SOURCE:

Faculty: Arts
Department: Applied Microbiology And Brewing

CONTRIBUTORS:

Ikele, O.M;
Ezeonu, I.M;

ABSTRACT:

Probiotics are microorganisms which when consumed, confer certain health benefits to man while prebiotics are non-digestible food substances, mainly of carbohydrate complexes, which when consumed, provide a beneficial physiological effect on the host by selectively stimulating the growth of beneficial indigenous bacteria. This work studied the probiotic and prebiotic effects of Lactobacillus sp and Ocimum gratissimum respectively, in the control of chicken colibacillosis. Lactobacillus spp and E. coli were isolated from Nono and identified by standard microbiological methods. One isolate each of Lactobacillus and E. coli was selected out of five and twenty isolates respectively, for use in subsequent experiments based on observed Lactobacillus probiotic and E. coli avian pathogenic activities. The selected isolates were subjected to molecular typing for accurate identification. The phytochemical composition of O. gratissimum was determined by standard methods and its prebiotic components identified using thin layer chromatography. Both probiotic Lactobacillus and O. gratissimum were evaluated for antibacterial activity against the avian pathogenic E. coli (APEC) using agar well diffusion assays, while the minimum inhibitory concentration (MIC) of O. gratissimum was determined by tube dilution. In vivo studies were conducted using chicks (Gallus domesticus) that were screened and found to be free of colibacillosis. Three-weekold broiler chicks were divided into six groups of ten chicks each viz: A (healthy control), B (infected and untreated), C (antibiotic control), D (infected and treated with Lactobacillus), E (Lactobacillus prohylaxis) and F (infected and treated with O. gratissimum). The birds were orally infected with 1.5 ml of 1.3 x107 cfu/ml of APEC. Groups C, D and F infections were controlled using 15g/L Norfloxacin, 1.5 ml of 1.1 x109 cfu/ml Lactobacillus and 40 g/L O. gratissimum extract administered orally respectively. Group E had oral infusion of 1.5 ml of 1.1x109 cfu/ml Lactobacillus before infection. The immune-modulatory, protective and growth-enhancing efficacies of Lactobacillusand O. gratissimum administrationwere evaluated using measurements of growth and haematological parameters as well as histological examination of tissues. Blood samples used for evaluation were collected through venipuncture, fecal samples were aseptically collected from the intestines and caeca for microbial evaluation, while histological evaluation was done using the intestinal and caecal tissues. Molecular typing of the selected Lactobacillus and E. coli species identified them as L. casei and E. coli O157:H7 strain sakaii respectively. Phytoconstituents identified from ethanolic extract of O. gratissimum included alkaloids, saponins, flavonoids, tannins, terpenoids and ascorbic acid. A prebiotic fructooligosaccharide (FOS) was also identified from the extract. Both natural therapies had antibacterial activity against APEC in vitro. O. gratissimum had an MIC of 31.25 mg/ml against APEC with a 13 mm zone of inhibition, while L. casei cell free supernatant inhibited APEC with 10 mm zone of inhibition in vitro. In vivo evaluation showed that there was appreciable weight gain and specific growth rate in the chicks except for group B. Administration of the probiotic and prebiotic significantly increased (p<0.05) blood levels of sodium, chlorine and bicarbonate, while there was no significant difference in potassium (p>0.05).The haemoglobin, white blood cell, lymphocyte and neutrophil levels significantly increased (p<0.05), while no significant difference (p>0.05) existed in their monocyte, eosinophil and basophil levels. There was no significant difference (p>0.05) observed in the liver enzymes with the administration of probiotics and prebiotics; same was observed in urea, creatinine and C-reactive protein levels. Microbial assessment revealed a decrease in the total coliform count and total E. coli count of the intestine and caecum microbiota for groups C, D, E and F. There was also an observed increase in the total lactic acid bacteria count of groups D and E intestinal microbiota; as well as in groups D, E and F caecum microbiota. Histology of the intestinal and caecal tissues showed a level of tissue repair in groups C, D, E and F; while group B showed gross damage of tissues. Findings from this study revealed that L. casei and O. gratissimum could be used as antibiotic alternatives in the control of chicken colibacillosis, growth enhancement of broilers and their overall gut health maintenance. Furthermore, the presence of APEC in Nono signifies feacal contamination of the product and points at the need to improve on aseptic production of the milk product.