Prevalence of toxigenic mycobiota and mycotoxins in date palm fruits and investigation on Bacillus cereus 342-2 as biocontrol agent

Date palm fruit is consumed as a highly nutritious food item particularly in the Middle East. This work was designed to investigate the occurrence of filamentous moulds, their toxins in date palm fruit samples, and explore the biocontrol potential of Bacillus cereus 342-2 against few date palms associated fungal species. In total, 36 date palm fruit samples from different sources and varieties were collected from the markets in Qatar. Aspergillus and Penicillium spp. were found to contaminate most of the samples, except Akhlas samples, which were free of any fungal contamination. In total, ochratoxin A (OTA) was found in 6 (16.67%) date samples, all within the permissible limit, except one (2.7%), where the level was above the maximum permissible concentrations of 2 µg/kg. The volatile organic compounds (VOCs) of B. cereus were very effective against the growth of A. niger and A. carbonarius with an inhibition rate of 100%. Whereas their effects against A. flavus was weak as mycelia grew; however, no sporulation occurred until day 7 of co-incubation. Gas chromatography mass spectrophotometry analysis of B. cereus volatiles showed aldehyde as a major component with a peak area of 10.6%, and Undecane with a peak area of 2.02%. The inhibitory effect of VOCs was either from aldehyde alone, or a synergetic effect of the two molecules.