Part Ⅱ Full Text Impact on metabolism and immune status from the effects of mycotoxins in poultry

摘要

Mycotoxins are secondary metabolites produced by certain species of fungi growing under specific environmental conditions. Primary metabolites are those produced by all fungi for both the synthesis of biomass and to generate the energy necessary for primary metabolism. In contrast, secondary metabolism is usually restricted to a small number of species (may be even strain specific) and it occurs mainly after a phase of balanced growth, usually associated with morphogenetic changes like sporulation. Secondary metabolites include pigments and compounds active against microorganisms (antibiotics), plants (phytotoxins) or animals/humans (mycotoxins). The biological role of secondary metabolism in fungi is still unknown.rnAccording to the moment when mycotoxigenic fungi contaminate the grain, two types of fungi can be recognized: those that preferentially infect stored grain (saprophytic) and those that attack the plant in the field (phytopathogenic). The most important species of saprophytic fungi are Aspergillus and Penicillium, while Fusarium spp. are the most relevant mycotoxigenic phytopathogens. It should be emphasized that not all strains of a particular species of fungus are capable of producing mycotoxins. Therefore, contamination of a given substrate with fungi does not necessarily imply mycotoxin contamination.