Nuria Sala

Fumonisins B1 and B2 and toxigenic Fusarium strains in feeds from the Spanish market

Natural occurrence of fumonisins B1 and B2, incidence of Fusarium species, and capacity to produce fumonisins by Fusarium isolates, were investigated in 50 corn-based samples from Spain destined for animal consumption. Forty-four samples (88%) were found to be contaminated with fumonisins. The levels of contamination were very low, with a mean of 400 ng/g in the samples. We investigated the capacity of 11 isolates of Fusarium moniliforme and 19 isolates of F. proliferatum to produce fumonisins. All F. proliferatum isolates and 8 out of the 11 F. moniliforme isolates assayed produced fumonisins on a corn medium. The FB1/FB2 ratio in the isolates ranged from 1.1 to 3.5.

Fumonisin producing capacity of Fusarium strains isolated from cereals in Spain

A total of 147 Fusarium spp., predominantly from the section Liseola were isolated from cereals in Catalonia, Spain. Fusarium moniliforme was the predominant species (85.7%) isolated from these grains. Other species·included Fusarium sporotrichoides , Fusarium heterosporum , Fusarium tricinctum , Fusarium poae , Fusarium anthophilum and Fusarium subglutinans . The ability of these isolates and species to produce fumonisin B1 and B2 was assessed on moist sterile corn. This showed that about 34% of the strains from the section Liseola produced both fumonisin B1 and B2 although the quantities varied considerably. One isolate of F. subglutinans was demonstrated to produce both fumonisin B1 and B2.

Fate of fumonisins b1 and b2 in steeped corn kernels

Corn kernels naturally contaminated with fumonisins B1 and B2 were steeped by dipping the whole kernels in either water or a 0.3% solution of sodium bisulphite (pH = 5.7) for 6, 12, 24, 36 and 48 h. The toxin content of both the solid and the liquid were analysed for each time period. A different rate of interchange between the solid matrix and the water solution was found for FB1 and FB2 and some differences were found in the fate of both fumonisins between the two steeping systems studied. In addition, a preliminary study of the distribution of FB1 and FB2 between the germ and the remaining part of the kernel was carried out.

Bactericidal and fungicidal activity of Aspergillus ochraceus metabolites and some derivatives

The bactericidal and fungicidal activities of aspyrone and asperlactone, secondary metabolites of Aspergillus ochraceus, and some aspyrone derivatives were studied. In general, aspyrone exhibited better activity than asperlactone or aspyrone derivatives. The inhibition patterns of the assayed compounds were different. Helminthosporium monoceras was the tested mould most inhibited by the studied compounds. The comparative study of the activity of the different compounds showed that the epoxy group seems to be necessary for activity against some micro-organisms.

Preparation of (S)-1-Halo-2-octanols Using Ionic Liquids and Biocatalysts

Preparation of (S)-1-chloro-2-octanol and (S)-1-bromo-2-octanol was carried out by the enzymatic hydrolysis of halohydrin palmitates using biocatalysts. Halohydrin palmitates were prepared by various methods from palmitic acid and 1,2-octanediol. A tandem hydrolysis was carried out using lipases from Candida antarctica (Novozym® 435), Rhizomucor miehei (Lipozyme IM), and “resting cells” from a Rhizopus oryzae strain that was not mycotoxigenic. The influence of the enzyme and the reaction medium on the selective hydrolysis of isomeric mixtures of halohydrin esters is described. Novozym® 435 allowed preparation of (S)-1-chloro-2-octanol and (S)-1-bromo-2-octanol after 1–3 h of reaction at 40 °C in [BMIM][PF6].

A Survey of aflatoxins and aflatoxigenic Aspergillus flavus in corn-based products from the Spanish market

The natural occurrence of aflatoxins B1, B2, G1 and G2, incidence of Aspergillus flavus, and capacity to produce aflatoxins by A. flavus isolates, were investigated in 100 corn-based samples from Spain destined for human and animal consumption. Only one sample for animal consumption and none for human consumption were found to be contaminated with aflatoxins B1 and B2. The levels of contamination were 0.15 micrograms/g of B1 and 0.08 micrograms/g of B2. Of 43 isolate of A. flavus, only 4 were aflatoxin producers.

Preparation of chiral glycerol derivatives using chemoenzymatic approaches

Following our preparation of dissymmetric chlorohydrin esters from glycerol, we have used several lipases and whole cells to examine the kinetic resolution (KR) and dynamic kinetic resolution (DKR) of 3-chloro-2-hydroxypropyl esters. Regarding the KR, PS-IM, MmL and CALB lipases and whole cells of Aspergillus flavus showed the best selectivity and activity, depending on the compound studied. PS-IM allowed the isolation of (R)-3-chloro-2-hydroxypropyl pivaloate in 34% yield and with >99% enantiomeric excess (ee). DKR was carried out combining the biocatalysts that performed best for KR and suitable reaction conditions for racemization. Whole cells of A. flavus allowed the preparation of enantioenriched (S)-3-chloro-2-acetoxypropyl-2-methyl-2-phenyl propanoate in 43% yield and with 79% ee. Lipozyme from Mucor miehei used in a reaction subsequent to DKR allowed the purification of the corresponding enantioenriched (S)-3-chloro-2-acetoxypropyl pivaloate.

Linking extraction and purification of maize samples for fumonisin analysis.

Fumonisins are produced by several fungal species that are common contaminants of maize. The most abundant naturally occurring fumonisin, fumonisin B1 (FB1), has been shown to induce several animal disease syndromes. The development of analytical methods is therefore important. A new method is described that integrates extraction and purification of maize samples in one step. It efficiency is compared against well-known methods, and shows similar results for naturally contaminated maize. It is concluded that the proposed method can be applied to fumonisin B1 and fumonisin B2 (FB2) analysis in maize at least within the concentration range found.