TOXIGENIC MYCOFLORA AND AFLATOXINS PRODUCTION ABILITY IN FEED INTENDED FOR BREEDING CHINCHILLA

LANDA FLORENCIA; GONZALEZ PEREYRA MARIA LAURA; PENA GABRIELA; CAVAGLIERI LILIA; DALCERO ANA; ROSA CARLOS; MAGNOLI CARINA

Congreso; VI Latinoamerican Congress of Mycotoxins; 2010

Background. Mycotoxins are secondary metabolites secreted by fungi, mostly belonging to the genera Aspergillus spp., Penicillium spp. and Fusarium spp. They are produced in cereal grains as well as forages before, during and after harvest, in various environmental conditions. Due to the diversity of their toxic effects and their synergetic properties, mycotoxins are considered as risky to the consumers of contaminated foods. The presence of mycotoxins in feeds may decrease the feed intake and affect animal performance. Aflatoxins (AF) are a group of naturally occurring mycotoxins produced by Aspergillus species, especially A. flavus and A. parasiticus, which grow in a wide variety of improperly stored food commodities (Guengerich et al., 1998). Chinchillas (Chinchilla lanigera) are rabbit-sized crepuscular rodents native to the Andes Mountains in South America. They are farm raised and are currently used by the fur industry and as pets. The growing international demand for chinchilla fur makes the breeding of these animals a highly profitable activity in Argentina. Cases of acute aflatoxicosis have been reported worldwide in dogs, pigs, or cattle that consume naturally contaminated feed (CAST 2003; GMP 2005). Although chinchillas are known to be very sensitive to mycotoxins, few data about acute toxicosis have been reported (González Pereyra et al, 2008). The aims of present study were 1) to isolate and identify potential mycotoxicogenic mycobiota from chinchilla feeds and, 2) to determine the aflatoxigenic ability of isolated Aspergillus section Flavi.Materials and Methods. A total of twenty feedstuff samples were collected from one factory (A) and one farm (B) during 6 months (10 samples from each place), located in Río Cuarto Córdoba. Three subsamples from different portions of each feedstuff bags to make representative laboratory samples were taken. Twenty grams of each milled sample were blended with 180 ml of peptone water 0.1% (w/v), diluted to final concentration of 10-1, 10-2 and 10-3 and then, an aliquot was inoculated in triplicate on to Dichloran Rose Bengal Chloramphenicol agar (DRBC) and Dichloran 18% Glycerol agar (DG18). Plates were incubated at 28°C for a week. At the last day of incubation, Aspergillus and Fusarium colonies were picked and transferred to malt extract agar (MEA) and Nash?Snyder agar slants, respectively. They were allowed to grow at 28°C for 7 days for identification to species level. Identification for Aspergillus and Fusarium species was made according to macroscopic and microscope observation criteria in accordance with Klich (2002), and Nelson et al. (1983), respectively. Aflatoxin B1 production ability was performed according to Geisen (1996).Results and Discussion. Total feed mycobiota counts in farm were between 1.5 x 102 and 1.7 x 104 CFU/g in DRBC and 2 x 102 and 1 x104 CFU/g in DG18 for feedstuff A and between 1 x 102 and 3 x 103 CFU/g in DRBC and 1 x 102 and 7 x 103 CFU/g for feedstuff B. Counts from the factory samples were between1 x 102 and 2.5 x 103 CFU/ g in DRBC and 2 x 102 and 2 x 103 CFU/g in DG18 for feed A and between 2 x 102 and 2.8 x 103 CFU/g in DRBC and 7 x 102 and 7 x 103 CFU/ g in DG18 for feed B. Highest CFU counts were obtained from the feedstuff A (farm), which was over the recommended limit established by Good Manufacturing Practices (GMP, 2008). Mycological examination of different kinds of feeds indicated that Fusarium was the prevalent genus in feeds from farm and F. verticillioides and F. proliferatum were the most frequent isolated species. Prevalent genera and species were Aspergillus and Fusarium, and A. flavus and F. verticillioides for feed A and B, respectively. Penicillium was also present in all analyzed samples and it achieved a high isolation percentage. In the present study, the occurrence of the main toxigenic genera (Aspergillus, Fusarium and Penicillium) showed a potential risk of mycotoxins contamination. Some of the analyzed samples indicated the presence of AFB1 and 46% of A. flavus strains were able to produce AFB1 with levels that varied from 0.66 to 49.25 μg/g.Conclusion. Feed samples containing toxigenic species and AFB1 are potentially toxic for animals as chinchillas.References.Council for Agricultural Science and Technology (CAST): 2003, Mycotoxins: risks in plants animal and human systems. Task Force Report No. 139. CAST, Ames, IA.Geisen, R. 1996. Multiplex polymerase chain reaction for the detection of potential aflatoxin and sterigmatocystin producing fungi. Syst. Applied Microbiol., 19: 388-392,Gonzalez Pereyra M. L., Carvalho E., Tissera J., Keller K. M., Magnoli C., Rosa C.A.R., Dalcero A. M., Cavaglieri L. R. 2008. An outbreak of acute aflatoxicosis on a chinchilla (Chinchilla lanigera) farm in Argentina. Journal of Veterinary Diagnostic Investigation, 6: 853-856.Guengerich F. P., Johnson W. W., Shimada T., 1998. Activation and detoxification of aflatoxin B1. Mutat Res. 402:121?128.Klich, M. A. 2002. Identification of Common Aspergillus Species. CSIRO Division of Food Processing, North Ryde, p.116.Good Manufacturing Practice (GMP): 2005, GMP 14: Regulations on product standards in the animal feed sector. Series I: Basic regulation, standards and conditions.