Date Published: May 17, 2018
Publisher: Springer Berlin Heidelberg
Author(s): Seung-Min Hong, Hyuk-Joon Kwon, Se-Joon Park, Won-Jin Seong, Ilhwan Kim, Jae-Hong Kim.
The yeast strain SJP-SNU was investigated as a probiotic and was characterized with respect to growth temperature, bile salt resistance, hydrogen sulfide reducing activity, intestinal survival ability and chicken embryo pathogenicity. In addition, we determined the complete genomic and mitochondrial sequences of SJP-SNU and conducted comparative genomics analyses. SJP-SNU grew rapidly at 37 °C and formed colonies on MacConkey agar containing bile salt. SJP-SNU reduced hydrogen sulfide produced by Salmonella serotype Enteritidis and, after being fed to 4-week-old chickens, could be isolated from cecal feces. SJP-SNU did not cause mortality in 10-day-old chicken embryos. From 13 initial contigs, 11 were finally assembled and represented 10 chromosomal sequences and 1 mitochondrial DNA sequence. Comparative genomic analyses revealed that SJP-SNU was a strain of Pichia kudriavzevii. Although SJP-SNU possesses pathogenicity-related genes, they showed very low amino acid sequence identities to those of Candida albicans. Furthermore, SJP-SNU possessed useful genes, such as phytases and cellulase. Thus, SJP-SNU is a useful yeast possessing the basic traits of a probiotic, and further studies to demonstrate its efficacy as a probiotic in the future may be warranted.
Many yeasts are present in fermented materials, feces and various environmental sources, a number of which have been used in the production of fermented foods, wine and biofuels. Pichia pastoris has been attempted to be used for single cell protein as animal feed additive, while Saccharomyces cerevisiae has been used as a probiotic for farm animals (Ahmad et al. 2014; Chaucheyras-Durand and Fonty 2001). Saccharomyces boulardii has been used as a probiotic in humans and farm animals due to its antibacterial and anti-diarrheal activities (Baum et al. 2002; Kelesidis and Pothoulakis 2012). Compared with S. cerevisiae, S. boulardii grows at body temperature and may be the preferred choice for use as a probiotic in animals. Probiotics were defined as live microorganisms which confer a health benefit on the host and include bacteria, Lactobacillus, Bifidobacterium etc. and yeasts (Ref. FAO/WHO. Health and nutritional properties of probiotics in food including powder milk with live lactic acid bacteria. Córdoba: FAO/WHO; 2001).
According to the comparative genomics study SJP was identified as P. kudriavzevii. P. kudriavzevii has been isolated from fermented foods and fruit juices and is known as Issatchenkia orientalis and is an anamorph of C. krusei (Arias et al. 2002; Carlotti et al. 1996; Chanprasartsuk et al. 2010; Meroth et al. 2003; Mugula et al. 2003; Zott et al. 2010). P. kudriavzevii is heterothallic but is known to be fertile with P. membranaefaciens, P. scutulata, Candida lambica, C. diversa, C. ingens, C. silvae, C. valida, C. vini, C. norvegensis, or Torulopsis inconspicua (Kurtzman and Smiley 1976).