S. P. Antai

Removal of Nigerian light crude oil in soil over a 12-month period

Abstract A study was carried out to aid in understanding the effect of various concentrations (10, 20, 30, 40% v/w) of Nigerian light crude oil (Transniger pipeline crude, TNP) deliberately spilled on soil will have on the indigenous bacterial population and the role of the bacteria in the removal of the oil. The average total counts of aerobic heterotrophs and crude oil utilizing bacteria in oil-impacted soils were 108 and 10 6 CFU/g , respectively, while in the untreated soil the total counts of the two groups of bacteria were low. The counts of the two groups of bacteria decreased with increasing oil concentration in the soil. Significantly higher numbers of total aerobic heterotrophs were recorded between May and July while those of crude oil utilizing bacteria were recorded between February and April probably due to differences in metabolic rates of the organisms as influenced by environmental conditions. The crude oil utilizing bacteria were identified as species of Bacillus, Pseudomonas, Vibrio, Micrococcus and Alcaligenes. The total extent of crude oil degradation by these organisms ranged from 26.7% to 43.3% after 16 days. GC analysis of the crude oil extracted from soil showed that hydrocarbon components C14 to C32 were extensively lowered in soil polluted with 10% and 20% (v/w) crude oil after 12 months but moderately lowered in soil treated with 30% (v/w) crude oil over the same period. In soil contaminated with 40% (v/w) of the same crude oil, minimal degradation of C14 to C32 was observed. The results indicate that the quantity of crude oil spilled in soil and the age of the contamination influence the rate and total extent of disappearance of the oil in the environment.

Utilization of cassava peels as substrate for crude protein formation.

Mash prepared from cassava peels was inoculated with eitherSacchromyces cerevisiae orCandida 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 °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.

Biodegradation of Bonny light crude oil by Bacillus sp and Pseudomonas sp

Abstract The effect of temperature, pH, nitrogen, and phosphorus concentrations on the biodegradation of Bonny light crude oil by Bacillus sp and Pseudomonas sp was studied. Results obtained revealed that 4 g/L of nitrogen and 3 g/L of phosphorus supported the highest level of crude oil degradation by Bacillus sp, while 3.5 g/L of nitrogen and 3 g/L of phosphorus was best for Pseudomonas sp. Temperature of 36 °C supported the highest level of crude oil degradation by the two organisms. The two organisms were, however, observed to be able to degrade crude oil efficiently over a wide range of temperature (20 ° to 44 °C). The pH of 7.4 was optimum for crude oil degradation by Bacillus sp whereas that of Pseudomonas sp was pH 7.0. Crude oil degradation by the two organisms under the conditions provided in this study indicates that the organisms are suitable candidates for application in oil spill clean up of the Nigerian terrestrial ecosystem.

Chemical changes during the fermentation of African locust-bean (Parkia filicoidea Welw) seeds for production of ‘Daddawa’

African locust-bean (Parkia filicoidea Welw) seeds were allowed to ferment under natural conditions and the chemical changes occurring during the fermentation were studied. Chemical analysis of fermented and unfermented beans showed a marked decrease in the total sugar content; crude and true protein levels all increased. The results of the chemical analyses indicate that fermentation resulted in protein enrichment of the fermented locust bean (‘daddaw’). Fermentation also imparts a characteristic flavour and odour to the beans.

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 acitve 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.

Lignocellulose degradation and crude protein formation by three ligninolytic Streptomyces strains

Streptomyces strains (11A, 21B and 31C) were grown on guinea grass lignocellulose and their ability to decompose lignocellulose was monitored. All three Streptomyces strains caused lignocellulose weight losses ranging from 27 to 34%. The three Streptomyces strains were also found to metabolize between 27 and 40% of the lignin component and 22–29% of the carbohydrate component of lignocellulose over the 12 week incubation period. Crude protein increases of degraded guinea grass lignocellulose were between 10–1 and 14–5% over the same period.

Microalgae biodiversity and biomass status in Qua Iboe Estuary mangrove swamp, Nigeria

Microalgae composition, abundance, diversity and biomass of the Qua Iboe Estuary mangrove swamp were studied. The results revealed the rich assemblage of the brackish ecosystem. Six major taxanomic classes were encountered. These were the Bacillariophyceae, Cyanophyceae, Chlorophyceae, Chrysophyceae, Euglenophyceae and Phaeophyceae. Their composition, abundance and diversity exhibits strong seasonal variation. Variations between pelagic and sedimentary habitats were also noticed. The diatoms (Bacillariophyceae) dominated the habitats. Actinoptychus undalatus, Navicula radiosa and Amphora ovalis co-dominated the pelagic water column; while the epipellic (intertidal) and benthic (subtidal) sediments were co-dominated by A. ovalis and Actinoptychus undulatus. Analyses of the Shannon’s index of general diversity (H1), McArthur-Terborgh species equitability index (E) and Simpson’s index of dominance (D) of the microalgae communities revealed that A. ovalis with a mean H1-value of 0.25, E-value of 0.08 and D-value of 0.05 was the most prevalent genus in the mangrove ecosystem despite its uneven distribution. The densities of the microalgae communities corresponded with their biomass statuses and were seriously impacted by oil spillage. This forms the basis of concern because the estuary is associated with a high probability of major oil pollution with serious consequences for ecological stability and fisheries.

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.

Seasonal dynamics of physicochemical properties and heavy metal burdens in Mangrove sediments and surface water of the brackish Qua Iboe Estuary, Nigeria

The physicochemical properties and concentrations of heavy metals were determined in surface water, intertidal mudflats (epipellic) and benthic sediments obtained from the mangrove swamp ecosystem of the Qua Iboe Estuary, Nigeria. The monthly concentrations of the nutritive salts revealed that the sediments are halomorphic. Heavy metal concentrations in benthic sediments and surface water were generally lower than the values recorded for the intertidal mudflats. The mean concentrations of heavy metals obtained from estuarine surface water and intertidal and subtidal sediments were highly variable and seasonally dependent. The levels of heavy metals in the intertidal sediments were comparatively higher in the wet than the dry season. The range of concentration over the months increased by 1.3% (Cr), 1.6% (Pb), 6.0% (V), 7.5% (Ni), 10.5% (Fe), 12.0% (Zn), and 15.0% (Cu). Cr, Pb, Zn, and V concentrations in intertidal and subtidal sediments were below the Sediment Quality Guidelines (SQGs). However, Cu and Ni concentrations exceeded these effect levels, indicating potential ecological effects on local benthic, pelagic and benthopelagic communities of the estuary. Linear relationships and coefficients for concentrations of heavy metals in surface water, intertidal and subtidal sediments during wet and dry seasons were calculated. Moreover, the results indicated a common anthropogenic pollution origin for the heavy metals.

Degradation of extractive-free lignocelluloses by Coriolus versicolor and Poria placenta

SummaryThe wood-decay fungi Coriolus versicolor, a white-rot fungus, and Poria placenta, a brown-rot fungus, were grown on an extractive-free lignocellulose prepared from quackgrass (Agropyron repens). Their abilities to decompose this lignocellulose were compared to their abilities to decompose softwood (Picea pungens) and hardwood (Acer rubrum) lignocelluloses. The two fungi were grown on malt-extract dampened lignocelluloses at 28°C for up to 12 weeks. Replicate cultures were periodically harvested and lignocellulose decomposition was followed by monitoring substrate weight loss, lignin loss, and carbohydrate loss. Coriolus versicolor decomposed the lignin and carbohydrate components of the grass lignocellulose as efficiently as the softwood and hardwood lignocelluloses. Poria placenta, however, was not an efficient degrader of either lignin or carbohydrate in the grass lignocellulose. Poria placenta readily decomposed carbohydrate components of the softwood lignocellulose but not the hardwood lignocellulose.