Airborne Yeast Isolates as Biocontaminants at Two Different Indoor Environments in Cairo

Abstract

This study was conducted during the period of November 2000 to October 2001 to trap, enumerate and identify the different airborne yeast isolates in a variety of microhabitats of indoor environments in two different localities in Cairo (Opera house & Police prison rooms). The settle plate method was used on different media. A total of 10 genera and 25 species were trapped from all exposures. The total yeast catched (in cfu) obtained from all exposures during the four seasons were 860 colonies. Police prison rooms count recorded the highest count (640 cfu) than Opera house (256 cfu). The genus Candida was the dominate genus representing 74.4% of the total count. Highest count was recorded in autumn (546 cfu) and the lowest in spring (59 cfu). The isolated yeasts were tested for their ability to produce mycotoxin by studying their effects on Grampositive bacteria (B. subtilis), Gram-negative bacteria (E. coli), yeast (C. albicans) and mold fungi (A. niger). Many isolates produced antimicrobial toxins in variable amounts Candida steatolytic and Rhodotorula glutinis have antagonistic activity against the four tested human pathogens. The pathogenic potentialities of some selected Candida species were studied. They were manifested by growth at 370C, production of proteolytic and lipolytic enzymes and blood haemolysis. Enzyme assay for the proteolytic enzymes (acidic, neutral & alkaline proteases) were studied. The different Candida species selected yielded variable amounts of proteolytic enzymes and acid proteases were produced in relatively high amounts. Candida albicans recorded the maximum yield of acid protease. Antifungal sensitivity test of selected Candida species revealed that they were sensitive to Nystatin and varied towards the other antifungal agents.