Incidence and pathogenicity profile of Listeria sp. isolated from food and environmental samples in Nsukka, Nigeria

Samples of beef, pork, goat meat, poultry, fish and vegetables purchased from a local market located in Nsukka, Enugu State, Nigeria were examined for the presence of Listeria species. Surface swab samples taken from butchers’ tables as well as soil samples from the field where cows and pigs were kept before slaughter were examined. Listeria species were isolated from all samples except the pork and goat meat samples. The highest incidence (100%) was observed in the soil and surface swabsamples, respectively, followed by the vegetable samples (85%) and the beef samples (80%). Only Listeria monocytogenes and Listeria ivanovii were pathogenic to test animals causing death within five days. L. monocytogenes induced pathological changes characterized by abscesses in the liver, pericarditis and frank haemorrhage in the kidneys. The most notable change was the accumulation of mononuclear cells in the loose connective tissue surrounding the bile ducts. This study shows thatthere is a high incidence of listerial organisms in various key elements of the Nigerian environment, including soil and foods of both animal and plant origin, which may pose a health risk for high-risk individuals. The study goes further to establish the major target organs of attack of the pathogenic Listeria species

Culture conditions for endo-β-glucanase production by paecilomyces species

Production of endoglucanase (E.C.3.2.1.4) by Paecilomyces sp on different cellulose substrates, nitrogen sources, surfactants, pH, temperature and aeration was studied. Optimal enzyme production was obtained in a salt medium containing ammonium sulphate (0.5%w/v) and rice hull (0.5%w/v) at an initial pH of 5.0 at 30°C under the shake flask condition. Addition of reduced enzymes production. Time course for endoglucanase production by the organism showed that enzyme production followed the same pattern as the extracellular protein synthesis and increased with the exponential growth phase. The highest enzyme production (6.4UmL-1) was obtained on the eighth day of incubation at the culture pH of 4.5.Bio-Research Vol. 3(1) 2005: 26-3

Preliminary studies on the endo-xylanase and acetyl esterase of Clostridium thermohydrosulfuricum (JW 102)

Clostridium thermohydrosulfuricum (JW102) produced low levels of xylanase in mineral medium containing yeast extract and beechwood xylan. Production of xylanase was highest at growth temperatures of 62 – 64oC. Both xylan and xylose supported acetyl esterase production. Xylose, as sole carbon source, supported the production of slightly more acetyl esterase than xylan, while enzyme produced in the presence of xylan was relatively more stable in the fermentation medium, maintaining over 80% of peak activity after 20 hours. Acetyl esterase activity was highest at assay pH of 6.5. At pH 5.5 and 6.0, enzyme activity was, respectively, 5% and 22% of that recorded at pH 6.5. Key Words: Hemicellulases, Clostridium thermohydrosulfuricum, xylanase, acetyl esterase, beeechwood xylan. Bio-Research Vol.1(2) 2003: 1-