Biofilm Formation and Contamination of Cheese by Nonstarter Lactic Acid Bacteria in The Dairy Environment

Abstract

Defects in cheese, such as undesirable flavors, gas formation, or white surface haze from calcium lactate crystals, can result from growth of nonstarter lactic acid bacteria (NSLAB). The potential for biofilm formation by NSLAB during cheese manufacturing, the effect of cleaning and sanitizing on the biofilm, and bacterial growth and formation of defects during ripening of the contaminated cheese were studied. Stirred-curd Cheddar cheese was made in the presence of stainless steel chips containing biofilms of either of two strains of erythromycin-resistant NSLAB (Lactobacillus curvatus strain JBL2126 or Lactobacillus fermentum strain AWL4001). During ripening, the cheese was assayed for total lactic acid bacteria, numbers of NSLAB, and percentage of lactic acid isomers. Biofilms of L. curvatus formed during cheese making survived the cleaning process and persisted in a subsequent batch of cheese. The starter culture also survived the cleaning process. Additionally, L. curvatus biofilms present in the vat dislodged, grew to high numbers, and caused a calcium lactate white haze defect in cheese during ripening. On the other hand, biofilms of L. fermentum sloughed off during cheese making but could not compete with other NSLAB present in cheese during ripening. Pulsed-field gel electrophoresis results verified the presence of the two biofilm strains during cheese making and in the ripening cheese. Probable contamination sites in the plant for other NSLAB isolated in the cheese were identified, thus supporting the hypothesis that resident NSLAB biofilms are a viable source of contamination in the dairy environment.

The biofilm-positive Staphylococcus epidermidis isolates in raw materials, foodstuffs and on contact surfaces in processing plants

“…Subsequently, secondary contamination from contact surfaces can occur. Our results are similar with those of Somers et al (2001) who described BF on the surfaces in the cheese factories also with the subsequent contamination of the cheese produced.…”

Bacterial Community Structure and Location in Stilton Cheese

“…Closest relatives of Lactobacillus plantarum and Lactobacillus curvatus were detected; however, Lactobacillus curvatus was detected by amplifying the V3 region only. Both species usually occur in dairy ecosystems: Lactobacillus plantarum is recognized as contributing to flavor development (1,6) and as a protective antimicrobial agent in cheese (15,44), while Lactobacillus curvatus has been associated with undesirable biofilm development in the dairy environment (42,51). Leuconostoc mesenteroides was also detected, but only by the amplification of the V4-V5 region; it is often found in food matrices and in many cheeses (12,29,37,49).…”

Facility-Specific “House” Microbiome Drives Microbial Landscapes of Artisan Cheesemaking Plants

“…Hence, the processing environment may serve as an important reservoir for bidirectional microbial transfer between fermentations, and microbial surveillance of this environment is critical to understanding the complete microbial ecosystem of cheese production. In modern cheese production facilities, biofilms of psychrotrophic bacteria (3,4) and nonstarter lactic acid bacteria (5)(6)(7)(8) can form on equipment surfaces, acting as a source of contamination in successive batches of cheese. Wooden processing surfaces, including aging boards (9,10) and milk vats (11)(12)(13), are also rich sources of microbes that are important for cheese acidification and ripening.…”