The present invention belongs to the bioengineering field, and relates to a method for fermentation production of L-theanine by using an Escherichia coli genetically engineered bacterium. The engineered bacterium is obtained by serving a strain as an original strain, wherein the strain is obtained after performing a single copy of T7RNAP, a dual copy of gmas, xylR knockout, and sucCD knockout on an Escherichia coli W3110 genome, and by integrating genes xfp, pta, acs, gltA, and ppc, and knocking out ackA on the genome. The present invention has a high yield, and stable production performance; after 20-25 h, L-theanine has a titer of 75-80 g/L, and the yield is up to 52-55%. The fermentation broth is purified by membrane separation in combination with a cation-anion resin series technique. Moreover, the one-step crystallization yield is 72.3% and the L-theanine final product has a purity of 99%.

An engineered microorganism(s) with novel pathways for the conversion of short-chain hydrocarbons to fuels and chemicals (e.g. carboxylic acids, alcohols, hydrocarbons, and their alpha-, beta-, and omega-functionalized derivatives) is described. Key to this approach is the use of hydrocarbon activation enzymes able to overcome the high stability and low reactivity of hydrocarbon compounds through the cleavage of an inert CH bond. Oxygen-dependent or oxygen-independent activation enzymes can be exploited for this purpose, which when combined with appropriate pathways for the conversion of activated hydrocarbons to key metabolic intermediates, enables the generation of product precursors that can subsequently be converted to desired compounds through established pathways. These novel engineered microorganism(s) provide a route for the production of fuels and chemicals from short chain hydrocarbons such as methane, ethane, propane, butane, and pentane.

An engineered microorganism(s) with novel pathways for the conversion of short-chain hydrocarbons to fuels and chemicals (e.g. carboxylic acids, alcohols, hydrocarbons, and their alpha-, beta-, and omega-functionalized derivatives) is described. Key to this approach is the use of hydrocarbon activation enzymes able to overcome the high stability and low reactivity of hydrocarbon compounds through the cleavage of an inert CH bond. Oxygen-dependent or oxygen-independent activation enzymes can be exploited for this purpose, which when combined with appropriate pathways for the conversion of activated hydrocarbons to key metabolic intermediates, enables the generation of product precursors that can subsequently be converted to desired compounds through established pathways. These novel engineered microorganism(s) provide a route for the production of fuels and chemicals from short chain hydrocarbons such as methane, ethane, propane, butane, and pentane.

An engineered microbe that contains a designed platform for the conversion of one-carbon substrates to chemical products is described. The designed platform embodies a new metabolic architecture that consolidates carbon fixation, central metabolism, and product synthesis into a single pathway. This is made possible by the key finding that 2-hydroxyacyl-CoA lyase, an enzyme in the -oxidation pathway, is capable of catalyzing the CC bond formation between formyl-CoA and aldehydes of different chain lengths, allowing for the elongation of the carbon backbone of said aldehyde by one-carbon units. These novel microbes present an opportunity for the production of chemicals from single-carbon feedstocks such as carbon dioxide, carbon monoxide, formate, formaldehyde, methanol or methane.