Phenotypic characterisation and assessment of the inhibitory potential of Lactobacillus isolates from different sources

Six strains of Lactobacillus spp. were isolated from fermenting corn slurry, fresh cow milk, and the faeces of pig, albino rat, and human infant. Their inhibitory action was tested against some spoilage and pathogenic bacteria. Lactobacillus acidophilus isolated from milk was found to display a higher antagonistic effect with zones of inhibition of 6 and 15 mm against E. coli and Pseudomonas aeruginosa respectively. This isolate was incapable of inhibiting the other indicator bacteria. The other isolates have zones of inhibition ranging between 1 to 4 mm. Characterisation of the microbial metabolic product for antimicrobial agents reveals that lactic acid may be responsible for the inhibition of the indicator organisms. Keywords: Lactobacilli, biopreservatives, pathogenic bacteria. African Journal of Biotechnology Vol.3(7) 2004: 355-35

Performance of rats orogastrically dosed with faecal strains of Lactobacillus acidophilus and challenged with Escherichia coli

Albino rats (Rattus norvegicus) were orogastrically dosed with faecal strains of Lactobacillus acidophilus and simultaneously infected with Escherichia coli, while the control was challenged with E. coli alone. The treatment was repeated the second day and post ingestion period of 18 days follow. It was observed that rats dosed with L. acidophilus and simultaneously challenged with E. coli treatments have better performances when compared with the control for daily weight gain, total weight gain and feed conversion rate. Faecal materials of rats dosed and challenged do not show sign of diarrhoea which was observed in the E. coli only treated rats. Key Words: Rats, orogastric, Lactobacillus acidophilus. African Journal of Biotechnology Vol.3(8) 2004: 409-41

Effect of garlic (Allium sativum) on Salmonella typhi infection, gastrointestinal flora and hematological parameters of albino rats

The effect of consumption of garlic (Allium sativum) in treating Salmonella typhi infection and on the gastrointestinal flora and hematological parameters of rats was investigated. Crude garlic extract inhibited the growth of S. typhi on agar plate with a zone of inhibition averaging 23.8 mm in diameter using the agar diffusion assay. This inhibition was superior to that of all the conventional antibiotics used except streptomycin which gave a growth inhibitory value of 24.0 mm. In the in vivo assay, although, pretreatment with the extract did not protect rats orogastrically dosed with the infective dose of S. typhi from the infection, the consumption of crude garlic extract however, caused a significant (p<0.05) reduction in the number of S. typhi in the feaces of the infected rats from 2.0 x 108 to 9.0 x 101 cfu/ml and also reduced the duration of infection from 5 to 3 days. On the effect of consumption of garlic extract on the type and load of gastrointestinal flora and hematological parameters of rats, garlic extract caused a significant (p<0.05) reduction in the type of bacteria present in the gastrointestinal tract of rats fed 1 ml daily for 7 weeks from six microbial types to one microbial species, reduction in microbial load of the flora from 1.64 x 1012 to 1.3 x 107 cfu/ml, reduction in packed cell volume (PCV), total white blood cells (WBC) and lymphocytes counts but caused an increase in neutrophils and monocytes counts of the rats. The observed increases in the neutrophils and monocytes counts of the blood suggested that garlic may possess immune-stimulatory effect in addition to its antibacterial effect.Key words: Salmonella typhi, Allium sativum, antibacterial activity, rats

Microbial Quality and Sensory Properties of Ogiri Produced from Watermelon (Citrullus lanatus) Seed

The aim is to study the microorganisms involved in fermentation, their occurrence and the organoleptic properties of fermented watermelon (Citrullus lanatus) seeds. The watermelon seeds were dehulled, sorted, washed and boiled for 4 hours and fermented naturally for nine days. Microorganisms isolated from the fermenting watermelon seeds were Bacillus sp, Lactococcus sp, Pediococcus sp, Streptococcus sp, Micrococcus sp and Alcaligenes ps for bacterial, while the fungi obtained were Mucor sp, Rhizopus sp, Fusarium sp, Candida sp and Saccharomyces sp. The bacterial count increased from 4 x101 cfu/mL to 1.21 x 1010 cfu/mL while fungal count also increased from 8 x 101sfu/mL to 1.2 x 109sfu/mL during the period of fermentation. The pH and temperature increased from 6.3 to 8.7 and 29oC to 40oC respectively. The total titratable acidity decreased from 0.176% to 0.027%. The mean sensory characteristics value of fermented sample as scored by the panelist shows that the texture of the fermenting sample become softer as fermentation progressed. The aroma became more pungent with a strong ammonia odour responsible for the characteristic flavour and a darker colour of product. The overall acceptability of fermented sample was adjudged like very much while the sample bought from the market was adjudged like moderately

Safety and protective effect of Lactobacillus acidophilus and Lactobacillus casei used as probiotic agent in vivo

The protective effect of Lactobacillus acidophilus and Lactobacillus casei, isolated from fresh cow milk, was studied in vivo. Toxicological data of rat serum revealed that the Lactobacillus isolates had liver improvement functions. Serum alanine aminotransferase (ALT) activities of the rats dosed with Lactobacillus isolates alone were lower (15.50 and 18.27 iu/l) than the control. There was a reduction in the count of enterobacteria in rats dosed with L. casei after 3 days of feeding trials. Protection of the gastrointestinal tract (GIT) by these isolates was also observed. Histopathological data confirmed partial protection of the GIT in rats dosed with Lactobacillus isolates and simultaneously infected with Escherichia coli. L. casei was generally observed to have a better effect than L. acidophilus in terms of liver function improvement, anticholesterolaemic effect, and reduction of enterobacteria in the GIT. Key words: Probiotic, protection, Lactobacillus African Journal of Biotechnology Vol.2(11) 2003: 448-45

EFFECT OF SUBMERGED FERMENTATION ON THE ANTIBACTERIAL AND ANTIOXIDANT PROPERTIES OF AQUEOUS EXTRACTS OBTAINED FROM VOACANGA AFRICANA STAPF SEED

Voacanga africana Stapf which belongs to the family, Apocynaceae is among useful medicinal plants of West Africa. The present study investigates the antibacterial and antioxidant properties of aqueous extracts obtained from raw and fermented V. africana. One portion of V. africana was subjected to submerged fermentation for 7 days. Aqueous extracts of the raw and fermented samples of V. africana were obtained using standard methods. Antibacterial effect of the aqueous exracts was assessed by agar well diffusion while a battery of antioxidant test which include DPPH scavenging, ABTS, and Fe2+ chelation was employed. The bioactive compounds present in the extract were assessed using gas chromatography-mass spectrophotometer. Extract obtained from the fermented seed of V. africana had good antimicrobial effect with zones of inhibition ranging from 4.67 to 22.00 mm. Aqueous extract obtained from fermented V. africana exhibited better antioxidant capacity with DPPH scavenging effect being the highest (27.93) when compared with extract obtained from raw V. africana. Bioactive compounds such as Eicosane, 1,14-Dibromotetradecane, 7-Oxodehydroabietic acid, oleic acid and so on were present in the aqueous extract obtained from fermented V. africana. Data gathered from this study revealed that fermentation enhances the antimicrobial and anoxidant properties of V. africana. The presence of bioactive compounds in the aqueous extract of V. africana indicates that it could be a good source of natural antimicrobial and antioxidant compounds for the improvement of human health