Screening and Improvement of Local Isolates of Aspergillus Niger for Citric Acid Production

The study involved the screening of fourteen isolates of Aspergillus niger for citric acid production from glucose. The study was aimed at screening and improving local strains of Aspergillus niger with potential for citric acid production. All the isolates screened produced varying amounts of citric acid, the highest was by the isolate designated CP3 which produced 12.81g/l and the least was B11 and O12 which produced 3.42g/l all after 6 days of submerged fermentation. The isolate CP3 was chosen for further studies. Strain improvement studies which was based on exposure of CP3 to ultraviolet irradiation for 10, 30 and 45 minutes increased citric acid yield to 22.20g/l (48.89% increase) by mutant M45 followed by a citric acid yield of 16.22g/l by the 30 minutes mutant (M30) and the least being M10 which produced 13.66g/l in all cases after 6 days of fermentation. The mutant (M45) also yielded higher amount of citric acid (19.64g/l) without methanol as additive compared to the parent strain (CP3) which gave a citric acid of 14.94g/l with the addition of methanol after six days (144h) of fermentation in both cases. Finding from this study showed that all the isolates have potential for citric acid production.Keywords: Isolation, Screening, Improvement, Aspergillus niger, Citric aci

Seroprevalence of Human Herpes Virus 8 (HHV8) Infection among Commercial Sex Workers in Jos

A study of HHV8 seropositivity was conducted among commercial sex workers in Jos aimed at determining the prevalence in relation to history of STD, duration of prostitution, age and number of sexual partners per day. Antibodies to HHV8 were detected by enzyme linked - immunosorbent assay (ELISA) (Advanced biotechnologies Inc USA) in serum samples of 90 commercial sex workers, 41 (45%) of cases were positive for HHV8, 15 (17%) of the women were HIV Seropositive. Furthermore eight (8) among the HHV8 seropositive women were HIV seropositive given a co-infection rate of 20%. Of the risk factors evaluated, HIV seropositivity and history of sexually transmitted diseases were found to be significantly associated with HHV8 infection using chi’s square.( P < 0.05). However lack of condom use, number of sex partners and duration of prostitution were found not to be significantly associated with HHV8 infection using chi’s square. (P > 0.05.) we expect that this important seroepidemiologic baseline data will become a powerful tool for evaluating interventions and control measures

Occurrence of Listeria Monocytogenes in Irrigation Water and Vegetables at Jos, Plateau State, Nigeria

In this study, thirty water samples obtained from rivers, streams and ponds used for irrigation of vegetables at thirty different sites in Jos, Plateau state, Nigeria were analyzed for the presence Listeria monocytogenes and other Listeria species using the two-step enrichment method. Ten samples each spinach, lettuce and cabbage, which are common vegetables grown in Jos were analyzed for the presence of Listeria monocytogenes. The results obtained showed that out of the 30 water samples screened 10(33.3%) were positive for Listeria monocytogenes. Ponds accounted for 50% of the positive samples, followed by streams (33.3%) and rivers (27.2%). Of the ten samples of vegetables analyzed, only two spinach samples were positive for Listeria monocytogenes. Other bacteria species isolated from the water samples include L. onnocua, L. ivanovii. L. grayi, Bacillus spp, Streptococcus spp, Aeromonas spp, Pseudomonas spp, Klebsiella spp, Escherichia coli and Staphylococcus aureus. Dry season farmers and vegetables handlers in the irrigated fields should be educated on measures aimed at minimizing or eliminating the hazard associated with Listeria monocytogenes. Keywords: Farmers, vegetables, irrigation waters, bacteria, Listeria monocytogene

Optimization of Citric Acid Production through Manipulation of Cultural Conditions of Aspergillus Niger

An Aspergillus niger isolate was screened for citric acid production from glucose and the cultural conditions were manipulated for optimum citric acid production. Optimization studies improved citric acid yield by 13.34% from 12.81 g/l obtained during the screening test to 14.52 g/l obtained at the end of the optimization studies. Glucose concentration of 15%, pH of 5.5, methanol at 3% concentration (v/v) and agitation rate of 450 rpm were found to be more suitable for citric acid production by the Aspergillus niger isolate used in this studies. Keywords: Citric acid, Aspergillus niger, Submerged fermentation, cultural condition