title: Antimicrobial activity of weak acids in liquid feed fermentations, and its effects on yeasts and lactic acid bacteria.
abstract: BACKGROUND
  The efficacy of weak organic acids in the control of yeasts in pig liquid feed was studied taking into account the effects on lactic acid bacteria (LAB) responsible for beneficial fermentation.
  
  
  RESULTS
  The yeast population in pig liquid feed was taxonomically identified. Kazachstania exigua, Debaryomyces hansenii and Pichia deserticola dominated the fermentation in liquid feed and whey. Pichia deserticola was found in whey and foaming liquid feed and dominated the fermentation after incubation. The sensitivity of the isolates against weak acids was measured in culture medium as well as in fermented and non-fermented liquid feed. Formic acid and potassium sorbate successfully reduced the growth of yeasts in all media without interfering with LAB development. Both of these organic acids showed an increased antifungal effect when used in liquid feed fermented by a Lactobacillus plantarum strain.
  
  
  CONCLUSIONS
  The loss of energy, reduced palatability and other practical problems due to the high growth of yeasts in fermented liquid diets can be reduced by organic acids without affecting lactic acid fermentation.
authors.affiliation: Nutrition and Food Biotechnology, Applied Biotechnology, Department of Biosciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland. Carme.Plumed@uef.fi
authors.forename: Carme
authors.initials: C
authors.lastname: Plumed-Ferrer
authors.forename: Atte
authors.initials: A
authors.lastname: von Wright
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology; D005285:Fermentation; D005516:Food Microbiology; D005520:Food Preservatives / Q000494:pharmacology; D005561:Formates / Q000494:pharmacology*; D056546:Lactobacillales / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D048191:Lactiplantibacillus plantarum / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D008894:Milk Proteins / Q000378:metabolism; D010802:Phylogeny; D010843:Pichia / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D012331:RNA, Fungal / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D004718:Saccharomycetales / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D012820:Silage / Q000382:microbiology*; D013011:Sorbic Acid / Q000494:pharmacology*; D013045:Species Specificity; D034421:Sus scrofa; D000067816:Whey Proteins; D015003:Yeasts / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification
chemical_list: D000890:Anti-Infective Agents; D000935:Antifungal Agents; D005520:Food Preservatives; D005561:Formates; D008894:Milk Proteins; D012331:RNA, Fungal; D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S; D000067816:Whey Proteins; C030544:formic acid; D013011:Sorbic Acid