Isolation and identification of yeasts along wastewater treatment lines at Zagazig plant

Document Type : Original Article


Agriculture Microbiology Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt


Phenol is one of the most common pollutants in many kinds of industrial wastewater, some of which are in high heavy metals contents, resulting in more difficulties of biodegradation. This study aims to characterize the presence of yeasts along the processes in wastewater treatment plant (WTP) at Zagazig City. The most predominant species of yeast in wastewater were Candida parasopilis (n=5), Candida krusei (n=8) Cryptococcus neoformans (n=3), Geotrichum candidum. (n=9) and Saccharomyces cerevisiae (n=5). The distribution of these species in wastewater was 17, 27, 10, 30 and 17%, respectively. Geotrichum candidumand Candida krusei were the most common fungal species isolated and were present in a significant proportion in wastewaters. However, between the 30 yeast isolates, only 11 isolates (3: C. parasopilis,3: C. krusei, 3: G. candidum and 2: S. cerevisiae) showed a high growth rate at phenol concentration reaching up to 20 mg/l. Also, all strains could grow at high concentration of zinc sulphate, reaching up to 12 mg/l. The untreated of C. parasopilis and treatment with 0.7 mg/l phenol concentration had a normal morphology with no cell morphological changes by scanning electron microscope. The results indicated that this strain is a good candidate to be used in further studies and different applications in the field of treated wastewater form phenol and heavy metal biosorption.


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