Microbiological and molecular determination of mycobiota in fresh and ensiled maize silage

Abstract

The mycobiota of fresh and ensiled maize was studied with culturing techniques and a DNA sequence-based approach. Freshly chopped and ensiled maize were collected for 2 y from 12 farms in Pennsylvania. Samples were plated on selective media and isolates identified by morphology and sequences of the internal transcribed spacer regions of rDNA, 800-900 bp of the 5' end of the translation elongation factor 1-alpha gene and a portion of the rodA gene (Aspergillus fumigatus only). ITS regions were amplified from total silage DNA, cloned, sequenced and compared to fungal ITS sequences in GenBank with the BLAST-N algorithm. For samples analyzed by both methods, the molecular technique detected a greater number of species than selective plating. Plating recovered several Penicillium and Fusarium species and Aspergillus fumigatus, while molecular analysis detected Alternaria, Penicillium and Fusarium species. Data from both methods found that Fusarium and Penicillium were the dominant mycotoxigenic fungi in silage, while yeast made up the majority all fungi recovered or detected. Known mycotoxigenic species often accounted for 50% or more of the total number of species isolated or detected at each site. Viable Fusaria were not isolated from or detected in ensiled maize, suggesting that Fusarium species do not survive the ensiling process. Results from this study suggest that given the numerous species of fungi present in silage with mycotoxin producing ability, there is a strong possibility that silage may be contaminated with multiple toxins simultaneously.

Survey of Fungal Diversity in Silages Supplied to Dairy Cattle in Belgium Over a Two-Year Period

“…The most frequently isolated Penicillium in silages were species from the P. roqueforti group, which was divided into three species, P. roqueforti, P. paneum and P. carneum, based on analysis of rDNA genes and chemotaxonomic profiles (Boysen et al, 2000). In agreement with other studies on the P. roqueforti group (Boysen et al, 2000;Garon et al, 2006;O'Brien et al, 2007;Mansfield and Kuldau, 2007;Richard et al, 2007) only P. roqueforti and P. paneum were isolated from silages. In the present study, Penicillium species encountered most frequently were P. roqueforti or P. paneum depending on the year of sampling and the type of forage crop.…”

“…The isolation of P. roqueforti and P. paneum was expected because their ability to survive under silage conditions is well documented (Auerbach et al, 1998, Boysen et al, 2000, Mansfield and Kuldau, 2007. Members of the P. roqueforti group are unique in their high tolerance to low pH, often in conjunction with organic acids, and to high CO 2 and to low O 2 content in the environment (Samson and Frisvad, 2004).…”

Fusarium and Aspergillus mycotoxins effects on dairy cow health, performance and the efficacy of Anti-Mycotoxin Additive

“…Mycotoxins can also be present in hay, straw and silage after a prolonged period of storage (Mansfield and Kuldau 2007). A high dry matter concentration (>50%) in the raw material makes silage more susceptible to self-heating and infestations with toxin-producing fungi (Purwin et.…”

Mycotoxins in cattle feeds and carry-over to dairy milk: A review

“…The third source of mycotoxins in the diet of dairy cows results from the consumption of preserved feeding stuffs such as silage, hay, and straw (O'Brien et al 2005;Mansfield and Kuldau 2007). Particularly after a longer storage period, silage can be spoiled by a variety of fungal species, which are acid-tolerant and micro-aerobe.…”