Cell surface hydrophobicity of Actinomyces pyogenes determined by hexadecane adherence- and salt aggregation studies

Characterization of Streptomyces Cell Surface by the Microbial Adhesion to Solvents Method

The cell surface physicochemical properties of Streptomyces should influencing the dispersal and adsorption of spores and hyphae in soil and should conditioning there interactions with organic or metal substances in the bioremediation of contaminated environment. These properties are concerning surface hydrophobicity, electron donor/acceptor, and charge surface. To date, only hydrophobicity of Streptomyces was studied by contact angle measurements and microbial adhesion to hydrocarbons (MATH). In this work, we studied the electron donor/acceptor character of the Streptomyces cell surface in two ionic strength 10^-3 M and 10^-1 M of KNO₃. Thus, to facilitate the characterisation of the surfaces of microbial cells, we used a simple, rapid, and quantitative technique, the microbial adhesion method to solvents (MATS), which is based on the comparison of the affinity of microbial cells for a monopolar solvent with a polar solvent. The monopolar solvent can be acid (electron acceptor) or basic (electron donor), but both solvents should have a surface tension similar to that of the Kifshitz van der Waals components. At the significant ionic strength of the biological medium, the electron donor character is well expressed for all 14 Streptomyces strains with very significant differences among them ranging from 0% to 72.92%. When the cells were placed in a solution with a higher ionic strength, we were able to classify the donor character results into three categories. The first category is that the weak donor character of strains A53 and A58 became more expressed at 10^-1 M KNO₃ concentration. The second category is that three strains A30, A60, and A63 expressed a weaker character in a higher ionic strength. For the other strains, no expression of the donor trait was obtained at higher ionic strength. In a suspension with a concentration of 10^-3 KNO₃, only two strains expressed an electron acceptor character. This character is very important for strains A49, A57, A58, A60, A63, and A65 at 10^-1M KNO₃. This work has shown that these properties vary greatly depending on the Streptomyces strain. It is important to consider the change in physicochemical properties of surface cells with ionic strength when using Streptomyces in different bioprocesses.

Lactic acid bacteria in Hamei and Marcha of North East India

Hamei and Marcha are mixed dough inocula used as starters for preparation of various indigenous alcoholic beverages in Manipur and Sikkim in India, respectively. These starters are traditionally prepared from rice with wild herbs and spices. Samples of Hamei and Marcha, collected from Manipur and Sikkim, respectively, were analysed for lactic acid bacterial composition. The population of lactic acid bacteria (LAB) was 6.9 and 7.1 Log cfu/g in Hamei and Marcha, respectively. On the basis of phenotypic and genotypic characters, LAB strains isolated from Hamei and Marcha were identified as Pediococcus pentosaceus, Lactobacillus plantarum and Lactobacillus brevis. Technological properties of LAB such as antimicrobial properties, effect on acidification, ability to produce biogenic amines and ethanol, degree of hydrophobicity and enzymatic activities were also performed. Pediococcus pentosaceus HS: B1, isolated from Hamei, was found to produce bacteriocin. None of the strains produced biogenic amines. LAB strains showed a strong acidifying ability and they also produced a wide spectrum of enzymes.

Adherence of Actinomyces pyogenes to HeLa cells mediated by hydrophobic surface proteins

Determination of cell-surface hydrophobicity of Actinomyces pyogenes by hydrophobic interaction chromatography on phenyl-Sepharose revealed that all 42 cultures examined were strongly hydrophobic. The hydrophobic surface proteins were solubilized by mutanolysin treatment of the bacteria and isolated by hydrophobic interaction chromatography. In SDS-PAGE, they appeared with numerous protein bands and blocked the adhesion of whole bacterial cells to the gel matrix. The A. pyogenes cultures attached to HeLa cells in varying degrees. This attachment of A. pyogenes was greatly reduced in the presence of isolated hydrophobic proteins and in the presence of specific antibodies produced against hydrophobic surface proteins. The results of the present study demonstrate that hydrophobic surface proteins promote the capacity of A. pyogenes to adhere to HeLa cells.