Chromatium species: an emerging bioindicator of crude oil pollution of tidal mud flats in the Niger Delta mangrove ecosystem, Nigeria.

Establishing microbiological indices for the monitoring of environmental decay by crude oil pollution in the Niger Delta region has been a major concern of our current researches. Chromatium species, a purple, Gram positive pleomorphic, motile, microaerophlic sulfur bacterium offers a good potential for use in the assessment of the short term effects of oil pollution of tidal mud flats in the Niger Delta mangrove ecosystem. Its response to the November 22, 2003 spillage at the Qua Iboe Estuary and the adjoining Cross River Estuary was investigated. Our results have revealed that the sulphur bacterium is easily identified and widely distributed in the epipellic sediment of the mangrove ecosystem but very sensitive to hydrocarbon pollution. The bacterium was readily detected in the tidal mud flats containing as much as 2.0 mg kg(-1) but not detected in sediment with THC level of 3.65 mg kg(-1) and above. It is thus, suggestive that the threshold and lethal limits of effect of hydrocarbons against the sulfur bacterium lies between 2.04 and 3.65 mg kg(-1). These imply that in any case of crude oil pollution that Chromatium is not detected during monitoring the THC levels of the sediment may have been raised to a level close to or above 3.65 mg kg(-1). Statistical analysis of the relationship between THC level and density of Chromatium in sediment revealed a significant (p < 0.05) negative relationship (r = -0.85) in Qua Iboe mangrove ecosystem as against an insignificant (p > 0.05) relationship (r = -0.41) recorded for the Cross River mangrove ecosystem which served as the control. The result indicates that oil pollution affect the homeostatic status of Chromatium in tidal mud flats despite its even distribution (R2 = 71.4%). The finding though not definitive may contribute to the hierarchical process of oil pollution assessment in the Niger Delta region of Nigeria. However, its effective utilization will require not only the development of a selective medium for enumeration and isolation of the bacterium but also the establishment of a defined dose-response relationship under controlled conditions which requires further research.

Productivity and distribution of epipellic microalgae along salinity gradients in mangrove swamp of the Qua Iboe Estuary (Nigeria).

Based on spatial variation in tidal mud salinity, direct gradient analysis procedures were adopted to relate the productivity and distribution of epipellic microalgae along salinity gradients in mangrove swamp of the Qua Iboe Estuary. Variations in mud salinities were due to distance from the coast, tidal incursions and freshwater input. The dilution effect of fresh water input from rainfall, urban runoff and associated freshwater creeks was most severe during the rainy season month of July, with much lower salinity levels recorded, in comparison to higher salinity values, recorded for same sampling locations during the drier month of December. In the dry season, all the microalgae species but Closterium (a genus of soft, green algae) and Oscillatoria (a cyanobacterium) species encountered in the tidal mud flats showed statistically significant negative correlations with salinity, while most microalgae species excluding Oscillatoria and Closterium species were positively correlated with the same factor during the wet season. Four Ecological Groups of microalgae, were established in the dry season month of December as against two Ecological Groups in the wet season month of July. However no microalgae species was found to occur on the highest values of mud salinity and there were overlapping range of occurrences and ecological optima for most species along the gradients.

Reduction of some toxicants in Icacina mannii by fermentation with Saccharomyces cerevisiae.

The effect of fermentation on the level of some toxic components (hydrocyanic acid, phytic acid and oxalic acid) of Icacina mannii paste was investigated. The results indicate that fermentation caused a decrease in the level of these toxicants ranging from 178 mg/kg to 70 mg/kg for hydrocyanic acid, 638 mg/kg to 463 mg/kg for oxalic acid and 49 mg/kg to 21 mg/kg for phytic acid. When the paste was supplemented with active cells of Saccharomyces cerevisiae there was a marked decrease in the level of the three toxicants ranging from 84 mg/kg to 16 mg/kg for hydrocyanic acid, 374 mg/kg to 88 mg/kg for oxalic acid and 24 mg/kg to 5 mg/kg for phytic acid. Supplementing the paste with yeast cells at a concentration of 7.5 g/kg before fermenting, resulted in approximately a 90% reduction in the level of the three toxic compounds after 144 hours of fermentation.

Utilization of cassava peels as substrate for crude protein formation.

Mash prepared from cassava peels was inoculated with either Sacchromyces cerevisiae or Candida tropicalis and then left to ferment for 7 days. Chemical analysis of the fermented mash showed substantial increase in crude protein content and decrease in carbohydrate content of the mash. The results also revealed slight increases in the ash, fibre and lipid content of the fermented mash. It was further observed that, when the mash was supplemented with inorganic nitrogen sources (urea, ammonium sulfate or sodium nitrate) before commencement of fermentation, the amount of crude protein formed was almost doubled. This enhanced crude protein production was highest in the mash supplemented with urea. Temperature of 30 degrees C, pH of 5.5 and moisture concentration of 130% were found to be optimum for crude protein formation by the organisms growing on the mash.

The effect of fermentation on the nutrient status and on some toxic components of Icacinia manni.

The effect of fermentation on the nutrient status and on some toxic components of Icacinia manni was investigated. Chemical analysis of both unfermented and fermented products revealed an increase in protein, ash and fibre content while the lipid and carbohydrate content showed a decrease. The results indicated that fermentation resulted in protein enrichment of the fermented Icacinia manni mash. Fermentation was also observed to cause a marked decrease in the level of some toxic components (oxalic acid, phytic acid and hydrocyanic acid) of the product. The possibility of incorporating Icacinia manni among the edible starchy plant tubers is discussed.

Suitability of using sieved or unsieved maize mash for production of "OGI"--a fermented cereal food.

Proximate analysis of sieved and unsieved maize mash revealed that there was a decrease in the protein and lipid content of the sieved maize mash as compared to that of the unsieved maize mash. Crude fibre and ash was completely absent in the sieved maize mash, while they were present in the unsieved mash. Chemical analysis of the fermented unsieved maize mash revealed an increase in the protein content from 9.9% (unfermented) to 13.4% after 3 days of fermentation, whereas the protein content of the sieved maize mash increased from 7.1% (unfermented) to 8.4% after the same period of fermentation. Furthermore, the results revealed that the protein content of the fermented unsieved maize mash was 32.1% higher than that of the fermented sieved maize mash indicating that the unsieved maize mash was of a better nutrient quality and should be preferred to sieved maize mash for use in "Ogi" production.

Protein enrichment of lignocellulose resulting from the growth of two Streptomyces strains.

Two Streptomyces strains were grown on sugarcane bagasse and groundnut hulls lignocelluloses in semi-solid state culture at 37°C for 12 weeks. Best results gave a 45% depletion of sugarcane bagasse lignocellulose with a 21% crude protein content of final material. The possibility of using S. viridosporus to improve the protein content of both lignocelluloses for use as an animal feedstock supplement is discussed.

Enrichment of nutrient quality of cassava (Manihot esculenta Crantz) with microbial proteins.

The effect of fermentation on the nutrient quality of cassava was investigated. Chemical analysis revealed a general increase in ash, fibre and crude protein content of the fermented cassava mash, while the carbohydrate content showed a substantial decrease. The results of the chemical analysis indicated that fermentation resulted in a slight protein enrichment of the fermentated cassava mash. When active yeast cells were inoculated into the cassava mash before fermentation, the yeast cells grew and generated additional cell mass which was reflected in a higher content of crude protein in the fermented cassava mash. Results obtained also revealed that 3.3% concentration of yeast cell inoculum added to cassava mash before commencement of fermentation was optimum for maximal crude protein formation.

Study of the Bacillus flora of Nigerian spices.

Bacteriological examination of 230 samples of five different unprocessed spices (aligator pepper, red pepper, black pepper, thyme and curry powder) collected randomly from Port Harcourt main markets revealed that the spices were highly contaminated, with bacterial counts ranging from 1.8 x 10(4) to 1.1 x 10(8) per gram. Bacillus cereus was isolated in high numbers in the majority of the 230 samples examined. It was also observed that other Bacillus spp. including B. subtilis, B. polymyxa and B. coagulans occurred in significant numbers.

Incidence of Staphylococcus aureus, coliforms and antibiotic-resistant strains of Escherichia coli in rural water supplies in Port Harcourt.

The bacteriological quality of some rural water supplies in Port Harcourt was monitored over a 3 month period. The supplies were unsatisfactory as judged by standard plate counts (10(3)/ml) and the presence of presumptive and faecal coliforms and Staphylococcus aureus. The recovery of potentially pathogenic bacteria (e.g. Pseudomonas aeruginosa) further substantiated the existence of health hazards. The most frequently isolated coliforms were Escherichia coli, Enterobacter aerogenes and Klebsiella pneumoniae. Coliform contamination was greater in well water than in river or stream water samples. An antibiotic sensitivity test revealed that 17.5-27.2% of E. coli strains were resistant to three or more antibiotics. Escherichia coli isolated from well water samples exhibited the greatest degree of multiple resistance. Some strains were resistant to all the six antibiotics tested. The danger of an epidemic of waterborne diseases in the communities as a result of drinking water from these non-potable sources is noted.

Incidence of infantile diarrhoea due to enteropathogenic Escherichia coli in Port Harcourt metropolis.

Five hundred diarrhoeal stool samples from the University of Port Harcourt Teaching Hospital were investigated for enteropathogenic Escherichia coli. Results showed that the organism was endemic in Port Harcourt metropolis and was responsible for about 15% of the incidence of infantile diarrhoea in the community. Detailed analysis revealed that 13 serotypes were involved. It was also observed that babies aged between 0 and 18 months were more susceptible than those aged between 19 and 36 months. Male infants were also shown to be more at risk than females. Antibiotic sensitivity tests showed that the enteropathogenic E. coli isolated were highly resistant to most common antimicrobial drugs but were highly sensitive to genticin and cefotaxime.

Degradation of softwood, hardwood, and grass lignocelluloses by two streptomyces strains.

Two Streptomyces strains, S. viridosporus T7A and S. setonii 75Vi2, were grown on softwood, hardwood, and grass lignocelluloses, and lignocellulose decomposition was followed by monitoring substrate weight loss, lignin loss, and carbohydrate loss over time. Results showed that both Streptomyces strains substantially degraded both the lignin and the carbohydrate components of each lignocellulose; however, these actinomycetes were more efficient decomposers of grass lignocelluloses than of hardwood or softwood lignocelluloses. In particular, these Streptomyces strains were more efficient decomposers of grass lignins than of hardwood or softwood lignins.