2890 is indeed A. flavus (see Additional files 1 2 3 and 4). It is very likely that the strain we used belongs to the type IV A. flavus, which produces both AFBs and AFGs, as reported recently . The time course of AF production To AZD6244 cost assess the production and possible degradation of AFs during the cultural period with various initial spore densities, we examined AFG1 contents in the PMS medium during a five-day culture period, with 106 or 104 spores/ml. We observed that, in the culture initiated with 104 spores/ml, a significant amount of AFG1 was detected on the day two, reached the maximum level on the day three, and subsequently decreased gradually. In contrast, almost no AFs were detected in the culture
A-769662 price initiated with 106 spores/ml during the entire five-day culture period (Figure 1E). It has been shown previously that peptone from different suppliers may induce different enzyme activities in Candida albicans. The peptone initially used in this study selleck chemicals was purchased from Beijing Aoboxing Biotech.
To ensure the result observed is a general phenomenon, peptone from Sigma and Shuangxuan Microbe Culture Medium Products Factory was tested, and same results were observed (see Additional file 5). To examine if cultures with high initial spore densities lead to a similar AF accumulation in mycelia, we used the TLC method to analyze AF contents in mycelia cultured for three days in either PMS or GMS media, with 104 or 106 spores/ml. The results showed greatly reduced AF content in mycelia in culture initiated with 106 spores/ml, similar
to the AF content of the media. In contrast, increased AF production was observed in mycelia cultured in GMS media with 106 spores/ml, as compared to that with 104 spores/ml (see Additional file 6). High initial spore density in PMS media led to rapid mycelial growth To exclude the possibility that the reduced AF production in PMS media initiated with high initial spore densities was caused by inhibited fungal growth, mycelium dry weights were determined during a five-day culture period. A. flavus cultured in GMS media with Selleck Rucaparib an initial density of 104 or 106 spores/ml showed a similar growth curve, with a continuous increase in dry weight during the five-day incubation. Higher initial spore density led to slightly faster mycelial growth, and an increased mycelium dry weight (Figure 2A). A. flavus cultured with 104 spores/ml in PMS media showed a similar growth curve to that in GMS media with the same spore density (Figure 2B). However, a much sharper exponential growth phase was observed in the first two days in PMS culture initiated with 106 spores/ml (Figure 2B). The mycelium dry weight reached the maximum level on the 4th day and decreased significantly afterwards, suggesting no inhibition of growth in the high density PMS culture. Instead, A. flavus cultured in PMS media with a high initial spore density grew faster and degenerated earlier (Figure 2B).