NOVELTY - Method for producing product involves (a) treating reduced recalcitrance lignocellulosic or cellulosic material with one or more enzymes and/or organisms to produce polycarboxylic acid, and converting the polycarboxylic acid to the product, (b) contacting mixed sugar solution comprising nitrogen source and inorganic salts with succinic acid producing organism to produce succinic acid, purifying the succinic acid, and converting the purified succinic acid to the product, where the sugar solution is prepared by saccharifying electron beam treated e.g. cellulosic biomass.    USE - The method is useful for producing product, preferably polycarboxylic acid chosen from oxalic acid, malonic acid, succinic acid, tartaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, maleic acid, fumaric acid, glutaconic acid, traumatic acid, muconic acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, isocitric acid, aconitic acid, mellitic acid and their mixtures and products derived from polycarboxylic acid (all claimed) including energy, fuels, and food.    ADVANTAGE - The method produces products from renewable sources (e.g. biomass) which can be reutilized or simply and safely returned to environment, is cost-effective and high-throughput, and emits minimal greenhouse gas.    DETAILED DESCRIPTION - Method for producing product involves (a) treating reduced recalcitrance lignocellulosic or cellulosic material with one or more enzymes and/or organisms to produce polycarboxylic acid, and converting the polycarboxylic acid to the product, (b) contacting mixed sugar solution comprising nitrogen source and inorganic salts with succinic acid producing organism to produce succinic acid, purifying the succinic acid, and converting the purified succinic acid to the product, where the sugar solution is prepared by saccharifying an electron beam treated cellulosic or lignocellulosic biomass, (c) contacting mixed sugar solution comprising nitrogen source and inorganic salts with an organism chosen from Actinobacillus succinogenes, Anaerobiospirillum succiniciproducens, Mannheimia succiniciproducens, and phosphoenolpyruvate (PEP) carboxylase over-expressing Escherichia coli, fermenting at least one sugar to succinic acid, and converting the succinic acid to the product, where the sugar solution is prepared by saccharifying electron beam treated cellulosic or lignocellulosic biomass, or (d) treating reduced recalcitrance lignocellulosic or cellulosic material with one or more enzymes and/or organisms to produce polycarboxylic acid.