Comparative analysis of two antifungal Lactobacillus plantarum isolates and their application as bioprotectants in refrigerated foods

Abstract

Aims: To compare the technological robustness of two antifungal Lactobacillus plantarum isolates and to assess their ability to inhibit growth of the spoilage yeast Rhodotorula mucilaginosa in two different refrigerated foods. Methods and Results: The effects of freeze-drying, thermal treatments and varying salt concentrations on the viability of two antifungal lactic acid bacteria (LAB) were examined. Antifungal compound(s) contained in the supernatant of both isolates were compared to commercially available food preservatives. Both isolates were used as dairy starter adjuncts in yoghurt and inoculants in orange juice to determine the antiyeast activity towards R. mucilaginosa. Yeast growth was retarded by the tested isolates in both food settings with one of the isolates, Lact. plantarum 16, being the most potent inhibitor. Conclusions: Both lactobacilli exhibited considerable robustness to withstand processing treatments commonly encountered in a food industrial setting. The isolates were shown to possess potent antifungal activity in both in vivo and in vitro food models. Significance and Impact of the Study: The studied antifungal lactobacilli may represent safer and consumer-friendly alternatives to the use of chemical preservatives. This is the first report of antifungal Lact. plantarum exerting protective potential in yoghurt and orange juice.

The Value of Patch-Choice Copying in Fruit Flies

“…Adults and larvae inoculate fruit with yeast and larval activity promotes the growth of certain yeast species [57]–[59]. While some of the positive effects of larvae on yeast can be modulated through churning of the substrate, the larval gut bacteria also produce antifungals, which could selectively suppress mold and thus enhance the growth of the preferred yeast food [31], [60]–[62]. Intriguingly, adult and larval fruit fly attraction to food inhabited by larvae is mediated by volatiles emitted from gut bacteria [31].…”

Social attraction mediated by fruit flies' microbiome

“…Mould can cause high rates of mortality among fruit fly larvae, and groups of larvae can suppress mould growth as well as enhance the growth of certain yeast species (Rohlfs et al, 2005;Stamps et al, 2012). Intriguingly, both species of Lactobacillus we have studied produce compounds that suppress fungal and bacterial growth (Ruiz-Barba et al, 1994;Laitila et al, 2002;Schnürer and Magnusson, 2005;Mauch et al, 2010;Crowley et al, 2012). The fruit fly microbiome may thus help larvae control the species composition of fungi and bacteria on their fruit substrates.…”

Transcriptomic and morphological profiling of Aspergillus fumigatus Af293 in response to antifungal activity produced by Lactobacillus plantarum 16

“…plantarum 16 inhibited the growth of the spoilage yeast Rhodotorula mucilaginosa (Crowley et al, 2012b). Here we assessed the effects of adding varying amounts of 206 cCFS from Lb.…”

“…plantarum 16 is a malt-production, steep water isolate possessing broad-spectrum antifungal activities towards a variety of food spoilage fungi (Crowley et al, 2012a). It has been successfully used as a biopreservative to arrest growth of Rhodotorula mucilaginosa in both yoghurt and orange juice models, in addition to displaying features of technological robustness (Crowley et al, 2012b). The availability of the whole genome sequence of A. fumigatus Af293 makes it a suitable candidate to study its transcriptomic response to the antifungal activity produced by certain LAB.…”

“…Lb. plantarum 16 was previously shown to exhibit antifungal activity towards A. fumigatus (Crowley et al, 2012b), and the current study examines the effects of cCFS from Lb. plantarum 16 on the growth of two foodassociated spoilage moulds, A. fumigatus and R. stolonifer, by microscopic analysis at different stages in the growth cycle.…”