NOVELTY - Reducing (M1) an inhibitor of microbial growth and/or microbial bioproduct production in a hydrolysate of cellulosic biomass, comprises: contacting the hydrolysate with calcium hydroxide and potassium hydroxide, where at least a portion of the inhibitor forms a precipitate in the presence of the calcium hydroxide and potassium hydroxide; and separating the precipitate from the hydrolysate to form a conditioned hydrolysate.    USE - The method is useful for reducing or inactivating an inhibitor of microbial growth and/or microbial bioproduct production in a hydrolysate of cellulosic biomass to form a conditioned hydrolysate, where the conditioned hydrolysate is used to produce a bioproduct which is a solvent comprising butanol (preferred), ethanol, acetone and/or isopropyl alcohol or a biochemical or biochemical intermediate comprising formate, acetate, butyrate, propionate, succinate, methanol, propanol and/or hexanol, and the inhibitor is an organic acid, aldehyde, lignin, lignin derivative, inorganic salt, fatty acid, fatty alcohol, fat, wax, polyester, terpenoid, alkane, wood extractive, Hibbert's ketone, a phenolic or phenylpropanoid compound (all claimed).    ADVANTAGE - The method: provides conditioned hydrolysate comprising sugar molecules, where less than 5% of the sugar molecules are degraded; provides the bioproduct at a greater amount, greater yield, and/or at a greater rate in comparison to an identical hydrolysate that has not been conditioned (all claimed), thus reducing capital cost and risk associated with human and process error, and reducing the number of inoculation events; and separates the precipitated inhibitors easily from the liquid composition.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a conditioned hydrolysate produced by the method;    (2) producing a bioproduct, comprising culturing a microorganism that produces the bioproduct in a medium comprising a conditioned hydrolysate, where the growth of the microorganism is greater in the conditioned hydrolysate in comparison to an identical hydrolysate that has not been conditioned; and    (3) inactivating (M2) an inhibitor of microbial growth and/or microbial bioproduct production in a hydrolysate of cellulosic biomass, comprising contacting the hydrolysate with calcium hydroxide and potassium hydroxide, where at least a portion of the inhibitor is inactivated in the presence of the calcium hydroxide and potassium hydroxide to form the conditioned hydrolysate.