The present disclosure relates to various different types of variants in E. coli coding and noncoding regions leading to enhanced lysine production for, e.g., supplements and nutraceuticals.

A method for producing ectoine by fermenting recombinant Corynebacterium glutamicum. The recombinant Corynebacterium glutamicum is obtained by overexpressing, in Corynebacterium glutamicum, an aspartokinase gene lysC of which feedback inhibition is relieved, then replacing the promoter of the dihydrodipicolinate synthase in the recombinant bacterium to attenuate the activity of the dihydropyrimidine dicarboxylic acid synthase, and then transforming the recombinant bacterium with the ectoine synthetic path related gene ectABC. The recombinant Corynebacterium glutamicum can be fermented using different cheap raw materials under a low salt condition to produce ectoine, and use cheap corn slurry instead of expensive yeast powder as a nutritional component, so as to further reduce the costs of the raw materials. In addition, the recombinant Corynebacterium glutamicum solves the biosafety problem, simplifies the post-extraction process, and has a good market application prospect.

Certain C. glutamicum strains overexpress genes coding for enzymes having the function of aspartate-semialdehyde dehydrogenase, aspartate aminotransferase, dihydrodipicolinate synthase, dihydrodipicolinate reductase, diaminopimelate decarboxylase, aspartatokinase and diaminopimelate dehydrogenase. The C. glutamicum strains also express NAD(P)(+) transhydrogenase subunit alpha PntA and NAD(P)(+) transhydrogenase subunit beta PntB of Corynebacterium urealyticum. A method is developed for the fermentative production of L-lysine using such C. glutamicum strains.

Methods for selecting a microbe for co-formulation with a carrier are provided. In some examples, the methods include identifying a microbe that comprises one or more dipicolinic acid (DPA) synthase genes, a microbe that expresses one or more DPA synthase proteins, and/or a microbe that produces DPA; and selecting the microbe for co-formulation with a carrier. The methods optionally include co-formulating the selected microbe with the carrier. In some examples, the methods include detecting one or more DPA synthase genes or one or more DpaA and/or DpaB proteins in a microbe. In other examples, the methods include detecting DPA in a microbe or medium containing a microbe, for example, utilizing a fluorescence assay. Microbial compositions including one or more microbes that comprise one or more DPA synthase genes, express one or more DPA synthase proteins and/or produce DPA are also provided.

The present invention relates to a recombinant microbial cell for producing at least one compound having structural Formula III from at least one simple carbon source:

##STR00001## wherein the simple carbon source is selected from the group consisting of glucose, sucrose, xylose, arabinose, mannose and glycerol; and wherein the cell comprises a further genetic modification to increase production of L-lysine in the cell from at least one of the simple carbon sources.

The present disclosure relates to a variant polypeptide having attenuated dihydrodipicolinate reductase activity and a method of producing L-threonine using the same.

The present disclosure relates to a modified polypeptide, in which the activity of meso-diaminopimelate is weakened, and a method for producing L-threonine using the same.