Purification ofCandida guilliermondiiandPichia ohmerikiller toxin as an active agent againstPenicillium expansum

Abstract

An antifungal assay with cell-free culture supernatant of Pichia ohmeri 158 and Candida guilliermondii P3 was tested against Penicillium expansum strain #2 at 25 degrees C by measuring hyphal length and percentage conidia germination. C. guilliermondii was more effective against P. expansum conidia germination (58.15% inhibition), while P. ohmeri showed higher inhibition of mycelial growth (66.17%), indicating a probable mechanism associated with killer activity. This killer toxin (molecular mass <3 kDa) was partially purified by normal phase HPLC, using TSKgel Amide-80 analytical and preparative columns. Compared with crude extract, the killer toxin eluted from the post analytical column significantly inhibited P. expansum:% inhibition rose from 42.16 to 90.93% (C. guilliermondii) and 39.32 to 91.12% (P. ohmeri) (p < 0.05). The one-step purification process was adequate in isolating killer toxin from culture supernatant and also increased anti-Penicillium activity.

Preliminary prospection of the yeast biodiversity on apple and pear surfaces from Northern Italy orchards

“…This species has frequently been proposed as a biocontrol agent on fruit (Droby et al 1997;Petersson and Schnurer 1995;Richards et al 2004;Xu et al 2008) and as a source of a micotoxin to control P. expansum (Coelho et al 2009). …”

Phenotypic and molecular diversity of Meyerozyma guilliermondii strains isolated from food and other environmental niches, hints for an incipient speciation

“…The ability of M. guilliermondii to contrast Penicillium expansum and other fruit spoiling molds has been exploited by including this yeast in several study of non-chemical post-harvest control (Droby et al, 1997;Richards et al, 2004;Zhao et al, 2009Zhao et al, , 2010 and by proposing its toxin to protect fruit (Coelho et al, 2009). The antimicrobial activity displayed by M. guilliermondii cells has been also proposed to protect wheat (Petersson and Schnurer, 1995), bread (Coda et al, 2013) and olives (Hernandez et al, 2008).…”

Killer toxin from a novel killer yeastPichia kudriavzeviiRY55 with idiosyncratic antibacterial activity

“…Elution was accomplished by increasing concentrations of NaCl (0.25–1.0 M). The fractions collected were examined for killer activity and protein content .…”

“…Numerous reports are available where‐in antagonistic action of killer toxins is reported against same or closely related yeast/fungal genera ; however, quite rare reports are available on antibacterial activity of killer toxins . Killer phenomenon has been reported among several species of Pichia which display killer activity against pathogenic yeast or fungi .…”