DETERMINATION OF TOXIGENIC FUNGI AND THEIR ASSOCIATED MYCOTOXINS IN MAIZE FROM MERU COUNTY NAME: REG NO: JOHN NDERITU GATHOGO A22/1803/2010 SUPERVISOR: PROF: R.D NARLA
INTRODUCTION Maize belongs to gramineae family and is adaptable to a wide range of agro-ecological zones. Globally it is ranked third from wheat and rice and dorminates food crops as the main diet for many household families. In Kenya it is grown in large scale in Rift Valley and Western province. In Kenya it is the main staple food for many people and plays an important part in fighting food insecurity. It is consumed daily by many households and contributes over 80% of total cereals consumed and is estimated to contribute 20%of total agricultural production..
PROBLEM STATEMENT AND JUSTIFICATION Maize is prone to mycotoxins attack during pre and post harvest periods due to Fusarium and Aspergillus spp invasion and this has put many individuals in dangers of chronic exposure to mycotoxins in their diet. Kenya has been documented as one of the most severely inflicted country with acute aflatoxicosis Mycotoxins and heat stable and capable of interfering with metabolic processes at very low dosage. Therefore to prevent high risk of causing food insecurity there is need to be well informed on critical control points and measures during handling of cereals to prevent chances of contamination.
OBJECTIVES AND HYPOTHESIS The general objective is the determination of toxigenic fungi and their associated mycotoxins in maize from Meru County Specific objectives are:- To determine which location is more prevalence to toxigenic fungi To determine fumonisins and aflatoxins levels in maize The hypothesis is that there is no difference in mycotoxins levels among the locations
MATERIALS AND METHODS The experiment was done in the university of Nairobi ( CAVS) in the Plant Pathology Lab, it was subjected to a CRD with three replicates per treatment. A total of 30 samples of maize were collected from 10 locations in Meru. 3 samples from each location of about 500gms were randomly taken from the different parts of the bag and pooled together, all the samples comprised of visibly clean maize accepted for consumption. Half of the samples was used for isolation of fungal spp while the other half was used for toxins extraction and analysis
CONT. Samples were ground and made to a dilution factor of 10 ³ for fungal isolation. For further differentiation of Aspergillus spp subculturing was done on Czapeck Dox Ager Sub-culturing of Fusarium spp was done in SNA for sporulation to occur and incubated in the dark. For microscopic characteristics of Aspergillus genus was done by preparing Riddel slides which allowed fungus to sporulate for observations. The genus of Fusarium spp, cello-tape was used which holds the conidia in position which were mounted on the slides for microscopy examination
TOXIN EXTRACTION AND ANALYSIS OF FUMONISINS AND AFLATOXIN Sufficient sample to be tested is ground to fine particles 5g were weighed and 25mls of extraction solvent (70% methanol) was added at the ratio of 1:5 for aflatoxin extraction while 40% methanol for fumonisin was added. Assay was done using ELISA Kit and the OD of each microwell was read and recorded. The O.D were analyzed using logit software and the readings were multiplied by a factor of 5
Markets Aspergillus spp Penicillium spp Fusarium spp Others spp Giaki 4444a 22222a 955556d 0.0a Kanyakine 0.0a 6667a 102222ab 2222a Mariene 8889a 11111a 440000abc 13333b Chaaria 64444b 6667a 300000abc 0.0a Mikumbune- 8889a 42222a 188889abc 0.0a Nkubu Gakoromone 40000ab 57778ab 117778ab 0.0a Ntaharene 0.0a 0.0a 666222cd 0.0a Mitunguu 20000a 106667bc 13333a 0.0a Ndurumo 17778a 4444a 600000bcd 6667ab Igoji 4444a 142222c 2444a 0.0a Grand mean 16889 40000 340444 2222 C.V% 44 13.2 4.9 75.5 LSD 38000.8 51401 458994.2 10512.4 F.pr 0.022 <.001 <.001 0.195
FUNGAL SPECIES PREVALENCE MARKETS F.oxysporium F.proliferatum F.verticilioides A.flavus A.parasiticus A.niger A.ochraceous Giaki 0a 0.0a 47778d 0.0a 0.0a 0.0a 0.00a Kanyakine 0a 0.0a 5111ab 0.0a 0.0a 0.0a 0.00a Mitunguu 0a 0.0a 111a 0.0a 0.0a 111.1a 0.00a Ndurumo 0a 0.0a 30000bcd 888.9b 333.3a 0.00a Ntaharene 0a 0.0a 3311cd 0.0a 0.0a 0.0a 0.00a Igoji 111a 0.0a 1111a 222.2ab 0.0a 0.0a 0.00a Gakoromone 444a 1222.2b 4222ab 888.9b 1222.2b 0.0a 0.00a Mikumbune- Nkubu 667a 111.1a 8889abc 444.4ab 0.0a 0.0a 0.00a Mariene 1111a 0.0a 20889abc 444.4ab 0.0a 0.0a 0.00a Chaaria 9222a 333.3ab 18444abc 0.0a 0.0a 0.0a 111.11a Grand mean 1156 167 16967 289 156 11 11 CV 150.9 156.2 12.2 48.0 44.6 173.2 173.2 LSD 8220.9 928.7 24186.5 709.8 648.7 98.9 98.9 Fpr 0.480 0.217 0.001 0.041 0.006 0.447 0.447
F.proliferatum F.verticillioides F.oxysporium
A.niger A.favus A.parasiticus A.ochraceous
MYCOTOXINS Markets Aflatoxins Fumonisins Giaki 0.00a 6202c Kanyakine 0.00a 1191ab Mariene 0.00a 1358ab Chaaria 0.31a 2134ab Mikumbune- 0.74a 1541ab Nkubu Gakoromone 0.94a 299a Ntaharene 1.47a 2156ab Mitunguu 3.92a 1359ab Ndurumo 44.67a 3485b Igoji 690.37b 107a Grand mean 74 1983 C.V% 0.0 0.0 LSD 311.2 2155.1 F.pr <.001 <.001
DISCUSSION Chaaria was significant different in Aspergillus spp prevalence while all the other locations were not significantly different. Giaki and Ndurumo were significant similar but were more prevalent with toxigenic Fusarium spp. F. verticillioides were more prevalent which translated into high levels of fumonisins contamination. Results of aflatoxins showed that only Igoji had a mean greater than the grand mean and was significant different from the other locations. It was higher than the standard level of 20ppb. Results of fumonisins showed that only Gakoromone and Igoji had a mean less than grand mean and was not significant different. Giaki and Ndurumo were significantly and exceeded the standard level of 1000ppb.
CONCLUSION AND RECOMMENDATION The results showed that Aspergillus spp was more prevalent in Chaaria, Gakoromone, Mitunguu and Ndurumo Giaki, Mariene, Ntaharene and Ndurumo showed more prevalence of Fusarium spp Igoji showed high levels of aflatoxins beyond the standard level. Giaki, Chaaria, Ntaharene and Ndurumo showed high levels of fumonisins that was beyond the grand mean. Results showed wide spread of infestation and contamination of maize by Fusarium spp and fumonisins toxins, Aspergillus spp and aflatoxins which translates to high exposure in the high risks population necessitating urgent interventions measures to curb the long-term health consequences in the population Therefore serve the purpose of alerting the farmers and the consumers on the dangers of consuming contaminated