title: Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions.
abstract: We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria.
authors.affiliation: Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
authors.forename: Eliska
authors.initials: E
authors.lastname: Benadé
authors.affiliation: Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.|Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.
authors.forename: Wendy
authors.initials: W
authors.lastname: Stone
authors.affiliation: Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.|Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, South Africa.
authors.forename: Marnel
authors.initials: M
authors.lastname: Mouton
authors.affiliation: Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Postma
authors.affiliation: Virtual Consulting Engineers (Pty.) Ltd., Groenkloof, South Africa.
authors.forename: Jac
authors.initials: J
authors.lastname: Wilsenach
authors.affiliation: Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa. abo@sun.ac.za.
authors.forename: Alfred
authors.initials: A
authors.lastname: Botha
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D000898:Antibiosis; D001419:Bacteria / Q000254:growth & development; D018407:Bacterial Physiological Phenomena; D002176:Candida albicans / Q000254:growth & development / Q000502:physiology*; D018920:Coculture Techniques
keywords: Aerobic; Anaerobic; Bacteria; Candida albicans; Hydrolytic enzymes; Prodigiosin