Effect of propionic and lactic acids on in vitro ruminal bacteria growth

Abstract

-The objective of this work was to evaluate the effect of the levels of lactic and propionic acids on in vitro fermentation of ruminal microorganisms. In experiment 1, the levels, in a total of 12 were the following: addition of 0 (control 1), 50, 100, 150, 200 and 250 mM of lactic acid and 0 (control 2), 50, 100, 150, 200 and 250 mM of propionic acid, respectively, in incubation flasks, which contained ruminal inoculum, glucose and synthetic culture medium, with two repetitions for each combination. In experiment 2, the combinations, in a total of 4, were the following: presence of 12 and 24 mM of propionic acid and 0 mg of glucose, respectively; presence of 12 and 24 mM of propionic acid and 40 mg of glucose, respectively, to the incubation flasks which contained ruminal inoculum, with or without glucose and in synthetic culture medium with two repetitions each. There was no effect on the specific growth velocity of ruminal microorganisms in the presence of lactic acid or propionic acid. However, when there were greater concentrations of these acids in the media, there was a longer lag phase in the microorganism phase. Acid propionic at the concentration of 24 mM inhibited the production of acid acetic and butyric acid in a media with glucose. Despite of not being used as a source of energy by the ruminal microorganisms, propionic acid affects their metabolism. Lactic and propionic acids inhibit growth of some ruminal microorganisms at elevated concentrations.

The Role of Selected Lactic Acid Bacteria on Organic Acid Accumulation during Wet and Spray-Dried Fish-Based Silages. Contributions to the Winning Combination of Microbial Food Safety and Environmental Sustainability

“…In the current study, lactic, propionic and acetic acids were the main organic acids quantified in the spray-dried silages. The strength of lactic acid is relatively high (when compared, for instance, with acetic, propionic and formic acids) and its formation might result in a marked pH decrease, thus preventing synthesis of microbial proteins [21,50,51]. Lactic acid content of spray-dried acid silages were the highest in fish processing waste (4259.58 mg/100 g) and the lowest in klunzinger's pony fish (1426.59 mg/100 g).…”

“…Lactic and acetic acids produced by LAB play an important role upon growth inhibition of food-borne spoilage, ropiness, and pathogenic microorganisms in fermented food and feed [19,20]. As examples, propionic acid and, mainly, lactic acid at high concentrations exhibited antimicrobial activity against some species of ruminal bacteria [21]. In the presence of organic acids such as acetic, lactic, and succinic acids Pediococcus acidilactici K10 demonstrated great in-vitro growth inhibiting ability against the pathogenic strain Escherichia coli O157:H7 [22].…”