Biotechnology advances最新文献

The Ehrlich pathway is a catabolic process that imparts Saccharomyces cerevisiae and other yeasts with the ability to utilize branched-chain and aromatic amino acids as a source of nitrogen. Using this route, amino acids are transaminated to α-keto acids and the liberated ammonia is utilized for assimilatory reactions. This process leaves behind an array of aliphatic and aromatic carbon skeletons (fusel metabolites) that have found a multitude of uses in the production of flavors, chemicals, and pharmaceuticals. This review provides an update on the genetics and biochemistry of the Ehrlich pathway with an emphasis on the biotechnological valorization of fusel metabolites. We outline the impact of fusel metabolism on the organoleptic properties of fermented beverages and recap ongoing efforts to repurpose the Ehrlich pathway for production of advanced biofuels. We also highlight recent activity directed at producing opioids and other plant benzylisoquinolines, as well as engineering new-to-nature alkaloids by rewiring the yeast Ehrlich pathway. Collectively, these efforts have stimulated a deeper understanding of yeast fusel metabolism and opened new opportunities for biomanufacturing using conventional and non-conventional yeasts.

Bacillus is a ubiquitous genus renowned for its ability to form highly resilient spores, posing significant challenges to the food industry. As society progresses, the demand for high-quality food continues to rise. While reducing excessive processing helps maintain nutritional value and quality which fits the demands from consumers, it increases the risk of spore contamination. Germination-inactivation strategies offer a promising solution by converting spores into vegetative cells, which can be eliminated through milder treatments, thus preserving food quality while ensuring food safety. However, the limited efficiency of current methods to induce germination, particularly due to the emergence of super-dormant spores, hinders their widespread application. Optimizing spore germination is critical for the successful implementation of the germination-inactivation strategies. This study aims to provide a comprehensive overview of the mechanisms underlying Bacillus spore germination, focusing on the latest advances in signal transduction and macromolecular biosynthesis. Additionally, we systematically summarize the characteristics of super-dormant spores and their potential causes. Current methods for enhancing spore germination efficiency are thoroughly reviewed, and their limitations are discussed in detail. Based on these insights, innovative solutions are proposed to address the existing challenges. Recent research has unveiled the signal transduction mechanisms involved in spore germination, emphasizing the critical role of ion release. Moreover, transcription and translation likely govern dipicolinic acid release and cortex hydrolysis, respectively, with spores being able to rapidly initiate transcription through pre-located RNA polymerase. Interestingly, the emergence of super-dormant spores is influenced by both permanent and transient factors. To improve spore germination efficiency, promising solutions include innovative screening of germinants, optimization of the key factors of thermal activation and pressure-induced germination, and utilization of key substances during germination process.

The cell surface is extremely rich in multilayered information that exists in the form of complex monosaccharide assemblies, establishing a cellular sugar code. The sugar code is specifically deciphered by extracellular lectins, galectins, which are capable of recognizing sugar code components and transforming the code into precise cellular activities. Galectin-dependent reading of the sugar code relies on two major features: the specific recognition of sugars by the galectins' carbohydrate recognition domains (CRDs) and the modular architecture of galectins or their oligomerization. These two characteristics of galectins are essential for most of galectins' functions, as they ensure the specificity of sugar code recognition and permit multivalent interactions with carbohydrate ligands. The natural galectins are characterized by relatively fixed modular architecture, which allows for evolutionarily defined reading of the sugar code, limiting the spectrum of biological activities of galectins. Distinct protein engineering approaches, like linker modulation, crosslinking, domain swapping or fusion with oligomerization scaffolds allow for the modulation of galectin multivalency in order to overcome the natural decoding limitations of galectins and permit alternative reading of the sugar code. In this review, we we provide an overview of the architectures of engineered galectins with altered valency and discuss how alternative reading of the code by such proteins may prove beneficial in biotechnology.