Catalytic properties of cellulases and hemicellulases produced by Lichtheimia ramosa: Potential for sugarcane bagasse saccharification

Abstract

A B S T R A C TThe use of microbial enzyme cocktails for the conversion of polysaccharides of plant origin into fermentable sugars is a global trend. The objectives of this study were to optimize the production of cellulases and hemicellulases by the fungus Lichtheimia ramosa, evaluate the catalytic properties of the produced enzymes, and apply these biocatalysts in the saccharification of sugarcane bagasse. The production of carboxymethylcellulase (CMCase), β-glucosidase, xylanase, and β-xylosidase by L. ramosa were 168.1 ± 2.2, 270.4 ± 8.9, 34 ± 0.8, and 199.2 ± 2.6 U/g of dry substrate, respectively. The optimum pH for the activity of the enzymes ranged between 4.5 and 5.5, and the optimum temperature varied between 55°C and 65°C. The enzymes were stable within a wide range of pH, and approximately 95% of their original activity was preserved when incubated for 1 h at 55°C. The half-lives (t 1/2 ) of CMCase, β-glucosidase, xylanase, and β-xylosidase were 68, 59, 52, and 54 min, respectively, when incubated at 60°C. The enzymes were stable in solutions containing ethanol (10%), and the kinetic parameters (K m and V max ) demonstrated that β-glucosidase from L. ramosa was competitively inhibited by glucose. The enzyme extract produced by L. ramosa was used for the saccharification of sugarcane bagasse pretreated with glycerol and the highest yield of glucose (10.66%) was obtained at 24 h of hydrolysis. The characteristics of the enzymes, combined with the efficiency in hydrolyzing sugarcane bagasse, allow for the application of this enzyme extract to processes of cellulose saccharification for the production of second-generation ethanol.

Cocktail of carbohydrases from Aspergillus niger: an economical and eco-friendly option for biofilm clearance from biopolymer surfaces

“…Earlier also cellulases and hemicellulases from various fungi have been reported to have a temperature optima between 50 and 65 °C e.g. mannanase from Trichoderma reesei and Rhizopus oryzae (Kupski et al 2014 ), Lichtheimia ramose (Garcia et al 2018 ), Aspergillus niger P-19 (Kaur et al 2020b ). Majority of cellulases and xylanases from thermophiles have been reported to have temperature optima between 50 and 80 °C (Bala and Singh 2019 ).…”

“…Sinitsyn et al ( 2014 ) reported optimal cellulose and hemicellulase activities from Penicillium verruculosum in the pH range of 3.5 to 5.5. Cellulases and hemicellulases produced by Lichtheimia ramosa and A. niger P-19 were found to be optimally active in the pH range of 4.5–5.5 (Garcia et al 2018 ) and pH 4.0 (Kaur et al 2020b ) respectively. In our study, all the enzymes in the cocktail were found to be active over a wide pH range, which is a favourable finding as the cocktail can be utilized for biofilm dispersal under diverse conditions.…”

β-Galactosidase-Producing Isolates in Mucoromycota: Screening, Enzyme Production, and Applications for Functional Oligosaccharide Synthesis

“…The power of β-galactosidases to catalyze enzymatic synthesis reactions was examined through the formation of oligosaccharides on different substrates used as glycosyl donors and/or acceptors in mixture. Considering that L. ramosa and R. pusillus exhibited a high β-galactosidase yield and activity during the SSF and the fact that these fungi are important producers of industrial biocatalysts [ 13 , 44 , 45 , 46 ], their enzymes were selected for these experiments. The β-galactosidases obtained in SSF were partially purified, and the crude enzymes were introduced to lactose, skim milk, lactose–fructose, or o NPG–sucrose containing reaction solutions.…”

Optimization of enzymatic hydrolysis for bioethanol production by semi-simultaneous saccharification and fermentation using mature coconut fibre

“…Furthermore, the individual analysis of the experiments showed crude enzyme extract from L. ramosa enabled lower conversions of reducing sugars and glucose (see Table 1, experiments 1 and 5) derived from hydrolysis of cellulose and hemicellulose. This low concentration of β-glucosidase suggests an accumulation of cellobiose, inhibiting endoglucanase and cellobiohydrolase, consequently produces inhibition and repression of the final product during hydrolysis (Singhand Bishnoi, 2012;Gupta and Lee, 2013;Singhania et al, 2013;Zimbardi et al, 2013;Garcia et al, 2018). That way, the ratio of β-glucosidase is low, like in the commercial enzyme preparations of T. reesei (Wang et al, 2013), promoting lower yield of delignified mature coconut fibre into fermentable sugars.…”

“…Due to this breakthrough, the production chain of coconut does not have the correct destination of their agro-industrial and urban waste. Furthermore, wheat bran used in this work is also a good carbon source for lignocellulolytic enzymes production by different microorganisms using in the solid state bioprocessing (SSB), even in the absence of any supplementary carbon or nitrogen sources (Leite et al, 2007;Gonçalves et al, 2013a;Zimbardi et al, 2013;Garcia et al, 2018).…”