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In this work, a fermentation starter involving autochthonous strains obtained from an artisanal dry sausage from Colonia Caroya (Córdoba, Argentina) was formulated, with the aim of preserving the typicity that characterizes this artisanal meat product. Isolates of lactic acid bacteria (LAB) and coagulase-negative-cocci (CNC) were obtained, identified and typified using 16S rRNA gene sequences and RAPD-PCR reactions. Some technological and safety-related properties were also studied: 1-resistance to low pH and high salt concentration, 2-proteolytic and lipolytic activities, 3-antibiotic resistance against tetracycline, kanamycin, vancomycin and ampicillin, and 4-absence of histidine decarboxylase (hdc) gene. A bacterial consortium of one LAB (Latilactobacillus sakeiUNQLs16) and five CNC selected strains with the best features was used to formulate a meat fermentation starter (UNQ-MFS), which was compared with a commercial one (C-MFS), in a pilot-scale sausage production. Certain technological parameters (pH and weight reduction, microbial counts, and final texture profiles) were assessed in both batches to ensure the appropriate development of the process. The strains implantation was followed using RAPD-PCR: L. sakeiUNQLs16 showed dominance throughout the process and its implantation was confirmed in the batch inoculated with UNQ-MFS, whereas isolates obtained from the C-MFS were not detected in the batch inoculated with this commercial starter. The fermentative starter design with native strains is not only relevant for the regional producers, but also to expand the knowledge and increase the number and diversity of available strains capable of leading the fermentative processes, contributing to safety and quality of foodstuffs.

Seventeen heterofermentative lactobacilli isolated from kefir grains were characterized by molecular methods. Bacterial isolates were identified by amplification of 16S rRNA gene and analysis by Amplified Ribosomal DNA Restriction Analysis (ARDRA), using the restriction enzymes Hae III, Dde I, and Hinf I. ARDRA analysis of lactobacilli isolates showed, for each enzyme used, a same banding pattern between the heterofermentative lactobacilli and the reference strains Lactobacillus kefir JCM 5818 and Lb. kefir ATCC 8007. Other reference lactobacilli and one homofermentative isolate showed differences in at least one of these patterns. The 16S-23S rRNA spacer region was also used to discriminate the bacterial isolates at the species level. The data obtained from the analysis of spacer region confirmed that sequencing of this genome region is a good tool for a reliable identification of members of Lb. kefir species. Genotyping of isolates was performed by Random Amplified Polymorphic DNA (RAPD-PCR) analysis using M13, Coc, ERIC-2 and 1254 primers. Patterns obtained allowed the differentiation of isolates in three groups. The three clusters showed by RAPD-PCR analysis could be correlated with at least three different strains of Lb. kefir species in the group of heterofermentative lactobacilli isolates obtained from Argentinian kefir grains.

In the present study we report for the first time the presence of S-layer proteins in Lactobacillus kefir and Lactobacillus parakefir isolated from kefir grains. Soluble whole-cell protein profile obtained either by mechanical disruption (X-press) or by a combined treatment with lysozyme and SDS on whole cells, showed a significant band of apparent molecular mass of 66–71 kDa as measured by SDS–PAGE. The intensity of this band was considerably reduced when cells were treated with 5 M-LiCl. The above mentioned proteins were recovered in the LiCl extracts. After dialysis and concentration, the proteins extracted were able to reassemble in a regular array. Negative staining of these protein preparations were analysed by transmission electron microscopy and a paracrystalline arrangement was seen. Thin sections of bacteria analysed by transmission electron micrographs showed an outermost layer over the bacterial cell wall, that was lost after the LiCl treatment. The production of this surface structure under different culture conditions was also evaluated. Finally, the relationship between the presence of S-layer proteins and surface properties (e.g. adhesion to Caco-2 cells, autoaggregation, and hemagglutination) was investigated.

A survey was conducted for identification of human group C rotaviruses in stool specimens taken from children suffering diarrhea in suburban Buenos Aires regions. Among 90 true negative group A samples as defined by ELISA, RT‐PCR and PAGE, five were positive by group C specific RT‐PCR (VP7 and VP6 genes) and three of these samples exhibited the characteristic 4‐3‐2‐2 dsRNA pattern of group C rotavirus. These results were further confirmed by electron microscopy and by ELISA for detection of group C VP6 specific antigens. Sequence analysis of the VP7 gene from one of these isolates revealed a 97.3–98.6% nucleotide identity and up to 99.1% protein homology with human group C rotavirus strains found scattered throughout the last ten years in other countries. Conversely, similar analysis performed with porcine strains showed a much lower homology degree both at the nucleotide (75.5% nucleotide identity) and amino acid level (85.5% protein homology). Detection of group C rotavirus in children with acute diarrhea in Argentina extends the identification range of this agent in the region and is consistent with previous reported data that demonstrate a global distribution of this virus. J. Med. Virol. 62:199–207, 2000. © 2000 Wiley‐Liss, Inc.