Microbial Diversity of the Edible Dung Beetle (Aphodius rufipes) in Relation to Conventional Post-harvest Processing Practices in Minna, Nigeria

Abstract

Dung beetle larva is a traditional delicacy of the Gbagyi people of Niger State, Nigeria. The microbial load of dung beetle larva was assayed using the pour plate method while enumeration of organisms was done using the colony counter. The highest aerobic bacterial load was obtained from the external surface of fried dung beetle larvae obtained from the market, FDBM (6.53×106 cfu/mL) while the least was from fried dung beetle larva processed in the laboratory, FDBL (0.25×106 cfu/mL). Similar bacterial count was obtained from external surface of fresh dung beetle, FDB (3.0×106 cfu/mL) and sundried dung beetle, SDB (3.0×106 cfu/mL). Higher aerobic bacterial load was recorded on the whole body of FDBM (2.03×106 cfu/g) while FDB (4.9×106 cfu/g), SDB (5.1×106 cfu/g) and FDBL (5.6×106cfu/g) had similar bacterial load on their whole body. The highest anaerobic bacteria count was obtained from the external surface of FDB (9.3×106 cfu/mL) and SDB (8.7×106 cfu/mL) followed by FDBL (2.9×106 cfu/mL). The least anaerobic count was recorded on external surface of FDBM (2.5×106 cfu/mL). The highest anaerobic bacteria count was obtained from whole body of FDBM (10.9×107 cfu/g) while the least was from FDB (4.2×106 cfu/g) and FDBL (4.4×106 cfu/g). The highest fungal count was obtained from external surface (9.00×104 cfu/mL) and whole body (48.00×104 cfu/g) of FDB while the least was from FDBL external surface (5.67×104 cfu/mL) and whole body (5.00×104 cfu/g). The bacterial counts in dung beetle larva except for FDBM were within the acceptable limits when compared with the recommended limits (104 – 106 cfu/g) by International Commission on Microbiological Specification for Foods (ICMSF). The total fungal count obtained from the present study was above the recommended limit (103cfu/g). Species of Bacillus, Pseudomonas and Streptococcus were isolated from external surface of FDB and SDB respectively while FDBL had species of Bacillus and Proteus sp. on its external surface. Only Bacillus sp. was isolated from the external surface of FDBM. From the whole body of FDB and SDB, Bacillus was isolated while species of Bacillus and Proteus were isolated from FDBM. Species of Pseudomonas and Micrococcus were isolated from whole body of FDBL. Bacillus sp. was the most frequently isolated bacterium while Streptococcus sp. was the least. Aspergillus niger was the most frequent fungus isolated while Aspergillus fumigates was the least. The results of the study revealed that fried dung beetle larva prepared in the laboratory had the least microbial count. Samples of dung beetle larva studied contained both pathogenic and non-pathogenic microorganisms. Thus adequate precaution should be taken during processing and handling.