Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya 320-8551, Japan.
Institute of Food Research, National Agriculture and Food Research Organization, 2-1-12 Kannon-dai, Tsukuba-shi 305-8642, Japan.
Toxins (Basel). 2024 Mar 8;16(3):141. doi: 10.3390/toxins16030141.
During an experiment where we were cultivating aflatoxigenic on peanuts, we accidentally discovered that a bacterium adhering to the peanut strongly inhibited aflatoxin (AF) production by . The bacterium, isolated and identified as , was found to produce an AF production inhibitor. Cyclo(l-Ala-Gly), isolated from the bacterial culture supernatant, was the main active component. The aflatoxin production-inhibitory activity of cyclo(l-Ala-Gly) has not been reported. Cyclo(l-Ala-Gly) inhibited AF production in without affecting its fungal growth in a liquid medium with stronger potency than cyclo(l-Ala-l-Pro). Cyclo(l-Ala-Gly) has the strongest AF production-inhibitory activity among known AF production-inhibitory diketopiperazines. Related compounds in which the methyl moiety in cyclo(l-Ala-Gly) is replaced by ethyl, propyl, or isopropyl have shown much stronger activity than cyclo(l-Ala-Gly). Cyclo(l-Ala-Gly) did not inhibit recombinant glutathione--transferase (GST) in , unlike (l-Ala-l-Pro), which showed that the inhibition of GST was not responsible for the AF production-inhibition of cyclo(l-Ala-Gly). When was cultured on peanuts dipped for a short period of time in a dilution series bacterial culture broth, AF production in the peanuts was strongly inhibited, even at a 1 × 10-fold dilution. This strong inhibitory activity suggests that the bacterium is a candidate for an effective biocontrol agent for AF control.
在一项培养产黄曲霉毒素花生的实验中，我们意外地发现，一种强烈附着在花生上的细菌强烈抑制了黄曲霉毒素（AF）的产生。该细菌被分离并鉴定为，发现它能产生一种 AF 产生抑制剂。从细菌培养物上清液中分离得到的环（Ala-Gly）是主要的活性成分。环（Ala-Gly）抑制黄曲霉毒素产生的活性尚未报道。环（Ala-Gly）在液体培养基中抑制 AF 产生的活性比环（Ala-l-Pro）更强，而不影响其真菌生长。在已知的 AF 产生抑制剂二酮哌嗪中，环（Ala-Gly）具有最强的 AF 产生抑制活性。环（Ala-Gly）中甲基部分被乙基、丙基或异丙基取代的相关化合物的活性比环（Ala-Gly）强得多。环（Ala-Gly）不像（Ala-l-Pro）那样抑制 GST，表明 GST 的抑制不是环（Ala-Gly）抑制 AF 产生的原因。当在短时间浸泡在一系列细菌培养液稀释液中的花生上培养时，花生中的 AF 产生受到强烈抑制，即使在 1 × 10 倍稀释时也是如此。这种强烈的抑制活性表明，该细菌是一种有效的 AF 控制生物防治剂的候选物。
