Effects of carbon sources on pigment production by Talaromyces purpurogenus LC128689 in liquid surface cultures

A pigment producing fungus was isolated from soil collected from cassava processing site in Ebonyi State. The effects of carbon sources on pigment production by the isolate in liquid surface cultures were studied. Pigment production in a basal medium composed of (in g/L) MgSO4, 0.4; NaNO3, 0.8; peptone, 15 mixed with 12g/L of one of the following carbon sources: glucose, Ipomea batatas, Dioscorea alata, Manihot esculenta cratz, Colocasia esculenta flour or soluble starch, was investigated. The highest red, orange and yellow pigment concentrations were obtained with sweet potato and water yam flour, followed by soluble starch while the least pigment concentrations were obtained with glucose. Unit optical densities of red (13), orange (9.5) and yellow (11) pigments were produced by the fungus using Ipomea batatas flour. These were higher than the concentrations of red (9), orange (7) and yellow (10.5) produced from Hajjaj medium composed of (in g/L) Glucose, 50; monosodium glutamate, 12; K2HPO4, 2.5; KH2PO4, 2.5; MgSO4, 1; KCl, 0.5; ZnSO4, 0.001; FeSO4, 0.001; and MnSO4, 0.001. The results indicate that Ipomea batatas flour is a better carbon source than glucose for pigment production by T. purpurogenus and thus has a very high potential for commercial production of pigments.Keywords: Microbial pigments, natural colourants, carbon sources, sweet potato, T. purpurogenu

Economic feasibility of on-farm fuel ethanol production from cassava tubers in rural communities

A simple process for on-farm bioethanol production from cassava, using cassava koji supplemented with crude liquid enzyme and yeast was described. On a small scale, a fed-batch mode where 4 kg of koji, 2 kg of gelatinized cassava flour and 30 g of yeast cells were mixed and allowed to ferment for two days, followed by addition of 1.5 kg of cassava flour and fermenting for another three days, gave higher ethanol concentration of 7.05% (0.34 g-ethanol/g-cassava flour) than when 3.5 kg of gelatinized cassava flour, 4 kg of koji and 30 g of yeast cells were mixed at the same time and allowed to ferment for five days. The process was scaled up 100 times and economic feasibility was evaluated. The total investment cost was seven million, five hundred thousand Nigerian naira (₦) (US$46,875). With a payback period of five years, the cost of cassava tubers represented 71.73$0.641/l), which is not profitable considering the current market price of ethanol (US$0.597-0.748/l). The process becomes profitable only when the price of fresh cassava tuber is reduced to ₦5,000/ton (US$31.25/ton). At this price, the ethanol production cost would be ₦58.53/l (US$0.366/l). The process is recommended for vertically integrated system (on-farm process) where the cassava produced in the farm is used, thereby shielding it from high and fluctuating market prices of cassava.Keywords: Fuel ethanol, bioenergy, koji, economic analysis, cassava ethanolAfrican Journal of Biotechnology Vol. 12(37), pp. 5618-562

Antimicrobial activity of Xylopia aethiopica, Aframomum melegueta and Piper guineense ethanolic extracts and the potential of using Xylopia aethiopica to preserve fresh orange juice

Antimicrobial activity of ethanolic extracts of Xylopia aethiopica, Aframomum melegueta and Piper guineense fruits were assayed against fourteen (14) microorganisms commonly associated with foodpoisoning and/or food spoilage. The microorganisms were Bacillus subtilis IAM1069, Bacillus cereus IFO 13494, Staphylococcus aureus FDA 209p, Escherichia coli NRIC 1023, Salmonella typhimurium IFO12529, Lactobacillus plantarum IAM 1041, Pediococcus acidilactici-M, Leuconostoc mesenteroides- M, Lactobacillus casei TISTR390, Saccharomyces cerevisiae OC-2, Hansenula anomala IFO 0140 (p), Pichia memb.IFO 0128, Penicillium funiclosum NBRC 6345 and Candida species. All the plant extracts exhibited selective antimicrobial activities on the test organisms. X. aethiopica extract exhibited the highest antimicrobial activity on the organisms with a minimum inhibitory concentration (MIC) of 50 ppm on Bacillus species and S. aureus. S. cerevisiae (MIC = 300 ppm), P. funiclosum NBRC 6345 and L. mesenteroides (MIC = 500 ppm) were also susceptible to X. aethiopica fruit extract but the MIC values for the other tested microorganisms were higher than 1000 ppm. This was followed by A. melegueta fruit extract with MIC of 100 ppm for B. cereus and S. aureus. Although P. guineense fruit extract inhibited the growth of B. cereus and S. aureus (MIC = 300 ppm); and B. subtilis (MIC = 1000), the MIC for the other microorganisms were higher than 5000 ppm. On the whole, all the plant extracts exhibited the least antimicrobial activities on Lactobacilli and fungi species. X. aethiopica fruit extract was used to preserve fresh orange juice. The ability of 100 and 1000 ppm extract to preserve the orange juice was significantly greater (p<0.05) than 50 ppm. The microbial concentration in orange juice containing 100 ppm of X. aethiopica extract was 4 cfu/mL after 28 days of storage at room temperature.Keywords: Food spoilage, food poisoning, microorganisms, spices, ethanolic extract, natural preservatives, orange juiceAfrican Journal of Biotechnology Vol. 12(16), pp. 1993-199