Microbial flora associated with the soils of edible snail farms in Southern Nigeria

Abstract

Microbial analysis of soil samples collected from snail farms in two different locations (Ughelli, Delta State and Obokofia, Imo State) in southern Nigeria were carried out and compared with that of soil samples collected from ordinary farmlands in these locations.The snail species encountered in this study were Achatina achatina and Archachatina marginata, which are the popular species of economic interest in Nigeria. Analysis of snail farm soil indicated a high number of heterotrophic bacteria (7.20x10⁵ to 9.60x10⁵ cfu/g) than the farmland soil (1.06x10⁵ to 4.40x10⁵ cfu/g). The snail shell effluent contained 1.9x10⁵ to 2.28x10⁵ cfu/ml. Coliform bacteria was 1200 MPN/100g in the snail farm soil, 260 MPN/100g in the unimpacted farmland soil, 480 MPN/100ml in the visceral mass and 160MPN/100ml in the sail shell effluent. Counts of Vibrios recorded were in the ranges of 1.80x10⁴ to 3.2x10⁴ cfu/g for the snail farm soil, 4.0x10⁴ to 2.70x10⁵cfu/ml in the snail shell affluent and 0 to 1.30x10⁴ cfu/ml in the visceral mass. None was recorded in the unimpacted farmland soil. Staphylococcus species was in the range of 1.48x10³ to 2.6x10³ to 1.6x10 ⁴ cfu/ml in the snail shell effluent and 2.40x10 to 4.8x10cfu/ml in the visceral mass. Pseudomonas/Aeromonas species were low in number in the farmland soil (0 to 1.06x10² cfu/g), snail farm soil (1.1x10³ to 2.1x10³cfu/g), snail shell effluent (7.1x10² to 2.20x10³ cfu/ml) and visceral mass (2.69x10² to 3.2x10² cfu/ml).Other bacterial genera isolated from the farms included Salmonella, Escherichia coli, Bacillus, Klebsiella, Streptococcus and Proteus, and these occurred in higher numbers than in the unimpacted farmland soil.

Nigerian Journal of Soil Science Vol. 15 2005: 75-80