Dachyar Arbain

Potential halophilic cellulases for in situ enzymatic saccharification of ionic liquids pretreated lignocelluloses

Ionic liquids (ILs) have been used as an alternative green solvent for lignocelluloses pretreatment. However, being a salt, ILs exhibit an inhibitory effect on cellulases activity, thus making the subsequent saccharification inefficient. The aim of the present study is to produce salt-tolerant cellulases, with the rationale that the enzyme also tolerant to the presence of ILs. The enzyme was produced from a locally isolated halophilic strain and was characterized and assessed for its tolerance to different types of ionic liquids. The results showed that halophilic cellulases produced from Aspergillus terreus UniMAP AA-6 exhibited higher tolerance to ILs and enhanced thermo stability in the presence of high saline conditions.

Applicability evaluation of Deep Eutectic Solvents–Cellulase system for lignocellulose hydrolysis

Deep Eutectic Solvents (DESs) have recently emerged as a new generation of ionic liquids for lignocellulose pretreatment. However, DESs contain salt components which tend to inactivate cellulase in the subsequent saccharification process. To alleviate this problem, it is necessary to evaluate the applicability of the DESs-Cellulase system. This was accomplished in the present study by first studying the stability of cellulase in the presence of selected DESs followed by applicability evaluation based on glucose production, energy consumption and kinetic performance. Results showed that the cellulase was able to retain more than 90% of its original activity in the presence of 10% (v/v) for glycerol based DES (GLY) and ethylene glycol based DES (EG). Furthermore, both DESs system exhibited higher glucose percentage enhancement and lower energy consumption as compared to diluted alkali system. Among the two DESs studied, EG showed comparatively better kinetic performance.

Improvement of halophilic cellulase production from locally isolated fungal strain

Halophilic cellulases from the newly isolated fungus, Aspergillus terreus UniMAP AA-6 were found to be useful for in situ saccharification of ionic liquids treated lignocelluloses. Efforts have been taken to improve the enzyme production through statistical optimization approach namely Plackett–Burman design and the Face Centered Central Composite Design (FCCCD). Plackett–Burman experimental design was used to screen the medium components and process conditions. It was found that carboxymethylcellulose (CMC), FeSO4·7H2O, NaCl, MgSO4·7H2O, peptone, agitation speed and inoculum size significantly influence the production of halophilic cellulase. On the other hand, KH2PO4, KOH, yeast extract and temperature had a negative effect on enzyme production. Further optimization through FCCCD revealed that the optimization approach improved halophilic cellulase production from 0.029 U/ml to 0.0625 U/ml, which was approximately 2.2-times greater than before optimization.

Synergistic action of deep eutectic solvents and cellulases for lignocellulosic biomass hydrolysis

Abstract The increased awareness of environmental and economic issues has led many researchers to seek green and low-cost solvent for the conversion of lingocellulosic biomass to bioenergy. In this context, deep eutectic solvents, a new class of ionic liquids, have been regarded as greener substitute to conventional solvents for pretreatment of biomass. This paper is concerned with the stability and synergicity action of deep eutectic solvents for the digestion of biomass. The stability was studied by incubating commercial cellulases to different concentration of ethylene glycol–choline chloride-based deep eutectic solvent. The synergistic tests were studied by performing enzymatic saccharification after pretreatment of rice husk with deep eutectic solvent at various temperatures. The stability test showed that, the commercial cellulase activity retained more than 90% of relative activity after 1 hour of incubation in 10(%,v/v) deep eutectic solvent at 30°C. The prepared deep eutectic solvent in combination with commercial cellulases study showed that the higher pretreatment temperature improved the production of simple sugar from rice husk.

Ionic Liquids: Green Solvent for Pretreatment of Lingnocellulosic Biomass

Green technology has become the primary concern of nations around the world. In-line with this concern, lignocellulosic biomass is often advocated as significant starting material for a greener production. However, the current biomass conversion cannot be considered as green due to the use of acid or alkaline during its pretreatment. An introduction of ionic liquids (ILs) as replacement of acids or alkaline for the pretreatment of lingo-cellulosic materials is gaining interest due to their minimal waste, nonvolatility and low toxicity and therefore considered green. This paper discusses the benefits of ILs as a green solvent for pretreatment of lignocellulosic biomass.

Fourier transform infrared spectroscopy (FTIR) analysis of paddy straw pulp treated using deep eutectic solvent

This study focus on Fourier Transform Infrared Spectroscopy (FTIR) analysis of paddy straw pulp treated using deep eutectic solvent (DES). DES was synthesized using potassium carbonate and glycerol at different molar ratio under normal atmospheric pressure. Pretreatment of lignocellulosic biomass was carried out at temperature of 120°C for 60 minutes under mass ratio of paddy straw to DES 1:9. The chemical structures of the untreated paddy straw and paddy straw pulp treated with different molar ratio of DES were analyzed using FTIR. The characterization result from FT-IR spectra indicated that the potassium carbonate-glycerol DES deconstructed the structures of paddy straw by removing lignin and hemicellulose during the pulping process. The peak intensity that occurs at region between 900 cm−1 and 1500 cm−1 shows that the presence of elevated level of cellulose after lignocellulosic pulping. From FT-IR analysis, DES could not remove the functional group of lignin and hemicellulose completely but yet expos...

Effect of structural changes of lignocelluloses material upon pre-treatment using green solvents

The Malaysia Biomass strategy 2020 stated that the key step of biofuel production from biomass lies on the pretreatment process. Conventional ‘pre-treatment’ methods are ‘non-green” and costly. The recent green and cost-effective biomass pretreatment is using new generation of Ionic Liquids also known as Deep Eutectic Solvents (DESs). DESs are made of renewable components are cheaper, greener and the process synthesis are easier. Thus, the present paper concerns with the preparation of various combination of DES and to study the effect of DESs pretreatment process on microcrystalline cellulose (MCC), a model substrate. The crystalline structural changes were studied using using X-ray Diffraction Methods, Fourier Transformed Infrared Spectroscopy (FTIR) and surface area and pore size analysis. Results showed reduction of crystalline structure of MCC treated with the DESs and increment of surface area and pore size of MCC after pre-treatment process. These results indicated the DES has successfully converte...

Galactose consuming microbes for ethanol production from seaweed

Gracilaria sp. is one of macroalgae that contain high amount of sugar especially galactose. This galactose can be fermented into bioethanol by galactose-consuming microbes similar to the widely known ethanol production by yeast S.cerevisae. Hence the main objective of this study is to isolate galactose consuming microbes which capable of fermenting galactose into bioethanol. For this purpose, microbes-containing sample from seaweed culture were grown on galactose agar and tested for their survival as well as ethanol production capability. Seven isolated microbes belong to fungi and bacteria species were tested for their capability in fermenting galactose to produce ethanol. The concentrations of ethanol that have been produced by isolated microbes were analyzed by dichromate method whereas the consumption of galactose was determined by Dinitrosalicyclic acid (DNS) method. It was found that ethanol production resulted from fermentation by S1, S2, S3 and S4 were 0.80% (w/v), 0.74% (w/v), 0.81% (w/v) and 0.85% (w/v) respectively. Identification of these strains, as well as optimization of their ethanol fermentation are undergoing in our laboratory.

Growth Kinetic Study on Lyophilized and Cryopreserved Pleurotus sajor-caju Spawn

A study was conducted to determine the most optimal preservation technique for P. sajor-caju spawns which produce maximum specific growth rate and shortest doubling time by using contois kinetic model. The analyzed experimental data showed that lyophilized P. sajor-caju spawn showed the highest maximum specific growth rate, and shortest doubling time compared to cryopreserved P. sajor-caju spawn and 4oC stored P. spawn. There was no significant difference in aspect of growth rate between the lyophilization and cryopreservation techniques which were; 0.148 (μmax)/ (g/day) and 0.147(μmax)/ (g/day) respectively. Based on the result, lyophilization technique was considered as the best preservation technique for preserving P. sajor-caju spawn due to high maximum growth rate which indicates high survival after exposure to preservation treatment.

Preparation and characterisation of rice husk activated carbon for neutral protease adsorption

Abstract The worldwide annual production of rice husk is estimated about 500 million tonnes, and usually it was burned as one way of disposal. Despite of its high silica content, rice husk is well known as a good adsorbent for several types of compound, including protein. In order to improve its adsorption capacity, it is necessary to convert properly rice husk into activated carbon. The present paper deals with the preparation and characterisation of rice husk activated carbon followed by its utilisation for enzyme adsorption. Rice husk is initially pre-carbonised at 400°C for 4 hours before activating with NaOH at 750°C for 2 hours in the presence of nitrogen. The prepared activated carbon was further characterised with Brunauer–Emmert–Teller and scanning electron microscopy, to observe the morphology changes after treatment. It was found that the surface area has increased from 8·4228 m2 g−1 (rice husk) to become 1646·6264 m2 g−1 (rice husk activated carbon). Additionally, small pores were well developed during the process, which can be observed by scanning electron microscopy. The rice husk activated carbon was used for neutral protease adsorption. It was found that rice husk activated carbon and commercial activated carbon adsorps the enzyme more efficiently compared to rice husk. Moreover, the efficiency of prepared rice husk activated carbon is comparable with commercial activated carbon.