Toxin production in food as influenced by pH, thermal treatment and chemical preservatives

Sixteen foods borne bacteria were isolated from raw food samples including okro, carrot, spinach, pepper, tomato, onion and cooked food samples (rice, yam, beans, meat and plantain). The isolateswere characterized and identified as Bacillus brevis, Bacillus congulans, Bacillus polymyxa, Bacillus lentus, Bacillus megaterium, Bacillus subtilis, Acinetobacter spp., Citrobacter freundii, Klebsiella aerogenes, Streptococcus agalactiae, Alcaligenes spp., Corynebacterium spp., Enterobacter aerogenes, Enterobacter spp. and Staphylococcus epidermidis. These isolates were screened on egg yolk agar fortoxigenic properties and thirteen of the sixteen were positive for toxin production while three were negative. Six out of the thirteen toxigenic bacterial were selected for further work. These were; E. coli,K. aerogenes, C. freundii, B. polymyxa, S. epidermidis and E. aerogenes. The effect of pH, thermal treatment and chemical preservatives on the growth rate and toxin elaboration of E. coli, K. aerogenes, C. freundii, B. polymyxa, S. epidermidis and E. aerogenes was studied. It was observed that E. coli had no viable growth until 48 h of incubation, while the other five isolates had visible growth right from the 24 h of incubation. Also E. coli did not produce toxin until the 96th hour of incubation; K. aerogenes and E. aerogenes were able to produce toxin at 24 h of incubation, while C. freundii, B. polymyxa and S.epidermidis produced toxin at 48 h of incubation. Also, 44°C was not suitable for toxin production. pH 3 and 5 were less favorable for toxin production despite the fact that isolates were able to grow at different temperature and pH ranges. The isolate were more sensitive to sodium metabisulfite than benzoic acid. Also, E. coli and K. aerogenes were able to elaborate toxin in their dormant state with 750mg of sodium metabisulfite

Determination of the growth rate and volume of lipid produced by Lipomyces species isolated from shear butter leaf (Vitellaria paradoxa)

A Lipomyces strains was isolated from shear butter leaf (Vitellaria paradoxa) by placing the leaf sample in 10 ml of sterile distilled water containing 0.002 g of potassium dihydrogen phosphate and incubatedfor 3 days at 28oC. A drop of this was subsequently streaked nitrogen free medium. For determination of growth rate and volume of lipid produced, 24 h culture of the Lipomyces species isolated was washed into each of the following medium: yeast extract both (YE), nitrogen free broth (NF), maize broth free of salts (MF), maize broth with salts (MB), sorghum broth with salts (SB) and sorghum broth free of salts (SF). These were incubated for 7 days at 28oC on a shaker, and the lipid produced was extracted by using diethyl ether. The Lipomyces species was found to be able to grow and produce lipid more efficiently in yeast extract broth than in other medium used. The organism produced 25 ml of lipid per 8 g of glucose in yeast extract broth

Biological studies on albino rats fed with Sorghum bicolorstarch hydrolyzed with &#8733-amylase from Rhizopus sp.

Partially purified amylase was extracted from the culture medium of Rhizopus sp. grown in potato dextrose broth for 48 h at room temperature by precipitation with 96.9% ethanol. The enzyme was usedto hydrolyze sorghum starch. The hydrolyzed product was afterwards formulated into rat feed, which was fed to albino rats for a period of thirty days. The average daily body weight of the albino rats fed with hydrolyzed formulated feed on the 30th day of the experiment was 131 g while the values recorded for the groups fed with unhydrolyzed and commercial feed were 120 and 97.4 grams respectively. Thehematological analysis revealed that the packed cell volume (PCV), Hemoglobin (Hb), red blood cells (RBC), mean cell hemoglobin concentration (MCHC) of the group fed with hydrolyzed formulated feed of 51.8%, 16.9 g/dl, 8.7 x 105 ƒÊl-1 and 32.7%, respectively, were higher than the experimental animals fed with commercial feed with values of 44.2%, 14.4 g/dl, 7.7 x 10