No abstract

Cordyceps militaris is a well-known edible medicinal mushroom in East Asia that contains abundant and diverse bioactive compounds. Since traditional genome editing systems in C. militaris were inefficient and complicated, here, we show that the codon-optimized cas9, which was used with the newly reported promoter Pcmlsm3 and terminator Tcmura3, was expressed. Furthermore, with the help of the negative selection marker ura3, a CRISPR-Cas9 system that included the Cas9 DNA endonuclease, RNA presynthesized in vitro and a single-strand DNA template efficiently generated site-specific deletion and insertion. This is the first report of a CRISPR-Cas9 system in C. militaris, and it could accelerate the genome reconstruction of C. militaris to meet the need for rapid development in the fungi industry.

jgjiang@scut.edu.cn.

In this research, a strain with broad-spectrum antimicrobial activities was isolated from the gastrointestinal tract of hairtail (Trichiurus haumela) and identified as Bacillus siamensis JFL15 through morphological, 16S rRNA, and average nucleotide identity analyses. The genome of B. siamensis JFL15 was sequenced, and three gene clusters involved in the biosynthesis of surfactin (srf), bacillibactin (dhb), and fengycin (fen) were predicted through antiSMASH analysis. The combined genomics-metabolics profiling of the strain revealed 20 active compounds, which belong to four main types of cyclic lipopeptides produced by Bacillus species: bacillibactin, iturin, fengycin, and surfactin. Among these lipopeptides, two high-purity antifungal components, namely, components b and c, were successfully identified as iturin A and bacillomycin F. The minimum inhibitory concentrations (MICs) of iturin A for Magnapothe grisea, Rhizoctorzia solani, and Colletotrichum gloeosporioides were 125.00, 62.50, and 125.00 μg/ml, respectively, whereas the MICs of bacillomycin F for these three organisms were 62.50, 31.25, and 62.50 μg/ml, respectively. The mechanism of bacillomycin F and iturin A against M. grisea was also investigated. Scanning electron microscopy (SEM) indicated that the surface of the hypha treated with iturin A or bacillomycin F became sunk, lumpy, and wrinkled. The diversity of the identified and predicted compounds from B. siamensis JFL15 suggested that this strain might be a promising biocontrol agent for an effective and environmentally friendly control of pathogenic microorganisms. To the best of our knowledge, this study is the first to describe cyclic lipopeptides purified and identified from B. siamensis.