Characterisation, optimisation and evaluation of endogenous Biosurfactants from broiler Git Microbes For The Broiler Feed Industry

Abstract

Antimicrobial drug resistance from improper use of antibiotics in livestock production, especially broiler meat, is a growing hazard for humans worldwide, with the current death rate in excess of 700 000 people per annum linked to the problem. Microorganisms are a rich source of structurally distinct bioactive compounds designed to protect the microbes. The compounds can be of use in the feed industry to protect the animals or birds against pathogenic microbes. A study was carried out to determine biosurfactant secreting microbes followed by characterising the chemical properties of biosurfactants and optimising their cultivation medium. Lastly the study evaluated the biosurfactants’ in-vivo impacts on performance using Cobb500 broiler chickens. Gastrointestinal tract (GIT) organs were divided into crop, gizzard, small and large intestine and the digesta samples were removed aseptically for culturing. Biosurfactant screening assays: haemolytic activity, oil spread technique, and oil drop collapse were employed to find bacteria that released biosurfactants. The isolated bacteria positive for biosurfactant production were then identified using 16S rRNA method. Bacteria producing biosurfactants were then cultured using batch fermentation to optimise the production of the compounds. Microbial biosurfactants, extracted using centrifugation technique and polar solvents, were characterised chemically (Gas Chromatography and Mass Spectrometry, Fourier Transform Infra-Red and radio receptor assay technique) and using in-vivo experiments to ascertain their effects on carcass quality and immune properties. Genstat 18th edition was used for analysis of variance and separation of means using Fischer’s least significant difference (LSD). Microbial populations in different areas of the bird’s GIT varied significantly (p<0.001) with a higher population in the proximal gut (crop and gizzard). The radio receptor assay technique demonstrated that the recovered crude biosurfactants contain tetracyclines and sulfa-like compounds, which were linked to the observed antibacterial activity against E. coli and S. aureus. The clearance zones on haemolytic activity for biosurfactants isolated from the small and large intestines were not significantly different (P>0.05). Biosurfactants derived from the small intestine showed a greater clearance zone on oil spread test (8.4 mm) and on sheep blood agar (5.6 mm), and an antibacterial inhibition zone of 22 mm at a 5 percent m/v inclusion level. The biosurfactant secreting bacterium was identified as a non-pathogenic Escherichia coli bacterium similar to E. coli strain (7.1994/NIST 0056) with a genomic matching index of 98.29 percent using the 16S RNA method. The secreted biosurfactant substance was identified as a decane derivative without hydrate and containing a compound with double and triple vii bonds that is related to ketones. The FTIR showed seven peaks in the biosurfactants, indicating that the examined biosurfactant is a small organic compound. There were no significant differences (p>0.05) in weight gain, drip loss, weight of internal organs (heart, spleen, gizzard, liver), and small intestine length between the biosurfactant supplemented group and the control experiments. Immunoassays revealed a negative C-reactive protein (CRP) test for the biosurfactant supplemented group and a positive for the negative and positive control treatment groups. The biosurfactant-supplemented treatment group had lower globulin concentrations (g/L), and WBC (103 microlitre) than the control treatments. This demonstrates biosurfactants’ ability to sanitise the gastrointestinal system of birds against potential contaminants. The study concluded that endogenous biosurfactants secreted by the E coli strain (7.1994/NIST 0056) is a glycolipid which can be employed as a non-nutritive feed additive with benefits to broiler immunity. The researcher recommends further research and development on optimisation of current biosurfactant extraction processes to make it more cost effective. Furthermore, a fermentation system that cuts the process of extracting biosurfactants, enabling extraction of biosurfactants without the need for centrifugation employing less solvents. The biosurfactant product can be commercialised.