Single Cell Protein-State-of-the-Art, Industrial Landscape and Patents 2001-2016

Microbial Protein Produced from Brown Seaweed and Spruce Wood as a Feed Ingredient

The conversion of nonedible biomass to protein for use in feed is an attractive strategy toward improved sustainability in aquaculture. We have studied the possibility to produce protein-rich yeast Candida utilis on a medium consisting of enzymatically hydrolyzed sulphite-pulped spruce wood, mainly providing glucose, and enzymatically hydrolyzed brown seaweed, supplemented with ammonium sulfate. The results show that this blend constitutes a complete fermentation medium that enables good growth rates and cell yields. Results from a salmon feeding trial showed that the yeast can replace parts of a traditional fishmeal diet without harmful effects, although the apparent protein digestibility coefficient for the yeast was suboptimal. While further optimization of both the fermentation process and downstream processing is needed, the present proof-of-concept study shows a path to the production of microbial protein based on a simple, local and sustainable fermentation medium.

Microbial Methylotrophic Metabolism: Recent Metabolic Modeling Efforts and Their Applications In Industrial Biotechnology

Developing methylotrophic bacteria into cell factories that meet the chemical demand of the future could be both economical and environmentally friendly. Methane is not only an abundant, low-cost resource but also a potent greenhouse gas, the capture of which could help to reduce greenhouse gas emissions. Rational strain design workflows rely on the availability of carefully combined knowledge often in the form of genome-scale metabolic models to construct high-producer organisms. In this review, the authors present the most recent genome-scale metabolic models in aerobic methylotrophy and their applications. Further, the authors present models for the study of anaerobic methanotrophy through reverse methanogenesis and suggest organisms that may be of interest for expanding one-carbon industrial biotechnology. Metabolic models of methylotrophs are scarce, yet they are important first steps toward rational strain-design in these organisms.

Technologies for the bioconversion of methane into more valuable products

Methane, with a global warming potential twenty five times higher than that of CO₂ is the second most important greenhouse gas emitted nowadays. Its bioconversion into microbial molecules with a high retail value in the industry offers a potential cost-efficient and environmentally friendly solution for mitigating anthropogenic diluted CH₄-laden streams. Methane bio-refinery for the production of different compounds such as ectoine, feed proteins, biofuels, bioplastics and polysaccharides, apart from new bioproducts characteristic of methanotrophic bacteria, has been recently tested in discontinuous and continuous bioreactors with promising results. This review constitutes a critical discussion about the state-of-the-art of the potential and research niches of biotechnologies applied in a CH₄ biorefinery approach.