Isolation of Hexavalent chromium tolerant fungal species from urban vegetable farm soil and effluent waste in Addis Ababa& Rift valley, Ethiopia

Abstract

Hexavalent chromium is resistant to degradation and sever toxic substance to environment and community health.Physico chemical treatment methods are demanding high cost, used large quantities of chemicals & energy, release large amount of secondary toxic degradants. Mycoremediation is an eco-friendly alternative treatment method. The main objective of this research is to isolate and characterize chrome (VI) tolerant yeast from farm soil & industry e uent for mycoremedation role. The screening and isolation of yeast was carried out on potato dextrose agar media.Solid agar and broth assay test for yeast tolerance on hexavalent chromium at different concentration, temperature and pH was evaluated. Yeast species was identi ed biochemically using Biolog Microstation depending on carbon utilization and chemical sensitivity test. The result revealed that 11 yeast species was identi ed from e uent waste and farm soil based on their probability >75% and similarity index >0.5 as well as their hexavalent chromium tolerance ability up to 2500ppm. These are Yarrowia lipolytica (100%,0.7) Cryptococcus luteolus(100%,0.64), Rhodotorula aurantiaca A (100%,0.62), Ustilago maydis (100%,0.58) Trichosporon beigelii B (100%,0.51),Cryptococcus terreus A (100%,0.62), Zygosaccharomyces bailii (98%,0.65), Nadsoniafulvenscens (90%,0.62), Schizoblastosporon starkeyi henricii (89%,0.56), Endomycopsis vivi (84%,0.62), Rhodotorula pustula (Sim 0.59). Two yeast species Yarrowia lipolytica and Nadsonia fulvenscens show the highest mean Optical density (OD) measure (0.953+0.43), (0.96+0.400) respectively at pH4 &25OC. Cr (VI)-tolerance ability of these yeast strains used after further HPLC analysis& molecular characterization in the development of chromium-bioremediation technologies provide an alternative method for chromium sequestration.

The role and mechanisms of microbes in dichlorodiphenyltrichloroethane (DDT) and its residues bioremediation

“…DDT-microbial accumulation happens when the concentration in the biosphere is significantly higher than in the surrounding area. As a result of microbial accumulation, environmental pollutants harm the microbes [ 99 , 100 ]. The lipophilic nature of DDT pesticides makes them more easily absorbed in cells due to the lipophilic components on the cell membrane [101] .…”

The Identification of a Strain for the Biological Purification of Soy Molasses to Produce Functional Soy Oligosaccharides and Optimize Purification Conditions

“…A crucial concept for differentiating and classifying microbial species according to their capacity to metabolize various carbon sources is that different microorganisms often have distinct carbon source metabolism profiles [29][30][31][32]. With this knowledge, different microorganisms can be used for the pre-treatment of soy molasses to break down sucrose and utilize it through the microorganisms' specific carbon source metabolism while preserving FSO such as raffinose and stachyose to the greatest extent possible.…”