and growth factors independently
Lactobacillus plantarum, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus paracasei, Bifidobacterium lactis, etc.
(Hard to cultivate)
Weak synthesis and catabolism ability, sensitive to various growth factors which need to be obtained directly from outside
Lactobacillus acidophilus, Lactobacillus reuteri, Bifidobacterium longum, Bifidobacterium infantis, etc.
Whether the nutritional requirements of lactic acid bacteria are severe or not is manifested in whether the change of the nitrogen source in the medium and the related growth factors have a significant impact on the biomass in the cultivation of lactic acid bacteria. Generally, nitrogen sources with different nutritional characteristics have no significant effect on lactic acid bacteria that are easier to cultivate.
It can be seen from some of the strains we tested that changes in nitrogen source have no significant effect on the biomass of Lactobacillus plantarum, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus paracasei and other strains under the same culture conditions. For other strains such as Lactobacillus acidophilus, Lactobacillus bulgaricus, yeast extracts with different nutritional characteristics have obvious effects, and the fluctuation of biomass can reach more than 50%.
It can be seen from the test results that Bifidobacterium lactis is less affected by yeast extracts with different nutritional characteristics, while Bifidobacterium longum is more affected by yeast extracts with different nutritional characteristics.
Based on the cultivation results of lactic acid bacteria under the same conditions, it can be seen that for the easy-to-cultivable lactic acid bacteria, Angel's nutrient-enriched yeast extract FM985 and other grades, with balanced nutrients such as protein and free amino acids, can perfectly meet the growth of such lactic acid bacteria, while for Lactobacillus acidophilus and Bifidobacterium longum, Angel's nutrient-enriched yeast extract FM502, rich in related growth factors, is more conducive to biomass.
In addition to the impact of biomass, it can be found in our application research and tests that yeast extract FM502, which is rich in special nutrients, also has a certain improvement in the shelf life of lactic acid bacteria.
The Lactobacillus acidophilus cultivated by yeast extract FM502 is stored for different periods of time at 25°C, compared with other yeast extracts, the number of viable bacteria has a higher survival rate.
Different lactic acid bacteria have different nutritional characteristics requirements. According to comprehensive application tests and customer feedback, using Angel's yeast extract FM985, FM502 and related yeast extracts solely or together can meet the growth needs of lactic acid bacteria with obtaining higher biomass and longer shelf life. The specific recommendations of different yeast extracts are as follows:
R&D expert of Protein Nutrition and Flavoring technology center