NOVELTY - An isolated microorganism genetically modified to lack expression of a wild-type lactate dehydrogenase gene, where the microorganism can hydrolyze both C5 and C6 polysaccharides, is new.    USE - The microorganism is useful for hydrolyzing or saccharifying both C5 and C6 polysaccharides; direct fermentation of C5 and C6 carbohydrates; and for producing chemical product, where the product is an alcohol, preferably ethanol (all claimed).    ADVANTAGE - The invention provides microbial species that can consolidate the process of saccharification and fermentation in an efficient and cost-effective manner.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) an isolated microorganism selected from NRRL Accession No. NRRL B-50351, NRRL B-50352, NRRL B-50353, NRRL 8-50354, NRRL B-50355, NRRL B50356, NRRL 8-50357, NRRL B-50358, and NRRL B-50359;    (2) a isolated mesophilic microorganism that lacks lactate dehydrogenase activity, where the mesophilic microorganism ferments polysaccharides;    (3) an isolated mesophilic microorganism, genetically modified to produce higher amounts of ethanol, where the modification comprises inactivation of lactic acid synthesis as it occurs in the wild-type mesophilic microorganism;    (4) a product for production of a chemical product comprising: (a) a fermentation vessel comprising a carbonaceous biomass; and (b) microorganism genetically modified to inactivate a lactate dehydrogenase gene of the wild-type organism, where the microorganism hydrolyzes both C5 and C6 polysaccharides and produces a chemical product;    (5) a process for producing a chemical product comprising: (a) contacting a carbonaceous biomass with microorganism genetically modified to inactivate a lactate dehydrogenase gene of the wild-type organism, where the microorganism hydrolyzes both C5 and C6 polysaccharides; and (b) allowing sufficient time for the hydrolysis and fermentation to produce the chemical product;    (6) a chemical product produced by the process;    (7) an isolated microorganism that ferments cellulosic or lignocellulosic materials to produce ethanol in a concentration that is at least 90% of a theoretical yield, where the microorganism is genetically modified to inactivate a lactate dehydrogenase gene of the wild-type organism;    (8) a plasmid comprising fully defined 3255 bp (SEQ ID NO. 1) given in the specification; or a plasmid comprising a nucleic acid sequence with about 70% similarity to SEQ ID NO. 1; and    (9) a primer selected from gtatgattgttagcatttcaaatccag (SEQ ID NO. 2), ttgagccttttccagttaggatatg (SEQ ID NO. 3), gtttatcaattatcggggcttcc (SEQ ID NO. 4), and ccataacaagtagtacccttcactgataa (SEQ ID NO. 5); or a primer comprising a nucleic acid sequence with about 70% similarity to SEQ ID NO. 2-5.