Effect of cross-linked enzyme aggregates in hierarchically mesocellular mesoporous magnetic silica preparation conditions towards enzyme activity retention

This work aimed to optimize ten preparation factors that might influence the cellulase and xylanase activity retention of cross-linked enzyme aggregates in hierarchically mesocellular mesoporous magnetic silica. The factors were optimized using the fractional factorial design (210-5). The optimized output was occurred at 2 mL of enzyme amount, magnet-to-enzyme ratio of 1:0.15, enzyme adsorption at 26°C and 162 rpm in 40 min, enzyme-to-precipitant ratio of 1:11, 0.05% (v/v) of glutaraldehyde concentration, and cross-linking process at 37°C and 300 rpm in 2 h. The factors were examined to observe the effect of every factor towards cellulase and xylanase acrivity retention

Assessment of sewage sludge bioremediation at different hydraulic retention times using mixed fungal inoculation by liquid-state bioconversion

Sustainable, environmental friendly, and safe disposal of sewage treatment plant (STP) sludge is a global expectation. Bioremediation performance was examined at different hydraulic retention times (HRT) in 3–10 days and organic loading rates (OLR) at 0.66–7.81 g chemical oxygen demand (COD) per liter per day, with mixed filamentous fungal (Aspergillus niger and Penicillium corylophilum) inoculation by liquid-state bioconversion (LSB) technique as a continuous process in large-scale bioreactor. Encouraging results were monitored in treated sludge by LSB continuous process. The highest removal of total suspended solid (TSS), turbidity, and COD were achieved at 98, 99, and 93 %, respectively, at 10 days HRT compared to control. The minimum volatile suspended solid/suspended solid implies the quality of water, which was recorded 0.59 at 10 days and 0.72 at 3 days of HRT. In treated supernatant with 88 % protein removal at 10 days of HRT indicates a higher magnitude of purification of treated sludge. The specific resistance to filtration (SRF) quantifies the performance of dewaterability; it was recorded minimum 0.049 × 1012 m kg−1 at 10 days of HRT, which was equivalent to 97 % decrease of SRF. The lower OLR and higher HRT directly influenced the bioremediation and dewaterability of STP sludge in LSB process. The obtained findings imply encouraging message in continuing treatment of STP sludge, i.e., bioremediation of wastewater for environmental friendly disposal in near future

The effect of particle size of empty fruit bunch and ratio of biosludge of pulp and paper on biochemical changes in composting process

The abundance of empty fruit bunches (EFB) is a result of many palm oil industries increasing their crude palm oil production. Composting is a good, environmentally friendly alternative to overcome EFB. Two different ratios of EFB with biosludge of pulp and paper of 1 : 1 and 3 : 2, respectively, were used in this composting. The particle size of EFB was set into three different sizes of 0.5; 1.5 and 2.5 cm. The best treatment that was obtained from this study was SR4 where the EFB particle size was 1.5 cm, and the ratio between EFB and biosludge of pulp and paper was 3 : 2, respectively. The nitrogen value of SR4 increased from 1.41% to 2.71%, and C/N ratio decreased from 36.74 to 12.17 in 90 days. The population peak of bacteria of SR4 in the thermopilic phase achieved about 33.67 x 1010 cfu/g. These two treatment combinations had shown an increase in EFB composting efficiency

Screening of factors influencing exo-polygalacturonase production by Aspergillus niger ATCC 120120 using two-level fractional factorial design

Exo-polygalacturonase was produced by Aspergillus niger ATCC 120120 in a solid-state fermentation using Nephrolepis biserrata leaves. Factors affecting the production of exo-polygalacturonase were determined using a two-level fractional factorial design. The screening process for six factors; pH, incubation time, temperature, pectin concentration, inoculum size and moisture content, that influence the production of exo-polygalacturonase by A. niger was performed. The result of variance analysis (ANOVA) suggested that there were four statistically significant (P < 0.005) factors in the production of exo-polygalacturonase by A. niger. These factors were incubation time, temperature, pectin concentration and moisture content. The statistical analysis shows that the linear mathematical model is significant with coefficient of determination (R2) value of 0.9711. The optimum production of exo-polygalacturonase obtained using the model in this study was at 40.00 U/g

Optimization of process parameters for pilot-scale liquid-state bioconversion of sewage sludge by mixed fungal inoculation

Liquid-state bioconversion (LSB) technique has great potential for application in bioremediation of sewage sludge. The purpose of this study is to determine the optimum level of LSB process of sewage sludge treatment by mixed fungal (Aspergillus niger and Penicillium corylophilum) inoculation in a pilot-scale bioreactor. The optimization of process factors was investigated using response surface methodology based on Box–Behnken design considering hydraulic retention time (HRT) and substrate influent concentration (S0) on nine responses for optimizing and fitted to the regression model. The optimum region was successfully depicted by optimized conditions, which was identified as the best fit for convenient multiple responses. The results from process verification were in close agreement with those obtained through predictions. Considering five runs of different conditions of HRT (low, medium and high 3.62, 6.13 and 8.27 days, respectively) with the range of S0 value (the highest 12.56 and the lowest 7.85 g L−1), it was monitored as the lower HRT was considered as the best option because it required minimum days of treatment than the others with influent concentration around 10 g L−1. Therefore, optimum process factors of 3.62 days for HRT and 10.12 g L−1 for S0 were identified as the best fit for LSB process and its performance was deviated by less than 5% in most of the cases compared to the predicted values. The recorded optimized results address a dynamic development in commercial-scale biological treatment of wastewater for safe and environment-friendly disposal in near future

Biochemical and physical characterization of immobilized Candida rugosa lipase on metal oxide hybrid support

Enzyme immobilization on inorganic materials is gaining more attention with the potential characteristics of high-surface-area-to-volume ratios, increasing the efficiency of enzyme loading on the support. Metal oxide hybrid support was prepared by a wetness impregnation of five metal precursors, including CaO, CuO, MgO, NiO, and ZnO, on Al2O3 and used as a support for the immobilization of Candida rugosa lipase (CRL) by adsorption. Maximum activity recovery (70.6%) and immobilization efficiency (63.2%) were obtained after optimization of five parameters using response surface methodology (RSM) by Box–Behnken design (BBD). The biochemical properties of immobilized CRL showed high thermostability up to 70 °C and a wide range in pH stability (pH 4–10). TGA-DTA and FTIR analysis were conducted, verifying thermo-decomposition of lipase and the presence of an amide bond. FESEM-EDX showed the homogeneous distribution and high dispersion of magnesium and CRL on MgO-Al2O3, while a nitrogen adsorption–desorption study confirmed MgO-Al2O3 as a mesoporous material. CRL/MgO-Al2O3 can be reused for up to 12 cycles and it demonstrated high tolerance in solvents (ethanol, isopropanol, methanol, and tert-butanol) compared to free CRL

Biomass degradation : Challenges and strategies in extraction and fractionation of hemicellulose

Extraction and fractionation of hemicellulose from complex lignocellulosic biomass are crucial steps to acquiring purified hemicellulose that can probably used in biofuel and biochemical sectors. Yet, several challenges have impeded for obtaining the hemicellulose fraction as it involves the complexity of extracting and fractioning hemicellulose. In this study, the authors have discussed the outline of the most prospective and effective method for separation, extraction, and purification of hemicellulose-rich biomass. A current overview of challenges and problems in hemicellulose separation was addressed. Subsequently, the influence of heterogeneous biomass types, cultivation and harvesting times, accessible surface areas, acetyl and other functional groups on purity was observed. On the other hand, several proper strategies efficiently employed in hemicellulose extraction and fractionation are provided. The biochemical process gives a highly positive contribution to sustaining hemicellulose-based bioproducts. Biological pre-treatment of lignocellulose using enzymes and bacteria is convinced as the most effective and efficient method to reduce the lignin content and to improve the purity due to less inhibitory and minimal coke formation. Saccharomyces cerevisiae has been widely used in the hemicellulose-based bioprocess due to resulting in high conversion (>80%) and yield (>70%). The hydrothermal method followed by multistep ultrafiltration treatment generated the highest hemicellulose purity (100%) and by-product removal (94.4–99.2 wt%). Comprehensive strategies for hemicellulose extraction and fractionation involving biological and non-biological treatments are also the highlights of this article

Production of cyclodextrin glucanotransferase from alkalophilic Bacillus sp. TS1-1: Optimization of carbon and nitrogen concentration in the feed medium using central composite design

Optimisation of nutrient feeding was developed to overcome the limitation in batch fermentation and to increase the CGTase production from Bacillus sp. TS1-1 in fed batch fermentation. Optimisation of the C/N ratio in the feed stream was conducted in a 5 l fermenter, where feeding was initiated at constant rate of 0.02 h−1. In our initial screening process, the addition of nitrogen source boosted the growth of the microbes, but on the other hand reduced the CGTase production. The amount of tapioca starch and yeast extract was optimised in order to obtain a sufficient growth and thus, increased the CGTase production. Results were analysed using three-dimensional response surface plot, and the optimised values of carbon and nitrogen concentration of 3.30% (w/v) and 0.13% (w/v) were obtained, respectively. CGTase activity increased up to 80.12 U/ml, which is 13.94% higher as compared to batch fermentation (70.32 U/ml). This also led to 14.54% increment of CGTase production in fed batch culture as compared to the production before the optimisation. The CGTase activity obtained was close to the predicted value, which is 78.05 U/ml. © 2006 Elsevier B.V. All rights reserved. Keywords: Cyclodextrin glucanotransferase; C/N ratio; Fed batch; Central composite desig

The effect of particle size of empty fruit bunch and ratio of biosludge of pulp and paper on biochemical changes in composting process

The abundance of empty fruit bunches (EFB) is a result of many palm oil industries increasing their crude palm oil production. Composting is a good, environmentally friendly alternative to overcome EFB. Two different ratios of EFB with biosludge of pulp and paper of 1 : 1 and 3 : 2, respectively, were used in this composting. The particle size of EFB was set into three different sizes of 0.5; 1.5 and 2.5 cm. The best treatment that was obtained from this study was SR4 where the EFB particle size was 1.5 cm, and the ratio between EFB and biosludge of pulp and paper was 3 : 2, respectively. The nitrogen value of SR4 increased from 1.41% to 2.71%, and C/N ratio decreased from 36.74 to 12.17 in 90 days. The population peak of bacteria of SR4 in the thermopilic phase achieved about 33.67 x 1010 cfu/g. These two treatment combinations had shown an increase in EFB composting efficiency

Production of cyclodextrin glucanotransferase (CGTase) from Bacillus sp. TS1-1: process optimisation

The effect of pH and temperature were investigated for an optimized condition of cyclodextrin glucanotransferase (CGTase) production from Bacillus sp. TS1-1. The optimization process was analysed using Central Composite Experimental Design in Response Surface Methodology (RSM) by Design Expert Version 6.0.4 (StatEase, USA). This design was employed to derive a statistical model for the effects of pH and temperature on the production of CGTase from Bacillus sp. TS1-1. The coefficient of determination, R2 was found to be 97.85%. The temperature of 29.59C and the pH of 10.32 had been found to be the optimum conditions for the maximum production of CGTase after 24 hr of incubation. In these conditions, the CGTase activity was attained to be 75.48 U/ml, which was close to the model predictions