Lactic acid bacteria are mainly involved in lactic acid fermentation and produce most of the lactic acids. But there are some bacteria and few fungi that use the lactic acid fermentation process. Let see the answer to what organisms use lactic acid fermentation.
What organisms use lactic acid fermentation?
Bacteria that carries lactic acid fermentation process are of four types
- Lactic Acid Bacteria (LAB),
- Escherichia coli,
- Corynebacterium glutamicum, and
- Bacillus strains
Lactic acid bacteria are mainly found in the products of milk, meats and plants. Lactic acid bacteria are classified into three group on the basis of end product of fermentation. They are obligate homofermenters, facultative heterofermenters and obligate heterofermenter.
Obligate homofermentative lactic acid bacteria include Enterococcus faecium, Enterococcus faecalis Lactobacillus acidophilus, Lactobacillus lactis , Lactobacillus delbrueckii, Lactobacillus salivarius, Pediococcus pentocacus, Streptococcus thermophiles, Pediococcus acidilactici, and Pedicoccus damnosus,,
Facultative homofermentative lactic acid bacteria include Lactobacillus bavaricus, Lactobacillus casei, Lactobacillus coryniformis, Lactobacillus curvatus. Lactobacillus plantarum,and Lactobacillus sake ,
Heterofermentative lactic acid bacteria include Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus cellobiosus, Lactobacillus confuses, Lactobacillus coprophilus, Lactobacillus fermentatum Lactobacillus sanfrancisco, Leuconostoc dextranicum, Leuconostoc mesenteroides, and Leuconostoc paramesenteroide.
But in taxonomic classification, Lactic Acid Bacteria are grouped into two distinct phyla like Firmicutes and Actinobacteria.
Firmicutes phylum genera of lactic acid bacteria include Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Pediococcus, Streptococcus, Enterococcus, Tetragenococcus, Aerococcus, Carnobacterium, Weissella, Alloiococcus, Symbiobacterium and Vagococcus belong.
Actinobacteria phylum genera of lactic acid bacteria include Atopobium and Bifidobacterium genus.
Although most of the lactic acid are produced by lactic acid bacteria, some of the lactic acids are produced by fungi like Rhizopus, Monilla and Mucor. These fungi uses chemically defined medium that is why the purification process of the end products is quite simple. Therefore the fungal fermentation causes a great advantages in the food industry. These fungi produces ethanol and fumaric acid as by-products in lactic acid fermentation process. The production of these by-products results in lower production of lactic acids. This the disadvantages of fungal use in lactic acid fermentation process.
Larger amount of nutrient supply is needed to proceed any kind of fermentation process. Yeast is the key nutrient source for many fermentation processes to proceed. As a nutrient source, yeast is important because it can tolerate very low pH (1.5).
Although the use of wild type yeast in lactic acid fermentation process causes a low production of lactic acids, the genetically modified yeast produces a higher amount of lactic acids. Several yeast of species like Saccharomyces, Candida, Zygosaccharomyces, and Pichia are genetically engineered to produce larger amount of lactic acid. But the use of yeast in lactic acid fermentation process as nutrient source is very expensive.
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