Citrate metabolism by Enterococcus faecium and Enterococcus durans isolated from goat’s and ewe’s milk: influence of glucose and lactose

Abstract

Citrate metabolism by Enterococcus faecium ET C9 and Enterococcus durans Ov 421 was studied as sole energy source and in presence of glucose or lactose. Both strains utilized citrate as the sole energy source. Enterococcus faecium ET C9 showed diauxic growth in the presence of a limiting concentration of glucose. Neither strain used citrate until glucose was fully metabolized. The strains showed co-metabolism of citrate and lactose. Lactate, acetate, formate, and flavour compounds (diacetyl, acetoin, and 2,3-butanediol) were detected in both strains. The highest production of flavour compounds was detected during growth of E. durans Ov 421 in media supplemented with citrate-glucose and citrate-lactose. Citrate lyase was inducible in both strains. Acetate kinase activities presented the highest values in LAPTc medium, with E. faecium ET C9 displaying a specific activity 2.4-fold higher than E. durans. The highest levels of alpha-acetolactate synthase specific activity were detected in E. durans grown in LAPTc+g, in accordance with the maximum production of flavour compounds detected in this medium. Diacetyl and acetoinreductases displayed lower specific activity values in the presence of citrate. Enterococcus faecium and E. durans displayed citrate lyase, acetate kinase, alpha-acetolactate synthase, and diacetyl and acetoin reductase activities. These enzymes are necessary for conversion of citrate to flavour compounds that are important in fermented dairy products.

Ester synthesis by lactic acid bacteria isolated from goat’s and ewe’s milk and cheeses

“…These strains were previously selected for their ability to produce flavour compounds from sugars, citrate and proteins, and for their esterase-lipase activities (Abeijón et al, 2006;Cabral, Abeijón Mukdsi, Medina, & González, 2007;Katz et al, 2002;Oliszewski et al, 2007). Enterococcus strains were previously tested for vancomycin/teicoplanin resistance and haemolysin and gelatinase production (Katz, 2005;Oliszewski, 2006).…”

Interaction between Galactomyces geotrichum KL20B, Lactobacillus plantarum LAT3 and Enterococcus faecalis KE06 during Milk Fermentation

“…The major consumption was revealed for E. faecalis KE06 culture, in which citrate was metabolized with the production of acetate. The co-metabolism of lactose and citrate has been previously reported for E. faecalis FAIR-E-229 [26], E. faecium ET C9 and E. durans Ov 421 [27].…”

Crosstalk Between Intestinal Microbiota Derived Metabolites and Tissues in Allogeneic Hematopoietic Cell Transplantation

“…Particularly, Enterococcus faecium and some Enterococcus faecalis encode genes related to lactose and galactose metabolism (42). Enterococcus faecium metabolizes citrate and lactose to produce lactate, whereas E. faecalis can produce superoxide and H 2 O 2 that damage colonic epithelial cells (94,95). These enterococci require lactose for growth in vitro (lactose auxotroph) and are associated with intestinal inflammation and damages (96).…”