Aflatoxin-lysine adducts in blood serum of the Malawian rural population and aflatoxin contamination in foods (groundnuts, maize) in the corresponding areas

Aflatoxin-lysine (AFB₁-lys) adduct levels in blood samples collected from 230 individuals living in three districts of Malawi (Kasungu, Mchinji, and Nkhotakota) and aflatoxin B₁ (AFB₁) levels in groundnut and maize samples collected from their respective homesteads were determined using indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) methods. AFB₁-lys adducts were detected in 67% of blood samples, with a mean concentration of 20.5 ± 23.4 pg/mg of albumin. AFB₁ was detected in 91% of groundnut samples and in 70% of maize samples, with mean AFB₁ levels of 52.4 and 16.3 μg/kg, respectively. All participants of this study reported consuming maize on a daily basis and consuming groundnuts regularly (mean consumption frequency per week: 3.2 ± 1.7). According to regression analysis, a frequency of groundnut consumption of more than four times per week, being female, and being a farmer were significant (p < 0.05) contributors to elevated AFB₁-lys adduct levels in the blood. This is the first report on AFB₁-lys adducts in blood samples of residents in Malawi. The results reinforce the urgent need for interventions, aiming at a reduction of aflatoxin exposure of the population.

A Case for Regular Aflatoxin Monitoring in Peanut Butter in Sub-Saharan Africa: Lessons from a 3-Year Survey in Zambia

A 3-year comprehensive analysis of aflatoxin contamination in peanut butter was conducted in Zambia, sub-Saharan Africa. The study analyzed 954 containers of 24 local and imported peanut butter brands collected from shops in Chipata, Mambwe, Petauke, Katete, and Nyimba districts and also in Lusaka from 2012 to 2014. For analysis, a sample included six containers of a single brand, from the same processing batch number and the same shop. Each container was quantitatively analyzed for aflatoxin B1 (AFB1) in six replicates by using competitive enzyme-linked immunosorbent assay; thus, aflatoxin contamination level of a given sample was derived from an average of 36 test values. Results showed that 73% of the brands tested in 2012 were contaminated with AFB1 levels >20 μg/kg and ranged up to 130 μg/kg. In 2013, 80% of the brands were contaminated with AFB1 levels >20 μg/kg and ranged up to 10,740 μg/kg. Compared with brand data from 2012 and 2013, fewer brands in 2014, i.e., 53%, had aflatoxin B1 levels >20 μg/kg and ranged up to 1,000 μg/kg. Of the eight brands tested repeatedly across the 3-year period, none consistently averaged ≤20 μg/kg. Our survey clearly demonstrates the regular occurrence of high levels of AF B1 in peanut butter in Zambia. Considering that some of the brands tested originated from neighboring countries such as Malawi, Zimbabwe, and South Africa, the current findings provide a sub-Saharan regional perspective regarding the safety of peanut butter.

Simultaneous detection of groundnut rosette assistor virus (GRAV), groundnut rosette virus (GRV) and satellite RNA (satRNA) in groundnuts using multiplex RT-PCR

Groundnut rosette disease (GRD) is the most devastating disease of groundnuts in sub-Saharan Africa. The disease is caused by synergistic interactions between viruses and virus-like pathogens: groundnut rosette assistor virus (GRAV), groundnut rosette virus (GRV) and a satellite RNA (satRNA). The multi-pathogenic nature of GRD requires efficient diagnostic systems for plant breeding and pathology work. Currently, TAS-ELISA and RT-PCR are used to detect all three pathogens. This approach is time-consuming, expensive and not easily amenable to high throughput. A multiplex PCR-based approach was developed to detect all three pathogens at once, reducing diagnostics costs and time by two thirds. The technique is highly robust and amenable to high throughput, with sensitivity and specificity values of 88 % and 100 %, respectively. The positive predictive value for the technique is 100 %, and the negative predictive value is 90.6 %.

A Disease of Pearl Millet in Zimbabwe Caused by Pantoea agglomerans

Necrosis at the leaf tips and margins of pearl millet (Pennisetum glaucum (L.) R. Br.) was observed in 1995 in a Pseudomonas syringae resistance screening nursery near Bulawayo, Zimbabwe. Straw-colored lesions with a chlorotic edge often extended the leaf length, and were atypical of the round spots, with a brown margin, caused by P. syringae (1). Bacteria were isolated from cut lesions macerated in water by dilution streaking onto King's medium B and nutrient agar. A gram-negative, nonfluorescent, fermentative, rod-shaped bacterium, forming yellow colonies on nutrient agar was consistently observed. Three pots of 10, 2-to 3-week-old seedlings of a susceptible cultivar, 852B, were inoculated with a 10⁸ CFU per ml suspension from cultures by misting or injection into the whorl. In three experiments, the treatment and uninoculated control were incubated at 25°C and 95% relative humidity for 48 h before transfer to the greenhouse. The original symptoms of watersoaking at leaf tips and margins were observed after 4 days. Necrotic lesions surrounded by chlorotic tissue were observed a day later. Fluorescence on King's medium B, and levan, oxidase, potato-rot, arginine dihydrolase, 2-keto gluconate, nitrate reduction, gelatin, phenylalanine deaminase, and acid from starch tests were negative. Tobacco hypersensitivity, acid from sucrose and glycerol, aesculin hydrolysis, lipase, indole production, and growth on tetrazolium chloride were positive. The identification of the pathogen to the species level as Pantoea agglomerans (Ewing and Fife 1972) Gavini et al. 1989, formerly Erwinia herbicola, was by fatty acid analysis by the International Mycological Institute (Egham, Surrey, UK). P. agglomerans was recorded as a pathogen of pearl millet in India in 1958 (2). References: (1) G. N. Odvody and A. K. Vidaver. Sorghum Newsl. 23:134, 1980. (2) C. K. S. Rajagopalan and G. Rangaswami. Curr. Sci. 27:30, 1958.