Optimization of bioprocess hydrolysis of corn cobs using fungi Trichoderma reesei QM9414/Δxyr1

Plijesan Trichoderma reesei QM9414/Δxyr1 pri optimalnim uvjetima izlučuje ekstracelularne enzime celulaze koje svojim sinergijskim djelovanjem hidroliziraju polisaharid celulozu do monosaharida glukoze. Proces proizvodnje enzima je proveden na rotacijskoj tresilici (150 okr/min) pri temperaturi 30 °C i pH 5,0. Kao izvor ugljika korišteno je pet vrsta sirovina: čista celuloza (100%), kukuruzni oklasci , kombinacija celuloze/ kukuruzni oklasci, lužinom predobrađeni kukuruzni oklasci i pulpa šećerne repe, te su mjerene promjene aktivnosti celulaza. Korištenjem lignoceluloznih sirovina povećana je aktivnost celulaza u ekstracelularnim ekstraktima plijesni Trichoderma reesei QM9414/Δxyr1 u odnosu na čistu celulozu. U drugom dijelu eksperimenta upotrijebljeni su proizvedeni ekstracelularni enzimi za hidrolizu kukuruznih oklasaka. Kod hidrolize promatran je utjecaj procesnih varijabli (pH, temperature i mase enzima) na uspješnost hidrolize i prinos šećera. Za optimiranje bioprocesa korištena je metoda odzivne površine (RSM). Rezultati istraživanja su pokazali da su kritični parametri za hidrolizu kukuruznih oklasaka pH 6,58, temp.26,84 OC, T. reesei 1,5 mg protein/g s.tv, Celluclast 1,2 mg protein/g s.tv. Na prinos šećera nakon hidrolize kukuruznih oklasaka najveći utjecaj imao je pH, dok je utjecaj masa proteina multienzimskih kompleksa T. reesei i Celluclasta (mg protein/g s.tv.) na prinos šećera pozitivan, što se iskazuje povećanjem prinosa šećera tijekom hidrolize u podlogama s većim udjelom proteina multienzimskih kompleksa T. reesei i Celluclasta.The fungi Trichoderma reesei QM9414/Δxyr1 produces extracellular enzymes (crude extracts) under optimal conditions which, with their synergic action, hydrolize polysaccharide cellulose into monosaccharide glucose. The enzyme production was done on a rotary shaker (150 rpm) under 30 °C and with pH 5.0. Five types of raw materials were used as a carbon source: pure cellulose (100%), corn cobs and combination of cellulose/corn cobs, alkaline pretreated corn cobs and sugar beet pulp. Changes in cellulase activity were measured. Compared to pure cellulose, the cellulase activity in Trichoderma reesei QM9414/Δxyr1 crude extracts was higher when using lignocellulosic raw materials. In the second part of the experiment produced crude extracts were used for corn cob hydrolysis. The influence of process variables (pH, temperature, enzyme concentration) on the success of the hydrolysis and sugar income was measured. For the bioprocess optimisation the response surface methodology (RSM) was used. Results of the research showed that the critical parameters for corn cob hydrolysis were pH 6.58, temperature 26.84°C, T. reesei 1.5 mg protein/g dw, Celluclast 1.2 mg protein/g dw. After hydrolysis of corn cobs the biggest influence on yields of sugar had the pH, while the influence of protein mass of the multienzyme T. reesei complex and Celluclast (mg protein/g dw) was positive. This is shown in increased sugar yields in media with larger protein shares of the multienzyme complexes of T. reesei and Celluclast