Knockout and functional analysis of BSSS-related genes in Acremonium chrysogenum by novel episomal expression vector containing Cas9 and AMA1

A Paradigm of Computer Vision and Deep Learning Empowers the Strain Screening and Bioprocess Detection

High-performance strain and corresponding fermentation process are essential for achieving efficient biomanufacturing. However, conventional offline detection methods for products are cumbersome and less stable, hindering the "Test" module in the operation of "Design-Build-Test-Learn" cycle for strain screening and fermentation process optimization. This study proposed and validated an innovative research paradigm combining computer vision with deep learning to facilitate efficient strain selection and effective fermentation process optimization. A practical framework was developed for gentamicin C1a titer as a proof-of-concept, using computer vision to extract different color space components across various cultivation systems. Subsequently, by integrating data preprocessing with algorithm design, a prediction model was developed using 1D-CNN model with Z-score preprocessing, achieving a correlation coefficient (R2) of 0.9862 for gentamicin C1a. Furthermore, this model was successfully applied for high-yield strain screening and real-time monitoring of the fermentation process and extended to rapid detection of fluorescent protein expression in promoter library construction. The visual sensing research paradigm proposed in this study provides a theoretical framework and data support for the standardization and digital monitoring of color-changing bioprocesses.

Metarhizium anisopliae engineering mediated by a CRISPR/Cas9 recyclable system

The advent of CRISPR/Cas technology has revolutionized genome editing, offering simplicity, precision, and cost-effectiveness. While its application in biological control fungi has been limited, including the cosmopolitan fungus Metarhizium anisopliae, recent advancements show promise. However, integrating cas9 and selection-marker genes into fungal genomes poses challenges, including reduced efficiency, toxicity, and off-target effects. Besides, marker-free genetic engineering through a CRISPR recyclable system presents a viable solution, enabling efficient mutant generation without compromising fitness and virulence. This study pioneers the construction of marker-free strains of M. anisopliae using a CRISPR/Cas9 recyclable system. Precise deletion of albA and ku70, alongside gfp cassette insertion, confirms the system efficiency. This innovative approach holds significant potential for facilitating in-depth molecular studies, understanding their ecological roles in agricultural systems, and enhancing biocontrol efficacy against insect pests through genetic improvement.

Effect of catalase on CPC production during fermentation of Acremonium chrysogenum

Cephalosporin C (CPC) is a critical raw material for cephalosporin antibiotics produced by Acremonium chrysogenum. During fermentation, the oxygen supply is a crucial factor limiting the efficient biosynthesis of CPC. This study demonstrated that the addition of exogenous surfactants significantly increased the dissolved oxygen (DO) level, extracellular catalase content, and final CPC titer. Consequently, we hypothesized and examined a correlation between catalase and CPC biosynthesis in A. chrysogenum through both the exogenous addition of hydrogen peroxide (H₂O₂) and the endogenous modulation of the catA expression level. The results indicated that both the addition of H₂O₂ and the ∆catA mutation exhibited similar fermentation trends, leading to decreased extracellular catalase activity and increased intracellular reactive oxygen species (ROS) content, which resulted in reduced CPC production. Conversely, strains that overexpress varying levels of the catA accelerated hyphal differentiation under DO-limiting conditions, reducing intracellular ROS accumulation and decreasing cellular apoptosis, which stabilized CPC yield during the later stages of fermentation. This study provides a critical foundation for further investigations into the regulatory mechanisms governing CPC biosynthesis in A. chrysogenum.