High-throughput screening for texturing Lactococcus strains

• Published in: FEMS microbiology letters Vol. 366; no. 2; pp. 1 - 7
• Main Authors: Poulsen, Vera Kuzina, Derkx, Patrick, Oregaard, Gunnar
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.01.2019
• Subjects: Animals; Backup software; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cattle; Cheese - analysis; Cheese - microbiology; Cultured milk; Dairy industry; Dairy products; Eps gene; Fermentation; Fermented milk products; Food industry; Food Microbiology; Food processing industry; Gene clusters; Genes; Genomics; High-throughput screening; High-throughput screening (Biochemical assaying); Identification and classification; Lactic acid; Lactic acid bacteria; Lactococcus; Lactococcus lactis - classification; Lactococcus lactis - genetics; Lactococcus lactis - isolation & purification; Lactococcus lactis - metabolism; Measurement methods; Methods; Microbiology; Milk; Milk - chemistry; Milk - microbiology; Mining industry; Physiological aspects; Polysaccharides; Properties; Research Letter; Rheological properties; Rheology; Screening; Shelf life; Strains (organisms); Texture; Texturing; Time; Denmark; polysaccharide; screening; texture
• ISSN: 1574-6968; 0378-1097; 1574-6968
• DOI: 10.1093/femsle/fnz001

Abstract In the food industry, lactic acid bacteria (LAB) are used in dairy fermentations, extending the shelf life by lowering the pH and also affecting taste and texture of the fermented milk. The texture of fermented milk is an important quality parameter, affecting consumer acceptance. Finding LAB providing desired texture of a product is time consuming and laborious when using standard methods for measuring texture, e.g. rheology measurements. Screening of 986 Lactococcus lactis strains resulted in few strains with the ability to enhance texture, demonstrating the necessity of implementation of high-throughput screening methods. A high-throughput screening assay was developed, combining small-scale 96-well microtiter plates and pressure measurements during liquid handling, e.g. aspiration, to find strains that give good texture in fermented milk. Only about 1% of the strains were found to enhance milk texture. Two of the texturing strains belong to L. lactis subsp. lactis, which are the first texturing strains from this subsp. reported. Mining for eps gene clusters responsible for exocellular polysaccharide production was performed, as polysaccharide production can contribute positively to fermented milk texture. Comparative genomics approach revealed four types of texturing L. lactis strains with diverse eps gene clusters. Novel method for high-throughput screening for texturing Lactococcus strains and comparative genomics of gene clusters for polysaccharide production.