Visualisation and quantification of fumonisins bound by lactic acid bacteria isolates from traditional African maize-based fermented cereals, ogi and mahewu

ABSTRACT

Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (carcinogen; oesophageal cancer in Eastern Cape in South Africa). Lactic acid bacteria (LAB) have emerged as a promising natural detoxification agent against mycotoxins. The aim of this study was to visualise the interaction between fumonisins (FB₁ and FB₂) and LAB: Lactobacillus plantarum FS2, L. delbrueckii subsp. delbrueckii CIP 57.8T and Pediococcus pentosaceus D39, isolated from traditional fermented maize-based products (ogi and mahewu) using confocal laser scanning microscopy (CLSM) and to then quantify the LAB-bound fumonisin using high performance liquid chromatography (HPLC). The objective was to obtain a physically visible and quantifiable binding interaction between fumonisins and LAB strains with the aim of utilising LAB as a possible detoxifying agent. Fumonisins were derivatised using naphthalene-2,3-dicarboxaldehyde (NDA) and then combined with non-fluorescent LAB cells (viable and non-viable). For the quantification of bound fumonisins, viable and non-viable cells were incubated in the presence of predetermined concentrations of fumonisins and the level of fumonisin in the suspension was determined. CLSM showed the derivatised green fluorescent fumonisins binding to the surface of each of the LAB cells. For viable cells, L. plantarum FS2 bound FB₁ most effectively while P. pentosaceus D39 bound the least level of FB₁. The highest levels of FB₂ were bound by L. plantarum R 1096 and the least by L. delbrueckii CIP 57.8 T. For non-viable cells, L. plantarum FS2 was also the most effective for binding both fumonisins with P. pentosaceus D39 and L. delbrueckii CIP 57.8 T being the least effective for FB₁ and FB₂, respectively. To our knowledge, this is the first study to visualise the interaction between LAB and fumonisins. We demonstrate that LAB isolates from indigenous fermented maize-based beverages bind fumonisins and thus present a potential strategy for their reduction in these traditional foods.

KEYWORDS:

• Mycotoxins
• fumonisins
• fermented maize
• lactic acid bacteria
• non-viable cells

Acknowledgments

The authors would like to acknowledge and thank Mr. Alan Hall from the Laboratory for Microscopy and Microanalysis at University of Pretoria (UP) for his technical expertise with the Zeiss LSM 510 META confocal laser scanning microscope. This publication is resulting from a research project funded by the European Union (FP7 245-025) called African Food Revisited by Research (AFTER – http://www.afterfp7.eu/) and from a French-South African PHC Protea project (Project N° 29769VL). The views expressed are not necessarily those of the European Union.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the French-South African PHC Protea project [29769VL];African Food Revisited by Research [FP7 245–025];