This study scientifically examined the phytochemistry, antioxidant and antimicrobial potencies of two organic extracts of Pleurotus ostreatus. Generally, both extracts were effective against 89.8% of the isolates tested with Bacillus subtilis (7.6 -7.8 mm), Escherichia coli (7.6 -8.2 mm) and Saccharomycee cerevisae (10.5 -10.8 mm) exhibiting highest gram ±ve, gram -ve and fungal susceptibilities by agar well diffusion method, respectively. However, petroleum ether extract (PE) exhibited greater anti-gram negative bacterial activity than the acetone extract (AE) and further produced growth inhibition of these isolates in broth. Compared to PE, the acetone extract elicited higher total phenolic content and in vitro antioxidant capacity. Phytochemical analyses of the extracts revealed low to moderate levels of terpenoids, tannins, steroidal glycosides and carbohydrates, while flavonoids, alkaloids and cynogenic glycosides were not detected. The results indicate that P. ostreatus possesses antimicrobial and antioxidant potentials.

Lactobacillus plantarum belongs to the Lactobacillus caseiPediococcus phylogenetic group of the genus Lactobacillus (Hammes & Vogel, 1995) and in particular to the L. plantarum phylogenetic subgroup (Hammes & Hertel, 2003). This species is characterized by many metabolic activities that allow it to colonize different environments such as dairy products, pickled vegetables, fish products, silage, wine as well as mammal intestinal tracts (Vescovo et al., 1993). The species is highly heterogeneous (Dellaglio et al., 1975). Several studies, which have tried to elucidate intraspecific relationships, led to the description of two novel species: Lactobacillus pentosus and Lactobacillus paraplantarum (Zanoni et al., 1987;Curk et al., 1996). These three closely related species cannot be distinguished by 16S rRNA gene sequence analysis because they show 99 % sequence similarity. They also have very similar fermentation abilities: L. pentosus can be differentiated from L. plantarum only by its capacity to ferment glycerol and xylose (Zanoni et al., 1987). Some exceptions, however, exist: some L. plantarum strains are able to metabolize glycerol as with L. pentosus and not all L. pentosus strains can metabolize xylose . Fermentation differences between L. plantarum and L. paraplantarum are even less helpful: the main difference is that strains of the latter species metabolize methyl a-D-glucopyranoside, whereas 66 % of L. plantarum strains cannot .With regard to molecular techniques, L. plantarum, L. pentosus and L. paraplantarum can be rapidly distinguished using PCR amplification targeting the 16S/23S rRNA gene spacer region (Berthier & Ehrlich, 1998) or the recA gene as described by Torriani et al. (2001). Moreover, a polyphasic approach with a combination of RAPD (randomly amplified polymorphic DNA)-PCR, Southern hybridization and phenotypic traits not only distinguished the three species L. plantarum, L. paraplantarum and L. pentosus, but also revealed the presence of two groups of strains in the species L. plantarum (Bringel et al., 2001): 90 % of these were closely linked to the L. plantarum type strain, ATCC 14917 T , and 10 % (14 strains) formed a distinct group. We report here the analyses performed on those 14 'atypical' strains and, on the basis of collected data, a novel subspecies of L. plantarum is proposed.

No abstract

As part of a programme to formulate foods to aid the control of diarrhoeal diseases, an improved ogi (the commonest weaning food in Nigeria) named DogiK has been developed. DogiK was produced by using Lactobacillus starter cultures with antimicrobial activity against diarrhoeagenic bacteria and also possessing amylolytic activity. The survival of diarrhoeagenic bacteria was investigated in locally-fermented ogi and in DogiK. The foods were inoculated with cell suspensions of Salmonella, Shigella, Campylobacter, Aeromonas, Pleisiomonas, Enteropathogenic and Enterotoxigenic Escherichia coli, Yersinia enterocolitica, and Vibrio cholerae. None of the diarrhoeagenic bacteria were detected in DogiK after 6 h whereas in the local ogi Salmonella, E. coli, and Shigella survived for 24 h or more, but showed a sharp decrease in numbers, while V. cholerae survived for 12 h. DogiK is active whether cooked or uncooked and exhibited inhibition of pathogens at neutral pH. It gives consistent quality. Preliminary investigation indicates possession of a better shelf life. Thus, DogiK may have a potential use in the prevention and treatment of diarrhoea.

SUMMARYIn an epidemiological survey, plasmid profiles and antimicrobial susceptibility testing of 100 shigella isolates in Lagos, Nigeria was done. All the isolates were sensitive to nalidixic acid, nitrofurantoin and ciprofloxacin. The commonest antimicrobial susceptibility pattern was resistance to ampicillin, colistin sulphate, co-trimoxazole, streptomycin and tetracycline. All but 4 of 100 isolates screened contained one or more plasmids. Plasmid profile analysis distinguished more strains than did antimicrobial susceptibility patterns. A total of 36 isolates was able to transfer resistance plasmids toEscherichia coliK-12 by conjugation. Usingin vitrotransformation, seven isolates transferred resistance. These plasmids specified resistance to tetracycline, streptomycin, sulphonamide, trimethoprim and ampicillin.

Two hundred isolates of Lactobacillus were obtained from seven indigenous fermented foods namely: 'fufu' (fermented cassava), 'iru' (fermented African locust bean), 'kenkey' and 'ogi' (fermented maize), 'kunu-zarki' (fermented millet), 'ugba' (fermented African oil bean) and 'wara' (fermented skimmed cow milk). Lactobacillus species identified were Lacto­ bacillus casei (17.0%), L. lactis (4.5%), L. plantarum (41.5%), L. brevis (11.5%), L. jensenii (5.5%), L. acidophilus (3.5%) L. cellobiosus (5.0%), L. delbrueckii (2.5%), L. salivarius (3.5%), L. leichmannii (3.5%) and L. fermentum (2.0%). The commonest species isolated was L. plantarum. This paper highlight the importance of Lactobacillus in the processing of African fermented foods.

No abstract

A total of 635 clinically diagnosed typhoid fever patients were bled from three different health institutions in the metropolis of Lagos, Nigeria over a period of 15 months, May 1997 to July 1998. Out of the total blood cultured, 101 (15.9% ) isolates of Salmonella species were isolated of which 68 (67.3% ) were S. typhi, 17 (16.8% ) and 16 (15.8% ) were S. paratyphi A and S. arizonae respectively. The overall isolation rate of S. typhi among patients is 10.7% , with most isolates 45.9% found among the severely-ill young adults, age group 1 6 -30 years. All isolates were subjected to anti-microbial susceptibility testing using 12 different antibiotics: chloramphenicol, ampicillin, cotrimoxazole, gentamicin, colistin sulfate, nalidixic acid, nitrofurantoin, cefotaxime, tetracycline, streptomycin, ofloxacin and ciprofloxacin. All the S. typhi and S. paratyphi A isolates showed resistance to two or more of the 10 of 12 antibiotics tested particularly the 3-first-line antibiotics commonly used (chloramphenicol, ampicillin and cotrim oxazole) in the treatment of typhoid fever in Nigeria. No isolate showed resistance to ofloxacin and ciprofloxacin, however, nalidixic acid and gentamicin showed a moderate and appreciable inhibition to most of our isolates.