Hester Vismer

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Walter Wymer

University of Lethbridge

Ekrem BAHCEKAPILI

Karadeniz Technical University

Susana Nila-Enríquez

Tecnológico de Monterrey

Ramjit Singh

Central University Of Kashmir

Arturo Vega

Newcastle University

Prof. Haitham Alshibly

Al-Balqa Applied University

Dr. Ahmed A B D I R A H M A N Herzi ( PhD)

SOAS University of London

Zaid Halhouli

UPM - Universiti Putra Malaysia

stephen E hiamey

University Of Cape Coast, Ghana

Josip Mikulic

Faculty of Economics, University of Zagreb

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Papers by Hester Vismer

Effect of Bt corn hybrids on insect damage, incidence of fumonisin-producing Fusarium species and fumonisin levels in South Africa

Phytopathology, Jun 1, 2005

Field trials were conducted over two seasons at two locations, Potchefstroom and Vaalharts, in So... more Field trials were conducted over two seasons at two locations, Potchefstroom and Vaalharts, in South Africa. Three Bt and three non-Bt corn hybrids were planted and the ears either mechanically wounded or left untreated. Yield and moisture content: no significant differences. Visible stalkborer damage: significantly lower in CRN 4549Bt (wounded) at Potchefstroom, and in CRN 4549Bt (untreated) and CRN 4160Bt (wounded) at Vaalharts, compared to non-Bt hybrids for the wounded and untreated ears, second season. Visible ...

Presence of pathogenic cryptococci on trees situated in two recreational areas in South Africa

Fungal Ecology

Abstract Knowledge of the environmental prevalence of members of the Cryptococcus neoformans/Cryp... more Abstract Knowledge of the environmental prevalence of members of the Cryptococcus neoformans/Cryptococcus gattii species complex is important, since cryptococcal infection is acquired from the environment. We determined whether trees located in two South African recreational areas harboured pathogenic cryptococci and compared the isolates to clinical isolates obtained from Western Cape hospitals with molecular typing techniques. The majority of isolates originating from trees in a public park in Cape Town (PPCT) were C. gattii sensu stricto, followed by C. neoformans sensu stricto genotype AFLP1/VNI. The PPCT trees might be a source of infection, since all genotype AFLP1/VNI isolates from these trees and one clinical isolate belonged to the same sequence type (ST), i.e. ST23. Recombination and basidiospore production might be occurring in PPCT trees that contained C. gattii s.s. isolates belonging to both mating types. The presence of C. gattii s.s. in PPCT trees might therefore pose a risk to human health.

The growth of Cryptococcus gattii MATα and MATa strains is affected by the chemical composition of their woody debris substrate

Fungal Ecology

Chemoprofiling Of Mycotoxigenic Fungi Occurring In Maize, Sorghum And Millet Grains In Africa

Qscience Proceedings, May 21, 2012

Sorghum (Sorghum bicolor (L.) Moench) and pearl millet (Pennisetum glaucum (L.) R.Br) are indigen... more Sorghum (Sorghum bicolor (L.) Moench) and pearl millet (Pennisetum glaucum (L.) R.Br) are indigenous crops to the African continent. Apart from maize, rice and wheat, these crops are basic staple foods for many rural communities in Africa. The growth and production of these grains can be negatively affected by plant diseases caused by diverse fungal genera. The ability of Fusarium species to produce mycotoxins, including fumonisins (FUM) and moniliformin (MON), that have detrimental health effects for both humans and animals make it important to evaluate their toxin production in crops that are intended for human consumption. Fusarium species occur naturally in maize, sorghum and millet, among other grains. Potentially toxigenic species isolated from grain samples from Nigeria harboured high FUM and MON producing strains. This was confirmed by molecular identification and by chemoprofiling in in vitro grain cultures. Mycotoxin levels of Fusarium species grown on maize patty cultures were compared to levels produced on sorghum and millet patty cultures. FUM and MON profiles of 18 Fusarium proliferatum and two other Fusarium control strains, i.e. high producers of either one of these toxins, were analyzed. FUM (fumonisin B1, B2 and B3) were extracted with methanol/water and MON with acetonitrile/water. The mycotoxin extracts were cleaned up using strong anion exchange solid phase extraction prior to quantification by reversed-phase HPLC. Results indicated that under conducive conditions, all the strains tested produced FUM, some in relatively large quantities (11/18), ranging from 694-17421 mg/kg culture material. For 8/18 strains the MON levels were >500 mg/kg and up to 8892 mg/kg culture material. Although there are variations in the potential or ability of F. proliferatum isolates to produce either FUM or MON, these fungi can use several grains as a source for toxin production irrespective of their original hosts. This study gives insight into the potential and ability of Fusarium species, isolated from maize, sorghum and millet, to produce mycotoxins on several grain sources, which may have a marked influence on food safety and security, and the potential health risk they hold for many rural communities in Africa.

Hester Vismer

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