Q2. What is the effect of free sugars on the growth of fungi?
Although free sugars as glucose can repress the microbial enzyme synthesis, in SSF the presence of free sugars on solid substrate favour the growth of fungi (Ertan-Inceoǧlu et al., 2014).
Q3. What was the test used to determine the difference between the two wastes?
A paired-sample comparisononfidence level.t-test was used to compare both wastes and to determine differences at 95% confidence level.
Q4. What is the reason for the undetectable enzymatic activity after SSF?
The undetectable enzymatic activity after SSF with COP is probably caused by the presence of high initial concentration of fats with recognized antimicrobial properties which delayed the beginning of the fermentation and, on the other hand, to the high concentration of lignin, which needs specific enzymes and high temperatures to be degraded.
Q5. What is the common reason for the bubbles to form?
Ultrasound pre-treatment (US) causes cavitation bubbles formation in the liquid phase, the bubbles grow and then violently collapse when they reach a critical size.
Q6. What are the main producers of cellulases and xylanases?
the filamentous fungi Aspergillusuvarum and Aspergillus ibericus have been identified as producers of cellulases and xylanases (Salgado et al., 2014b).
Q7. What is the effect of ultrasounds on lignocellulosic biomass?
The effect of ultrasounds on lignocellulosic biomass has been mainly employed for extracting hemicellulose, cellulose and lignin.
Q8. What are the main criteria to consider when selecting a pre-treatment?
To select the most appropriate pre-treatment, several criteria must be taken into account such as to minimize loss of hemicelluloses and cellulose, do not require the addition of toxic chemicals, minimize the use of energy, low capital equipment and chemicals demand, as well as the possibility of an easier scale-up (Holtzapple and Humphrey, 1984).
Q9. How was the extraction of the enzymes performed?
The extraction of enzymes was performed with a solution composed of 1% NaCl and 0.5% Triton-X100 at room temperature in an L:S ratio of 5 and with agitation for 1 h.
Q10. What is the advantage of the acid pretreatment?
In spite of this pretreatment has the advantage of solubilizing hemicellulose, mainly xylan to fermentable sugars, sugar degradation compounds are detected, and affect the microorganism metabolism in the fermentation step (Alvira et al., 2010).
Q11. What was the maximum activity of cellulases?
When EOP was used, A. niger achieved maximum activity for cellulases (38 U/g of solid substrate) and for xylanases (28 U/g of solid substrate).
Q12. What is the concentration of hemicellulose after acid pretreatment?
After AH, the concentration of sugars was 311 ± 19 mg/g because the acid pretreatment solubilized monomeric sugars from hemicelluloses.
Q13. What are the main industrial sources of cellulases and xylanases?
Several fungi are able to produce this enzyme cocktail; Trichoderma reesei and Aspergillus niger are the main industrial sources of cellulases and xylanases due to their ability to secrete high quantities of hydrolytic enzymes.