We investigated the mucus-binding properties of aggregating and non-aggregating potentially probiotic strains of kefir-isolated Lactobacillus kefiri, using different substrates. All the strains were able to adhere to commercial gastric mucin (MUCIN) and extracted mucus from small intestine (SIM) and colon (CM). The extraction of surface proteins from bacteria using LiCl or NaOH significantly reduced the adhesion of three selected strains (CIDCA 8348, CIDCA 83115 and JCM 5818); although a significant proportion (up to 50%) of S-layer proteins were not completely eliminated after treatments. The surface (S-layer) protein extracts from all the strains of Lb. kefiri were capable of binding to MUCIN, SIM or CM, and no differences were observed among them. The addition of their own surface protein extract increased adhesion of CIDCA 8348 and 83115 to MUCIN and SIM, meanwhile no changes in adhesion were observed for JCM 5818. None of the seven sugars tested had the ability to inhibit the adhesion of whole bacteria to the three mucus extracts. Noteworthy, the degree of bacterial adhesion reached in the presence of their own surface protein (S-layer) extract decreased to basal levels in the presence of some sugars, suggesting an interaction between the added sugar and the surface proteins. In conclusion, the ability of these food-isolated bacteria to adhere to gastrointestinal mucus becomes an essential issue regarding the biotechnological potentiality of Lb. kefiri for the food industry.

Group B streptococcus (GBS) is a leading cause of neonatal sepsis and meningitis. We determined the distribution of serotypes and surface protein encoding genes of GBS strains from pregnant and non-pregnant women in Egypt. Vaginal swabs from 364 women were screened by culture and 100 (27·4%) yielded GBS. Serotype V was the most predominant (33%), followed by serotypes II (17%), III (15%), Ia (14%), VI (12%), Ib (8%) and IV (1%). The most common surface protein genes were epsilon (27%), alp3 (26%), bca (18%), rib (16%) and alp2 (10%). Two isolates were negative for surface protein genes. The distribution of serotypes and surface proteins was similar to reports from other parts of the world but the relatively high frequency of serotype VI was a notable feature of the strains from women in Egypt.

Living, intact protoscoleces of the British horse and sheep strains of Echinococcus granulosus were subjected to surface radioiodination procedures using 125I and Iodogen and 125I-Bolton Hunter reagent. Subsequent combined electron microscopy and autoradiography revealed specific surface membrane labelling with the Iodogen procedure, but significant tegumental labelling with the Bolton-Hunter reagent. The two parasite strains yielded different profiles of electrophoretically separated labelled proteins; the Iodogen method, not surprisingly, resulted in a less complex pattern of labelled polypeptides than the Bolton and Hunter reagent.

Several microbial interactions involving yeast and lactobacilli have been suggested in fermented products. Co-aggregation between Lactobacillus kefir and yeast Saccharomyces lipolytica isolated from kefir grains was studied by scanning electron microscopy and aggregation assays. Six out of twenty Lb. kefir strains were able to co-aggregate with Sacch. lipolytica CIDCA 812 and showed thermolabile non-covalently bound surface molecules involved in this interaction. Co-aggregation inhibition after Lb. kefir pre-treatment with 5 m-LiCl or 20 g SDS/l showed that bacterial S-layer proteins play an important role in this interaction. Presence of different sugar (mannose, sucrose and fructose) or yeast pre-treatment with sodium periodate inhibited co-aggregation between Lb. kefir and Sacch. lipolytica. Co-aggregating Lb. kefir strains were also able to agglutinate with human red blood cells and they lost this ability after treatment with 5 m-LiCl. These results and the capacity of purified S-layer proteins of Lb. kefir to haemagglutinate, strongly suggest that a lectin-like activity of bacterial surface proteins (S-layer) mediates the aggregation with yeast cells.

An understanding of the biology of the cuticle in the larval stages of Ascariodea is of importance since the cuticle molecules not only possess a variety of functions related to survival but also have a potential role as a target for immunoprophylaxis. Thus, we made a preliminary characterization of surface proteins and antigens from 3rd-stage larvae (L3) and lung-stage larvae of Ascaris suum using two biotin-derivatives and two-dimensional polyacrylamide gel electrophoresis (2D–PAGE). The proteins labelled with biotin comprised a total of 37 and 32 spots, with molecular weights (Mr) ranging from 15 to 101kDa and isoelectric points (pI) from 3·8 to 7·6, in L3 and lung-stage larvae, respectively. The profiles revealed that the individual spots bound to one or both biotin derivatives. In addition, stage-common and stage-specific spots were found in L3 and lung-stage larvae. 2D–PAGE/immunoblotting analysis was performed with antisera from rabbits repeatedly inoculated with A. suum L3. Nineteen spots were recognized as surface antigens, with Mr ranging from 32 to 66kDa and pI from 4·9 to 7·6, from L3 and lung-stage larvae after alignment of the immunoblots with the profile of the surface proteins. These spots were found to include stage-common and stage-specific antigens. Identification of surface proteins by biotin labelling combined with 2D–PAGE allows a substantial shortening of sample preparation time for the target proteins, and will be a viable method for protein analysis of surface proteins and antigens of A. suum L3 and lung-stage larvae.