The influence of the ph and various concentrations of salt and bile on the growth of enterococci isolated from natural ecosystems

Abstract

The article presents the results of the studies on ability of four un explored strains of enterococci isolated from the traditional Carpathian cheese to survive at different pH values under high concentrations of salt (sodium chloride) and bile. The lowp Hin the stomach and bileacid swhichen tering to the small in testine reduce the survival of bacteria, so the effectiveness of probiotics trains dependson a large extent on the irresistance to the sefactors. Saltisone of the maincomponents in the production of brinecheeses, asit influence on the enzymes activity during cheeseri pening and the formation of flavoring compounds, on the hydration of casein, and also on the shelf life of cheese. However, high concentrations of salt exhibit a bacterio staticeffect, sotheres istance of microbial cultures to saltcon centrations, which a repredicted by the technological process for brinecheeses, is really important. The results o fthe studyes tablished, that the tested strains of enterococci are not abletosurvive and exhibit growth properties at the value of pH 3 units. At the value of pH 4 units, only two strains E. durans SB18 and E. durans SB20 were ableto survive and exhibit good growth properties, as indicated by the increase in the optical density of the culture medium. At the value of pH 5, all the tested strains of enterococci showed growth properties, however, E. durans SB18 andE durans SB20 strains showed more significant growth than the control samples, in particular, the optical density of the medium increased, respectively, 9,8 and 10,8 times (p<0.001). During the studying the resistance of enterococci to different concentrations of bile, it was found out that at 20% concentration the highest growth was shown by two strains of enterococci - E. durans SB18 andE. durans SB20, the optical density of the culture medium of the sestrains were higher compared to the control on 61,9 and 58,9% (p<0.001), respectively. All the tested strains of enterococci were abletosurvive at the concentration of 3-6,5% sodium chloride for 21 days, indicating their suitability in using the minthe production of brinecheeses.

Keywords

• enterococcusdurans
• e. faecium
• optical density
• bile
• ph.