Culture-Dependent and -Independent Methods To Investigate the Microbial Ecology of Italian Fermented Sausages

Abstract

In this study, the microbial ecology of three naturally fermented sausages produced in northeast Italy was studied by culture-dependent and -independent methods. By plating analysis, the predominance of lactic acid bacteria populations was pointed out, as well as the importance of coagulase-negative cocci. Also in the case of one fermentation, the fecal enterocci reached significant counts, highlighting their contribution to the particular transformation process. Yeast counts were higher than the detection limit (>100 CFU/g) in only one fermented sausage. Analysis of the denaturing gradient gel electrophoresis (DGGE) patterns and sequencing of the bands allowed profiling of the microbial populations present in the sausages during fermentation. The bacterial ecology was mainly characterized by the stable presence of Lactobacillus curvatus and Lactobacillus sakei, but Lactobacillus paracasei was also repeatedly detected. An important piece of evidence was the presence of Lactococcus garvieae, which clearly contributed in two fermentations. Several species of Staphylococcus were also detected. Regarding other bacterial groups, Bacillus sp., Ruminococcus sp., and Macrococcus caseolyticus were also identified at the beginning of the transformations. In addition, yeast species belonging to Debaryomyces hansenii, several Candida species, and Willopsis saturnus were observed in the DGGE gels. Finally, cluster analysis of the bacterial and yeast DGGE profiles highlighted the uniqueness of the fermentation processes studied.

Microbial Community Structure and Dynamics of Dark Fire-Cured Tobacco Fermentation

“…Noteworthy is the specificity of the association between D. hansenii and several lactic acid and coryneform bacteria, including those we isolated from fermenting tobacco. These microbial consortia are typical of certain fermenting substrates that are characterized by a low C/N ratio, such as ripening cheeses (2,4,10,31,36,43,61), fresh sausages (7,47), vegetables (35), and algae (57). An association between D. hansenii and P. pentosaceus, revealed for tobacco samples (Tables 4 and 5), has previously been described for sorghum fermentation (35), and the same yeast has been isolated from the surface microflora of many brick cheeses in association with several coryneform bacteria, including C. ammoniagenes (58).…”

Analysis of Microbial Diversity in Makgeolli Fermentation Using PCR-DGGE

“…DGGE분석에서 16S 또는 28S rRNA gene의 크기는 동일 하나 서열이 다른 PCR산물을 분리할 수 있었으며 이 기술은 토양 [28], 해양 [2], 곤충 [27], sludge [35] 등 다양한 환경에서 미생물의 dynamics 연구를 위해 광범위하게 적용되어 왔다. 또한 이러한 방법은 누룩 [17], 김치 [3], 와인 [5,22], sausage [26], sourdough [24], coffee [23], 치즈 [6] (Fig. 3A), 각 band의 DNA로부터 염기서열을 결정하여 NCBI의 BLAST search를 통하여 similarity가 가장 높은 종으로 동정하였다 (Fig.…”

Food Microbiota Diversity

“…Among the advantages of AFLPs analysis, is that the process is amenable to full high speed automation and precise analysis, which allows for the simultaneous comparison of hundreds of colonies isolated from the same or different sources permitting an estimation of the microbial biodiversity. The most frequently isolated LAB from fermented sausages are Lactobacillus sakei, L. curvatus, and L. plantarum, while among the CNC it is Staphylococcus xylosus that is most usually found (Cocolin et al, 2001a;Rossi et al, 2001;Aymerich et al, 2003;Cocolin et al, 2004;Rantsiou et al, 2005b). Concerning the typology of sausages that have been analysed, several reports only consider the microbiota isolated from "Salame friulano" (Cocolin et al, 2001a;Cocolin et al, 2001b;Comi et al, 2005;Rantsiou et al, 2005a;Rantsiou et al, 2005b;Urso et al, 2006).…”

“…The most frequently isolated LAB from fermented sausages are Lactobacillus sakei, L. curvatus, and L. plantarum, while among the CNC it is Staphylococcus xylosus that is most usually found (Cocolin et al, 2001a;Rossi et al, 2001;Aymerich et al, 2003;Cocolin et al, 2004;Rantsiou et al, 2005b). Concerning the typology of sausages that have been analysed, several reports only consider the microbiota isolated from "Salame friulano" (Cocolin et al, 2001a;Cocolin et al, 2001b;Comi et al, 2005;Rantsiou et al, 2005a;Rantsiou et al, 2005b;Urso et al, 2006). In the present study we have used fluorescent AFLP to analyse the genetic variability of cultured bacteria isolated from populations present in traditional North Italian fermented 'salami' in order to: (i) define the biodiversity of cultured bacteria involved in traditional meat fermentation of high quality products produced without using starter cultures; (ii) define the utility of AFLP in characterising, at strain level, the indigenous sausage microflora; (iii) collect the different isolates and identify strain specific electropherograms usable as markers for traceability of the product.…”