Characterization of Kazachstania slooffiae, a proposed commensal in the porcine gut

Authors: Summers, Katie; Foster Frey, Juli; ARFKEN, ANN - US Department Of Agriculture (USDA)

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2021
Publication Date: 2/17/2021
Citation: Summers, K.L., Foster Frey, J.A., Arfken, A.M. 2021. Characterization of Kazachstania slooffiae, a proposed commensal in the porcine gut. The Journal of Fungi. 7(2):146. https://doi.org/10.3390/jof7020146.
DOI: https://doi.org/10.3390/jof7020146

Interpretive Summary: Kazachstania slooffiae is the most dominant fungus found in the gastrointestinal tract and feces of piglets after weaning. Despite previous studies implicating its ability to benefit the gut and overall health of pigs, little is known about its growth requirements, antimicrobial susceptibility, and biofilm growth characteristics. Due to its potential role in piglet health and growth, scientists at the Agricultural Research Service, Beltsville, Maryland analyzed the genome of K. slooffiae to create an accurate phylogenetic tree and documented the ability of this potential commensal to grow as a biofilm in the laboratory. These studies demonstrate a lack of antimicrobial resistance in this species and documents the ability of gut bacteria to alter fungal biofilm density in vitro. These results are an important step in defining the role and interactions of K. slooffiae in the porcine gut environment.

Technical Abstract: The importance of fungal species in the gut microbial milieu has recently been recognized, but much remains to be learned about these fungal commensals and transients. Kazachstania slooffiae is a fungus commonly isolated from the gastrointestinal tract and feces of post-weaning pigs. Studies have implicated its ability to positively alter piglet gut health through potential symbioses with beneficial bacteria, including Lactobacillus and Prevotella, in providing amino acids as an energy source for microbial and piglet growth, and has been found to be positively correlated with short chain fatty acids in the piglet gut. However, basic mycological information remains limited on this important porcine fungus, limiting in vitro studies in a laboratory setting. In this study, we characterized the growth parameters, biofilm formation ability, susceptibility to antimicrobials, and the genetic relatedness of K. slooffiae to other fungal isolates. Optimal fungal growth was found using Yeast Potato Dextrose media at 37°C with shaking at 200 rpm. K. slooffiae did not demonstrate any antifungal resistance against multiple classes of antifungal drugs (azoles, echinocandins, polyenes, or pyrimidine analogues) and was able to grow as a yeast or as infrequently differentiated pseudohyphae. K. slooffiae produced biofilms that became more complex in the presence of Lactobacillus acidophilus supernatant, suggesting its ability to interact positively with this beneficial bacterium in the gut, while biofilms produced in the presence of Enterococcus faecalis supernatant were significantly less dense, suggesting an antagonistic interaction. This study characterizes the in vitro growth conditions that are optimal for further studies of K. slooffiae, demonstrates its low resistance to antifungals, and its ability to create complex biofilms in the presence of bacterial commensals. These results are an important step in defining the role and interactions of K. slooffiae in the porcine gut environment.