A traditional Sudanese fermented camel's milk product, Gariss, as a habitat of Streptococcus infantarius subsp. infantarius

Abstract

Samples of the traditional Sudanese fermented camel's milk product Gariss representing 9 different regions in Sudan were microbiologically characterized using an integrated approach including phenotypic and genotypic methods. Lactic acid bacteria [log(CFU/g) = 7.76–8.66] and yeasts [log(CFU/g) = 6.05–7.79] were detected in high numbers. A total of 180 LAB isolates were identified of which 123 isolates were found to belong to the Streptococcus bovis group. Thirteen representative isolates were characterized by PCR amplification and sequencing of the housekeeping genes rpoB and sodA and the streptococcal glucosyltransferase gene ( gtf). All thirteen isolates were identified as Streptococcus infantarius subsp. infantarius, a potential human pathogen. The gene encoding the virulence determinant gtf was detected in 10 of the 13 tested strains. The same isolates were able to survive exposure to 0.3% (w/v) oxgall for 4 h and pH=2.7 for 1--4 h. Also Lactobacillus fermentum were detected in high numbers, whereas Enterococcus faecium and Lactobacillus helveticus were detected more occasionally. The yeast microflora in all Gariss samples consisted of Kluyveromyces marxianus and Issatchenkia orientalis with the former being predominant in 7 out of 9 samples.