Formation of lactic, acetic, succinic, propionic, formic and butyric acid by lactic acid bacteria

• This was the first research to investigate organic acid production by lactic acid bacteria.
• Significant differences were found in organic acid levels among bacterial strains.
• The fish infusion broth played important role in organic acid production.
• Succinic acid formation was the highest by LAB whilst acetic acid was produced at the lowest levels.
• Organic acid production varied significantly depending on bacterial strains and growth medium.

Organic acids (lactic, acetic, succinic, propionic, formic and butyric acid) production by lactic acid bacteria (LAB) were investigated in various fish infusion broth (anchovy, sea bass, tilapia and trout) and MRS broth (control) by using HPLC method. Significant differences were found in organic acid levels (P < 0.05) among bacterial strains. Succinic acid formation was the highest by LAB whilst acetic acid was produced at the lowest levels. The highest lactic acid production was observed with Lactobacillus lactis subsp. lactis and Pediococcus acidilactici in anchovy infusion broth, with values of 2403 and 2345 mg/L, respectively. Acetic acid production was 822 and 803 mg/L by Lactobacto acidophilus and Lactobacillus delbrueckii subsp. lactis in anchovy infusion broth, respectively while succinic acid production ranged from 142 mg/L by Lb. delbrueckii subsp. lactis in sea bass infusion broth to 9231 mg/L by Lb. lactis subsp. lactis in MRS broth. Propionic acid formation by Pc. acidilactici was 3747 mg/L in sea bass infusion broth whereas Lb. lactis subsp. cremoris produced less than that in MRS broth. The result of the study indicated that LAB strains had a great ability to produce succinic acid. Also other organic acid production varied significantly depending on bacterial strains and growth medium.