Single-cell protein production in alkali mesquite wood hydrolysates



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Texas Tech University


Studies were undertaken to optimize an alkali treatment of mesquite wood for production of single-cell protein or other products on the hydrolysate. Sodium hydroxide solutions of 0.0, 0.125 N, 0.250 N, 1.25 N, and 2.5 N ware used to treat mesquite wood at 35° C for 1 h. Growth of a ninemember cellulolytic bacterial culture on the alkali hydrolysate prepared as above indicated that the alkali hydrolysate from mesquite wood treated with 2.5 N NaOH was the most suitable for bacterial growth. In subsequent experiments, mesquite wood was treated with 2.5 N NaOH for 1 h at different temperatures. Increased treatment temperature resulted in increased hydrolysis of mesquite wood and degradation of alkali soluble components of the wood. Increased length of treatment resulted in increased wood hydrolysis. A 12-hour treatment at 30° C produced optimum growth based on the amount of wood hydrolysad. Increasing the alkali to wood ratio increased the total carbohydrate yield, reducing sugar yield and growth of the culture. Approximately 3.24 g of cell protein were produced in the alkali hydrolysate per 100 g of wood treated with 2.5 N NaOH at 30° C for 12 hours. An alkali soluble inhibitory substance(s) was/were produced during treatment at high temperature which was removed partially from the alkali hydrolysate by an ion exchange resin. This and previous studias provide a data base for optimization of alkali treatments of woody substrates which are to be used for growth of cellulolytic cultures.