Surface microbial consortia from Livarot, a French smear-ripened cheese

Abstract

The surface microflora (902 isolates) of Livarot cheeses from three dairies was investigated during ripening. Yeasts were mainly identified by Fourier transform infrared spectroscopy. Geotrichum candidum was the dominating yeast among 10 species. Bacteria were identified using Biotype 100 strips, dereplicated by repetitive extragenic palindromic PCR (rep-PCR); 156 representative strains were identified by either BOX-PCR or (GTG)(5)-PCR, and when appropriate by 16S rDNA sequencing and SDS-PAGE analysis. Gram-positive bacteria accounted for 65% of the isolates and were mainly assigned to the genera Arthrobacter , Brevibacterium , Corynebacterium , and Staphylococcus . New taxa related to the genera Agrococcus and Leucobacter were found. Yeast and Gram-positive bacteria strains deliberately added as smearing agents were sometimes undetected during ripening. Thirty-two percent of the isolates were Gram-negative bacteria, which showed a high level of diversity and mainly included members of the genera Alcaligenes , Hafnia , Proteus , Pseudomonas , and Psychrobacter . Whatever the milk used (pasteurized or unpasteurized), similar levels of biodiversity were observed in the three dairies, all of which had efficient cleaning procedures and good manufacturing practices. It appears that some of the Gram-negative bacteria identified should now be regarded as potentially useful in some cheese technologies. The assessment of their positive versus negative role should be objectively examined.

Quantitative and qualitative microbial analysis of raw milk reveals substantial diversity influenced by herd management practices

“…were detected mainly in winter samples. This is a psychrotrophic genus also described in cheese (Coton et al, 2012;Larpin-Laborde et al, 2011;Maoz, Mayr, & Scherer, 2003). Gram-negative bacteria exhibited greater diversity in spring milk than in winter milk.…”

Yarrowia lipolytica: Safety assessment of an oleaginous yeast with a great industrial potential

“…Also growth curves do not provide a clear-cut picture: while in some studies, counts of Y. lipolytica increased toward the end of cheese ripening (which might indicate a risk for overgrowth; Brocklehurst & Lund, 1985;Larpin-Laborde et al, 2011;Welthagen & Viljoen, 1998), both total yeast counts and Y. lipolytica counts stayed constant or even decreased in other studies (Ferreira & Viljoen, 2003;van den Tempel & Jakobsen, 1998).…”

“…Therefore, its occurrence in cheese must be due to either its presence in milk or through contamination of equipment, bodily surfaces of operators, or aprons in the cheese-making environment (Larpin-Laborde et al, 2011;Welthagen & Viljoen, 1998). Despite the fact that Y. lipolytica is not added deliberately, it has been reported frequently to be among the top-three most prevalent yeast species in cheese (e.g.…”

“…Despite the fact that Y. lipolytica is not added deliberately, it has been reported frequently to be among the top-three most prevalent yeast species in cheese (e.g. Larpin et al, 2006;Larpin-Laborde et al, 2011;Monnet et al, 2010;Roostita & Fleet, 1996;Welthagen & Viljoen, 1998), and even to outcompete other yeast species (Lanciotti et al, 2005). Because Y. lipolytica is reported to be strictly aerobic (Barth & Gaillardin, 1997;Fickers et al, 2005), it has mostly been identified in the surface microflora, or in the interior of blue-veined and cottage cheese where oxygen is also available (see Supplementary Table 1).…”

Genome Sequence of Staphylococcus saprophyticus DPC5671, a Strain Isolated from Cheddar Cheese

“…Strains belonging to the Staphylococcus genus are commonly identified in soft cheese varieties made from cow, ewe, or goat milk, and together with Brevibacterium , Corynebacterium , and Microbacterium , Staphylococcus is considered the most important genus making up the microbiota of the cheese surface (1). S. saprophyticus is a species frequently detected on the surface of smear-ripened cheese and other fermented foods (2–4). Here, we present the draft genome sequence of S. saprophyticus DPC5671, which will allow a full safety assessment and further analysis on its role in cheese ripening.…”