Conference Book of Abstracts - Taita Taveta University College

while from Kisii had the lowest cyanide concentration (43.27 mg/kg). Nairobi and Thika hadmoderately high concentration of 66.00 and 54.84 mg HCN equivalents/kg cassava fresh weight.During the period of study, two families, a family of six(6) and of seven(7) from Makueni andKathonzweni districts in Eastern Province were effected after consuming raw and cookedcassava in the month of September 2011, where two (2) children aged four(4) and five(5) diedand other family members were taken ill to Makueni District Hospital. The cyanide levels in thecassava were high, and ranged between 46.03 and 53.37 mg HCN equivalents/kg fresh cassavaweight. Cassava from all the regions registered high levels of cyanide compared to therecommended accepted level of 10 mg/kg per body weight by WHO. There is need for publicawareness on processing of cassava before consumption.Impact of Prolonged Application of Xenobiotics on Indigenous Microbes in SoilAnastasia Ngigi 1 , David Ndalut 2 , Hamadi Boga 3 , Zachary Getenga 21 Masinde Muliro University of Science & technology, P.O. Box Box 190 – 50100, Kakamega.2 Chepkoilel University College, 3 Jomo Kenyatta University of Agriculture and TechnologyEmail: anjokingugi@yahoo.comThe environmental fate of herbicides is a matter of major concern given that only a small fractionof the chemicals reach the target organisms. This leads to potential negative impacts of residualherbicides on human, animal and crop health. Herbicides affect microbes indirectly, causingphysiological changes, increased enzymatic production or, when applied in high doses, death ofsusceptible groups of microorganisms. In most cases they lead to the indigenous microbesgetting adapted to the xenobiotics by utilizing the same for energy and growth. In soil systems,biodegradation is a fundamental attenuation process for pesticides. This study reports themicrobial adaptation to atrazine and diuron herbicides in soils. Atrazine (6-chloro-N 2 -ethyl-N 4 -isopropyl-1,3,5-triazine-2,4-diamine) and diuon [N-(3,4-dichlorophenyl)-N,N-dimethylurea]herbicides are extensively and frequently applied in sugarcane-cultivated soils. Soils have beenscreened for the rapid degradation of the xenobiotics by evolution of 14 CO 2 from the utilizationof the 14 C-labelled compounds, by measuring bacterial cell density through optical densitymeasurements and by measuring the residual levels of the xenobiotic at different time intervals.For instance, two model compounds (diuron and atrazine) have been extensively studied withsubsequent isolation and characterization of the key microorganisms which have been adapted tothe utilization of the xenobiotics for energy and growth. In this study, liquid culture experimentswith atrazine and diuron led to isolation of different bacterial strains that could degrade the twoherbicides. This confirms the adaptation of indigenous microbes to herbicides after repeatedapplications.Key words: atrazine, diuron, biodegradation, adaptation, liquid culturesThe Role of Horticultural Association of Kenya (HAK) in Conservation and Utilization ofBiodiversity in KenyaJohn Mwibanda Wesonga