Microbiological Study Of The Intestinal And Crop Contents Of Wild And Cultivated Edible Snail

1.1 Background of the Study

The terrestrial snails like Achatina fulica, Achatina achatina and Archachatina marginata are large?sized terrestrial mollusks that can grow up to 20 cm in length and 10 cm in diameter. In these snails, the brownish shell having dark stripes generally covers half of the body (Ohlweiler, et. al., 2010). Among these, the shell of A. fulica  is smaller and can grow up to 3–4 inches, while A. achatina has a larger shell size of 10–11 inches (Uyoh et. al., 2013).

The calcareous shell of the snail when burnt, ground into powder and mixed with oil and has been applied to boils by many  indigenes of Africa as a form of treatment. Snail products such as the haemolymph are also being exploited as a cure for ailments.  The invasive land snail Achatina fulica, is a species known to  carry parasites and harbours a dense and metabolically active  microbial community, the diversity and composition of which is however unknown (Cardoso et. al., 2012).  

Apart from the conventional sources of protein; which are mainly  meat and fish, snails (molluscs) are excellent sources of protein  and mineral elements for many families. Snail meat is a nutritious  food that is high in protein, low in fat and a good source of iron (USDA, 2006). Snail meat is high in protein, iron, calcium and  phosphorus, but low in sodium, fat and cholesterol, and contains  almost all the amino acids needed by man. The meat is high in  health benefiting essential fatty acids such as linoleic and linolenic acids (Su, et. al, 2004). Furthermore, African giant snails  (Archachatina marginata and Achatina achatina) are considered  as a delicacy in Nigeria and they command high demand in the  market. Archachatina marginata is the largest known snail in  Africa. Snails have high rate of productivity or fecundity (Olawoyin and Ogogo, 2006). Though they are hermaphrodites, they practice  sexual reproduction and snails are selective in their mating  partners and sometimes uninterested in mating with other snails  of the same species originating from a considerable distance  away (Omole and Kehinde, 2005). The natural habitat of snails are  mostly found in the forest, farms and gardens where they have  unlimited vegetation to feed on. The most dominant types of  vegetation in Africa are the tropical forest and the savannah  where a wide variety of the African terrestrial Gastropods inhabit.  Most land snails, especially, the African giant land snails that are  eaten and exported are usually picked from their natural habitat.  However, with the large market for the meat, many concerns have  been raised about the reduction in their natural population. With  challenges such as depletion of the stock of wild snails, over population, high cost of conventional animal protein and also for  health reasons, the demand for snails has increased such that  commercial production is necessary. This led to the introduction of  snail breeding farms with the farm purpose of supplying snails to  meet the market demands (Raut and Barker, 2002). The close  contact of wild snails with soil and their uncontrolled feeding  pattern make the snail susceptible to microbial contamination.  Snails inherently have high populations of indigenous bacteria coliforms and other poisonous substances which they ingest (ICMSF, 2005). The meat can be easily contaminated by pathogens and serve as vehicle of transferring infectious agents to consumers (Kiran, et. al., 2006). Despite the rich nutritional values of snail, the involvement of the molluscs in the transmission of infection mostly as secondary host for pathogens makes it necessary to study the microbiology of the resident snail. The fact that consumption of field collected snails may lead to bacterial infection, the provision of a systemic farming of snails will help solve both the problem of depletion of snail populations as well as provision of a relatively wholesome meat with less microbial contaminations (Samia, et. al., 2017).

1.2 Statement of the Problem

Microorganisms have various functions and potentials and they  are found everywhere (ubiquitous). The health of humans and that of the environment is highly dependent on the surroundings, particularly the food consumed. Many bacterial and fungal species inhabit the intestinal tract and crop of snails and thus, are introduced into food chain where they are capable of causing infections if not properly processed.

1.3 Justification of the Study

Snails serve as meat and are highly proteinous for human diet. Snails can be gotten from the wild which is their natural environment such as bushes, or from breeding farms where they are cultivated. These environments give them different feeding habits. The wild type snails feed freely from the plants, soil, and other components of the environment while the cultivated ones eat only special feeds from different manufacturers. This is likely to make their intestinal flora different. Examination of the intestinal tract and crop contents of these snails therefore become importance in understanding the microbial attributes as well as the health significance of the isolates since they can be introduced into food chain. 

 1.4 Aim and Objectives

The study intends to carry out microbial composition analysis of the intestinal tract and crop contents of wild and cultivated edible snails.

The objectives are as follows:

1. To determine the microbial load of the snails intestinal tract and crop contents by serial dilution and spread plate method.

2. To isolate and identify the types of microorganisms present in these two organs of the snails by morphological and physiological studies. 

3. To determine the predominant organisms in each organ.

4. To determine the potentials in the spread of antibiotics resistance by checking their susceptibility to commonly used antibiotics.