Aflatoxins in aquatic species: metabolism, toxicity and perspectives

Abstract

Among all known mycotoxins, aflatoxins represent the most investigated, widespread and worrisome source of contamination of foods and feed worldwide. In the early 1960s, soon after the finding of aflatoxin B 1 (AFB 1 ) in the feedstuffs of aquacultured rainbow trout that had died in an epizootic of hepatomas, great scientific discoveries were made in several areas by a number of researchers under the direction of scientists like J. Halver, R. 0. Sinnhuber, G. S. Bailey, J. D. Hendricks and colleagues. Since that time, several studies have focused on the identification of new isoenzymes involved in AFB 1 metabolism and on the discovery of new modulators in AFB 1 -induced cancer initiation and progression. However, metabolic and toxicological studies on aflatoxins in marine aquacultured species are fragmented and restricted to a limited number of fish species. Aflatoxins exert a substantial impact on the fish farming production, causing disease with high mortality and a gradual decline of reared fish stock quality, thus representing a significant problem in aquaculture systems. Based on these considerations, the goals of this review article are: (1) to gather the currently available scientific information, summarising existing data on aflatoxin contamination on feeds and fishmeals, and toxicological effects induced in reared aquatic species; (2) to make a comparative analysis of AFB 1 metabolism in the most representative species studied; (3) to gain new insights on the risk of DNA damage caused by aflatoxins on fish genomes and their role in cancer development.

Effects of Toxin Binder Biotox on Growth Performance Survival, Enzymatic Activity, Hematologichal and Biochemical Parameters of Fingerlings Rainbow Trout (Oncorhynchus mykiss) Fed Diets- Contaminated with Aflatoxin

“…For example, rainbow trout is considered very susceptible to AFB1 [4,8]. The first documented incidences of aflatoxicosis affecting fish health occurred in the 1960s in trout hatcheries.…”

“…Although cottonseed meal is no longer used as a major ingredient in feed formulations, poor storage of other feed ingredients and nutritionally complete feeds can lead to contamination with aflatoxins [29,30]. Santacroce et al [8] explained that dosages of 0.5-1 AFB1 mg/kg feed resulted in 50% mortality. Other study showed that levels of 0.02 AFB1 mg /kg feed produced 96% incidence of liver tumors in rainbow trout.…”

“…The toxicity of aflatoxin also varies according to many nutritional factors, and recovery from protein malnutrition is delayed by exposure to aflatoxin [35]. Similary Santacroce et al [8] stated that the feeds containing 0.5-1 AFB1 mg/kg feed did not affect the growth, feed intake or produced liver damage on Baltic salmon. Another study reported that there were no differences in the evaluated growth performance and feed intake of juvenile salmon exposed to AFB1 doses 0, 1, 5, 10 or 20 mg/kg feed [9].…”

“…One of the most principal target organs for aflatoxicosis is hepatopancreas [8]. After the invasion of aflatoxin into the hepatopancreas, aflatoxin metabolites react negatively with different cell proteins, which lead to inhibition of carbohydrate, lipid metabolism and protein synthesis, finally inducing hepatopancreas necrosis, cell death or tumour.…”

“…These species specific differences can be attributed to differences in the metabolism of AFB1 in the liver and affinity of AFB1-derived metabolites to hepatic macromolecules [7]. The negative effcts of aflatoxin in different species such as Rainbow trout, Baltic salmon (Salmo salar), Nil tilapia (Oreochromis niloticus), coho salmon (Oncorhynchus kisutch), and Red Drum (Sciaenops ocellatus) [4,[8][9][10][11] and shrimp (Litopenaeus vannamei) have been demonstrated. There are a number of approaches that can be taken to protect of animal from toxic effect of aflatoxins and these involve prevention of fungal growth, and strategies to reduce or eliminate mycotoxins from contaminated feeds, such as physical, chemical, nutritional, and biological techniques [12].…”