Influence of Fermentation Medium Composition on Physicochemical Surface Properties of Lactobacillus acidophilus

Abstract

The effect of the simple and complex basic components of a fermentation medium on the surface properties of Lactobacillus acidophilus NCC2628 is studied by physicochemical methods, such as electrophoresis, interfacial adhesion, and X-ray photonelectron spectroscopy, and by transmission electron microscopy. Starting from an optimized complete medium, the effect of carbohydrates, peptones, and yeast extracts on the physicochemical properties of the cell wall is systematically investigated by consecutively omitting one of the principal components from the fermentation medium at the time. The physicochemical properties and structure of the bacterial cell wall remain largely unchanged if the carbohydrate content of the fermentation medium is strongly reduced, although the concentration of surface proteins increases slightly. Both peptone and yeast extract have a considerable influence on the bacterial cell wall, as witnessed by changes in surface charge, hydrophobicity, and the nitrogen-to-carbon ratio. Both zeta potential and the cell wall hydrophobicity show a positive correlation with the nitrogen-to-carbon ratio of the bacterial surfaces, indicative of the important role of surface proteins in the overall surface physical chemistry. The hydrophobicity of the cell wall, which is low for the cultures grown in the complete medium and in the absence of carbohydrates, becomes fairly high for the cultures grown in the medium without peptones and the medium without yeast extract. UV spectrophotometry and sodium dodecyl sulfate-polyacrylamide gel electrophoresis combined with liquid chromatographytandem mass spectrometry are used to analyze the effect of medium composition on LiCl-extractable cell wall proteins, confirming the major change in protein composition of the cell wall for the culture fermented in the medium without peptones. In particular, it is found that expression of the S-layer protein is dependent on the protein source of the fermentation medium.

Effect of Environmental Stresses on S-Layer Production in Lactobacillus acidophilus ATCC 4356

“…Schar-Zammaretti (2005) suggested that S-layer protein is preferentially expressed under different fermentation media. Furthermore, it has been shown that the S-layer production is changed with the change in medium (such as bile salt, penicillin G) (Khaleghi et al, 2010(Khaleghi et al, , 2011.…”

“…There is some evidence that the surface properties of microorganisms are dependent on the growth conditions and the composition of the fermentation medium (Schar-Zammaretti et al, 2005;Waar et al, 2002;Dufrene & Rouxhet, 1996;Millsap et al, 1997). Schar-Zammaretti (2005) suggested that S-layer protein is preferentially expressed under different fermentation media.…”

“…However, no general function has been identified for S-layer proteins, but several lactobacillar S-layers have been identified as putative adhesions with affinity for intestinal epithelial cells, extracellular matrices and/ or to lipoteichoic acid (LTA) of other bacterial species (Avall-Jaaskelainen & Palva, 2005;Buck et al, 2005;Frece et al, 2005;Garrote et al, 2004;Hynonen et al, 2002;Kos et al, 2003;Velez et al, 2007;Vidgren et al, 1992). Of the various roles proposed for the bacterial S-layer, it is a protective sheath against hostile environment (Avall-Jaaskelainen & Palva, 2005;Frece et al, 2005;Khaleghi et al, 2010Khaleghi et al, , 2011Kos et al, 2003;Schar-Zammaretti et al, 2005). Adhesive S-layers have a role in inhibition of adhesiveness of pathogenic bacteria and thus can contribute to probiotic effects of lactobacilli.…”

Influence of carbohydrates on cell properties of Lactobacillus rhamnosus

“…Still, detailed analyses of the relationship between LAB cell wall constituents and physicochemical properties are slowly emerging. It has been demonstrated that components of growth medium (such as yeast extract and peptones) present an important factor in determining the surface properties of lactobacilli, including structure and physicochemical characteristics of bacterial cell wall [10]. A better knowledge of these aspects could help us understand the roles that different cell surface constituents have in bacterial behavior.…”

“…The surface properties of bacteria are vital for their survival and interactions with the environment, including that with other microorganisms and host organisms [10]. Frequently, the behavior of LAB is dependent on the cell surface physicochemical properties and their chemical composition [11].…”