Antifungal Activity of Lactic Acid Bacteria Combinations in Dairy Mimicking Models and Their Potential as Bioprotective Cultures in Pilot Scale Applications

Abstract

Consumer's demand for naturally preserved food products is growing and the use of bioprotective cultures is an alternative to chemical preservatives or a complementary tool to hurdle technologies to avoid or delay fungal spoilage of dairy products. To develop antifungal cultures for the dairy product biopreservation, experiments were conducted both in vitro and in situ. Firstly, the antifungal activity of 32 strains of lactic acid bacteria (LAB) and propionibacteria was screened alone, and then on combinations based on 5 selected lactobacilli strains. This screening was performed in yogurt and cheese models against four major spoilage fungi previously isolated from contaminated dairy products (Penicillium commune, Mucor racemosus, Galactomyces geotrichum, and Yarrowia lipolytica). Selected combinations were then tested as adjunct cultures in sour cream and semi-hard cheeses produced at a pilot scale to evaluate their antifungal activity during challenge tests against selected fungal targets (P. commune, M. racemosus, and Rhodotorula mucilaginosa) and shelf life tests; and their impact on product organoleptic properties. The screening step allowed selecting two binary combinations, A1 and A3 composed of Lactobacillus plantarum L244 and either Lactobacillus harbinensis L172 or Lactobacillus rhamnosus CIRM-BIA1113, respectively. In situ assays showed that the A1 combination delayed the growth of P. commune, M. racemosus and R. mucilaginosa for 2–24 days on sour cream depending of the antifungal culture inoculum, without effect on organoleptic properties at low inoculum (106 colony-forming units (CFU)/mL). Moreover, the A1 and A3 combinations also delayed the growth of P. commune in semi-hard cheese for 1–6 days and 1 day, respectively. Antifungal cultures neither impacted the growth of starter cultures in both sour cream and cheese nor the products' pH, although post acidification was observed in sour cream supplemented with these combinations at the highest concentrations (2.107 CFU/mL). The combination of both in vitro and in situ screening assays allowed developing 2 antifungal combinations exhibiting significant antifungal activity and providing future prospects for use as bioprotective cultures in dairy products.

Comparative Genomics of the Transport Proteins of Ten Lactobacillus Strains

“…All ten strains examined have homologs of pore-forming toxins (PFTs), although most of these toxins, prevalent in the lactobacilli, are bacteriocins. Many of the toxins identified in the strains have antifungal properties; the antifungal effects of lactobacilli have been studied in some detail [ 88 , 89 , 90 ]. Some of the toxic proteins, however, have pathogenic effects on mammalian cells.…”

Mechanistic Insights Into Probiotic Properties of Lactic Acid Bacteria Associated With Ethnic Fermented Dairy Products

“…Probiotics isolated from traditional dairy products comprise species of lactic acid bacteria with a history of safe use. The employment of live bacteria incorporated in food is included in the European Qualified Presumption of Safety list (Leyva Salas et al., 2018). Many probiotic lactic acid bacterial strains isolated from different dairy products have also undergone review and testing and have fulfilled the FDA “GRAS” status for use in fermented dairy product and other food items.…”

Sensitivity of Molds From Spoiled Dairy Products Towards Bioprotective Lactic Acid Bacteria Cultures

“…Using the overlay method, several studies have found different species of LAB to have strong antifungal activity. This includes Inglin et al (2015) , who reported both antifungal and antibacterial activity of LAB species; Garnier et al (2018) , who found that Mucor racemosus and P. commune could be inhibited by certain L. rhamnosus and L. plantarum cultures, and Salas et al (2018) , who found that a mixture of Lactobacillus harbinensis ( L. harbinensis ) and L. plantarum exhibited inhibitory effect on Mucor and Penicillium strains.…”