Commercial Ripening Starter Microorganisms Inoculated into Cheese Milk Do Not Successfully Establish Themselves in the Resident Microbial Ripening Consortia of a South German Red Smear Cheese

Abstract

Production of smear-ripened cheese critically depends on the surface growth of multispecies microbial consortia comprising bacteria and yeasts. These microorganisms often originate from the cheese-making facility and, over many years, have developed into rather stable, dairy-specific associations. While commercial smear starters are frequently used, it is unclear to what degree these are able to establish successfully within the resident microbial consortia. Thus, the fate of the smear starters of a German Limburger cheese subjected to the "old-young" smearing technique was investigated during ripening. The cheese milk was supplemented with a commercial smear starter culture containing Debaryomyces hansenii, Galactomyces geotrichum, Arthrobacter arilaitensis, and Brevibacterium aurantiacum. Additionally, the cheese surface was inoculated with an extremely stable in-house microbial consortium. A total of 1,114 yeast and 1,201 bacterial isolates were identified and differentiated by Fourier transform infrared spectroscopy. Furthermore, mitochondrial DNA restriction fragment length polymorphism, random amplified polymorphic DNA, repetitive PCR, and pulsed field gel electrophoresis analyses were used to type selected isolates below the species level. The D. hansenii starter strain was primarily found early in the ripening process. The G. geotrichum starter strain in particular established itself after relocation to a new ripening room. Otherwise, it occurred at low frequencies. The bacterial smear starters could not be reisolated from the cheese surface at all. It is concluded that none of the smear starter strains were able to compete significantly and in a stable fashion against the resident microbial consortia, a result which might have been linked to the method of application. This finding raises the issue of whether addition of starter microorganisms during production of this type of cheese is actually necessary.

Bavariicoccus seileri gen. nov., sp. nov., isolated from the surface and smear water of German red smear soft cheese

“…FT-IR spectroscopy for typing these lactic acid bacteria below the species level is demonstrated by our data, as has already been done for coryneform bacteria by Goerges et al (2008).…”

Micro-eukaryotic diversity of the human distal gut microbiota: qualitative assessment using culture-dependent and -independent analysis of faeces

“…Both Candida sp and, in particular, Saccharomyces sp are routinely used in the brewing and baking industry; Galactomyces sp are routinely found in cheese microbial consortia where they are used in starter cultures (Goerges et al, 2008); and Galactomyces geotrichum has also been identified as an agent in soft drinks spoilage (Ancasi et al, 2006). As such, when fermented foods and beverages or food containing eukaryotic species are consumed on a continuous basis, they provide ready inocula for the host.…”

Galactomyces geotrichum – moulds from dairy products with high biotechnological potential

“…However, two morphologically different types of this mould were found in the samples. One colony had a turquoise-to blue-coloured surface and was present in all batches, and the other had a light green and fluffy appearance and was present in half of the batches (Goerges et al, 2008).…”

“…The most frequently described sources of G. geotrichum isolation are summarized in Figure 1. The majority of publications concerning the G. geotrichum mould are related to its presence in the dairy industry, especially in cheeses (Binetti et al, 2013;Chebeňová-Turcovská et al, 2011;Flores--Magallón et al, 2011;Goerges et al, 2008;Majcher et al, 2014;Sadecka et al, 2016;. This mould belongs to secondary microflora and is able to survive in ripening cheese where the pH is low and where water activity and salt concentration are high (Binetti et al, 2013).…”

“…The G. geotrichum mould was also predominant in German Limburger cheese (Goerges et al, 2008). For the production of this cheese, pasteurized milk was used, as well as a thermophilic lactic acid starter culture.…”