Microbial Analysis Of Raw Milk Around Small Scale Farmers In Harrismith Freestate, South Africa

Abstract

Food manufacturing and agricultural industry have an ancient history of been observed to provide the most favourable conditions for the multiplication and distribution of microorganisms. These microorganisms may be found in the air (airborne), food (milk) and at the surrounding environment. Food handlers have also been found to harbour some of these microorganisms on their hands or skin surfaces. Dairy environment have been receiving quite an extensive attention especially on the composition of microbes in milk. However, studies that have been conducted mostly utilized conventional/traditional microbiological techniques. Hence, there is still lack of research in South Africa that is focusing on molecular techniques to quantify these microorganisms in raw milk. The overall aim of this dissertation was to assess different microorganisms confined in raw milk from small-scale farmers in the Eastern part of the Free State Province, South Africa. With reference to the main aim of this study, the objectives of the present study were to use molecular techniques to quantify five mostly isolated microorganisms causing subclinical mastitis in bovine .i.e. E. coli, S. aureus, S. agalactiae, S. dysgalactiae and S. uberis. Then lastly, a metagenomic analysis of raw milk was conducted by targeting the 16S rRNA gene using high throughput sequencing. The findings of this study in relation to microbial composition as per Chapter 2 showed a high microbial contamination of raw milk and has clearly indicated the need for training of all employees and the enforcement of health and hygiene measures within the dairy environment. While investigating the prevalence of subclinical mastitis around these farms, the author came across some interesting findings. The author isolated streptococcal species that are more prevalent/isolated in the hospital environment especially on samples derived from human subjects after/during streptococcal infections such as meningitis. Instead of isolating streptococcal species more prevalent on the dairy environment such as, S. dysgalactiae or S. uberis, the author identified S. mutans, S. Salivarius, S. pneumonia and S. sanguis which may entail that the employees around the farms are/were the carriers of these species. The isolation of microorganisms associated with food spoilage and foodborne disease outbreaks, which are known as indicator organisms such as Escherichia coli, Staphylococcus and Bacillus from both air and surface samples, signified possible faecal contamination and could be attributed to poor health and hygiene practices at the dairy farm plant. Despite the isolation of microorganisms associated with food spoilage and foodborne disease outbreaks, the isolation of microorganisms not usually associated with the food processing industry (usually associated with hospital environments) was an enormous and serious concern which suggested a need for further investigations at dairy farm plants as the implications of these pathogenic microorganisms in food is not known.