Debaryomyces hansenii Strains Isolated From Danish Cheese Brines Act as Biocontrol Agents to Inhibit Germination and Growth of Contaminating Molds

Abstract

The antagonistic activities of native Debaryomyces hansenii strains isolated from Danish cheese brines were evaluated against contaminating molds in the dairy industry. Determination of chromosome polymorphism by use of pulsed-field gel electrophoresis (PFGE) revealed a huge genetic heterogeneity among the D. hansenii strains, which was reflected in intra-species variation at the phenotypic level. 11 D. hansenii strains were tested for their ability to inhibit germination and growth of contaminating molds, frequently occurring at Danish dairies, i.e., Cladosporium inversicolor, Cladosporium sinuosum, Fusarium avenaceum, Mucor racemosus, and Penicillium roqueforti. Especially the germination of C. inversicolor and P. roqueforti was significantly inhibited by cell-free supernatants of all D. hansenii strains. The underlying factors behind the inhibitory effects of the D. hansenii cell-free supernatants were investigated. Based on dynamic headspace sampling followed by gas chromatography-mass spectrometry (DHS-GC-MS), 71 volatile compounds (VOCs) produced by the D. hansenii strains were identified, including 6 acids, 22 alcohols, 15 aldehydes, 3 benzene derivatives, 8 esters, 3 heterocyclic compounds, 12 ketones, and 2 phenols. Among the 71 identified VOCs, inhibition of germination of C. inversicolor correlated strongly with three VOCs, i.e., 3-methylbutanoic acid, 2-pentanone as well as acetic acid. For P. roqueforti, two VOCs correlated with inhibition of germination, i.e., acetone and 2-phenylethanol, of which the latter also correlated strongly with inhibition of mycelium growth. Low half-maximal inhibitory concentrations (IC50) were especially observed for 3-methylbutanoic acid, i.e., 6.32–9.53 × 10–5 and 2.00–2.67 × 10–4 mol/L for C. inversicolor and P. roqueforti, respectively. For 2-phenylethanol, a well-known quorum sensing molecule, the IC50 was 1.99–7.49 × 10–3 and 1.73–3.45 × 10–3 mol/L for C. inversicolor and P. roqueforti, respectively. For acetic acid, the IC50 was 1.35–2.47 × 10–3 and 1.19–2.80 × 10–3 mol/L for C. inversicolor and P. roqueforti, respectively. Finally, relative weak inhibition was observed for 2-pentanone and acetone. The current study shows that native strains of D. hansenii isolated from Danish brines have antagonistic effects against specific contaminating molds and points to the development of D. hansenii strains as bioprotective cultures, targeting cheese brines and cheese surfaces.

Exploring Biocontrol of Unwanted Fungi by Autochthonous Debaryomyces hansenii Strains Isolated from Dry Meat Products

“…However, what we observed is a noticeable decrease or even an absence of apparent sporulation in the treated plates. This fact has been previously mentioned in other studies, but as far as we know, and in relation to the use of D. hansenii , neither quantitative data nor images supporting the proposal were provided [ 20 , 26 , 28 , 29 ].…”

“…The latter are specifically associated with inhibition of germination and mycelial growth of Candida and Penicillium species. [ 29 ]. To our knowledge, our research is the first report that specifically shows images of how the diffusible and volatile compounds’ action affects sporulation.…”

Utilization of salt‐rich by‐products from the dairy industry as feedstock for recombinant protein production by Debaryomyces hansenii

“…Consequently, fewer microorganisms can stand the high osmotic pressure or need more time to adapt their metabolism to the high salt amounts, giving D. hansenii the advantage to grow. The second case has been already appointed by several authors who demonstrated that D. hansenii produces a killer toxin (mycocin) only in the presence of NaCl (Huang et al, 2021;Llorente et al, 1997;Marquina et al, 2001;Medina-Córdova et al, 2018). This toxin seems to be effective against different genres of yeast, fungi and bacteria.…”

Perfume Guns: Potential of Yeast Volatile Organic Compounds in the Biological Control of Mycotoxin-Producing Fungi

“…Other yeast species ( Candida maltosa , D. hansenii , I. orientalis , P. occidentalis , M. guilliermondii , M. caribbica , K. marxianus ) have been later tested in vitro against grain-spoiling fungi such as P. citrinum , P. chrysogenum , P. roqueforti , and P. verrucosum [ 66 , 69 , 70 , 106 , 107 ]. In most instances, the biological efficacy of volatile compounds was measured on vegetative growth or spore germination ( Table 1 ).…”

“…Only Alasmar et al [ 70 ] reported a significant reduction (from 31.1 ± 0.54 μg/kg in the control, to 0.12 ± 0.03 μg/kg in the exposed fungus) of OTA released in the medium by P. verrucosum upon exposure to K. marxianus volatiles. The volatile components considered responsible for fungal growth or mycotoxin inhibition were: isoamyl acetate, isoamyl alcohol [ 66 ], 2-methyl-1-propanol, 3-methyl-1-butanol, 2-methyl-1-butanol [ 106 ], 2-phenylethanol [ 69 , 107 ], phenylethyl acetate [ 69 ], nonadecane, eicosane, docosane, heptacosane, hexatriacontane, and tetracosane [ 70 ] acetone [ 107 ], as well as several esters, alcohols, terpenes, ketones, aldehydes, and aromatic hydrocarbons [ 69 ].…”