Evolutionary engineering of Phaffia rhodozyma for astaxanthin-overproducing strain

Evolutionary engineering is a novel whole- genome wide engineering strategy inspired by natural evolution for strain improvement. Astaxanthin has been widely used in cosmetics, pharmaceutical and health care food due to its capability of quenching active oxygen. Strain improvement ofPhaffia rhodozyma, one of the main sources for natural astaxanthin, is of commercial interest for astaxanthin production. In this study a selection procedure was developed for adaptive evolution of P. rhodozyma strains under endogenetic selective pressure induced by additive in environmental niches. Six agents, which can induce active oxygen in cells, were added to the culture medium respectively to produce selective pressure in process of evolution. The initial strain, P. rhodozyma AS2-1557, was mutagenized to acquire the initial strain population, which was then cultivated for 550 h at selective pressure and the culture was transferred every 48h. Finally, six evolved strains were selected after 150 generations of evolution. The evolved strains produced up to 48.2% more astaxanthin than the initial strain. Our procedure may provide a promising alternative for improvement of highproduction strain.

CAM-BRAIN"ATR's ARTIFICIAL BRAIN PROJECT A Progress Report

This paper reports on progress made in the first 3 years of.ATR's 'CAM-Brain'Project, which aims to use 'evolutionary e.gi...,i.gi' techniques to build/grow/evolve a RAM-and-cellular-automata based artificial brain consisting of thousands of interconnected neural network modules inside special hardware such as MITs Cellular Automata Machine 'CAM-8,i, or NTT's Content Addressable Memory System 'CAM-System'. The states of a billion (later a trillion) 3D cellular automata cells, and edlions of cellular automata rules which govern their state changes, can be stored relatively cheaply in giga(tera)bytes of RAM. After 3 years work, the CA rules are almost ready. MITt,,'CAM-8' (essentially a serial device) can update 200,000,000 CA cells a second. It is possible that NTT's 'CAM-System' (essentially a massively parallel device) may be able to update a trillion CA cells a second. Hence all the ingredients will soon be ready to create a revolutionary new technology which will allow thousands of evolved neural network modules to be assembled into artificial brains. This in turn will probably create not only a new research field, but hopefully a whole new industry,namely 'brain building'. Building artificial brains with a billion neurons is the aim of ATR's 8 year i,CAM-B,ai.,' research project, ending in 2001.

Advances on systems metabolic engineering of Bacillus subtilis as a chassis cell

The Gram-positive model bacterium Bacillus subtilis,has been broadly applied in various fields because of its low pathogenicity and strong protein secretion ability,as well as its well-developed fermentation technology.B.subtilis is considered as an attractive host in the field of metabolic engineering,in particular for protein expression and secretion,so it has been well studied and applied in genetic engineering.In this review,we discussed why B.subtilis is a good chassis cell for metabolic engineering.We also summarized the latest research progress in systematic biology,synthetic biology and evolution-based engineering of B.subtilis,and showed systemic metabolic engineering expedite the harnessing B.subtilis for bioproduction.

Engineering of Saccharomyces cerevisiae for co-fermentation of glucose and xylose:Current state and perspectives

The use of non-food lignocellulosic biomass to produce ethanol fits into the strategy of a global circular economy with low dependence on fossil energy resources.Xylose is the second most abundant sugar in lignocellulosic hydrolysate,and its utilization in fermentation is a key issue in making the full use of raw plant materials for ethanol production and reduce production costs.Saccharomyces cerevisiae is the best ethanol producer but the organism is not a native xylose user.In recent years,great efforts have been made in the construction of xy-lose utilizing S.cerevisiae strains by metabolic and evolutionary engineering approaches.In addition,managing global transcriptional regulation works provides an effective means to increase the xylose utilization capacity of recombinant strains.Here we review the common strategies and research advances in the research field in order to facilitate the researches in xylose metabolism and xylose-based fermentation.