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Editor’s Choice : Continuous Ethanol Fermentation in Immersed, Cross-Flow Microfiltration Membrane Bioreactor with Cell Retention
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Abstract: The key objective of this study was to devise a continuous ZeeWeed® membrane-based, immersed, microfiltration (MF) laboratory scale fermentation system for ethanol production with cell retention to achieve effective ethanol productivity, flux rates and sugar utilization. The new bioreactor was compared to the fermentation kinetics’ of the ultrafiltration unit.A synthetic glucose based medium was fermented by fresh, baker’s yeast to produce ethanol. The cells were not recycled; the medium was continuously withdrawn by filtration through an internal, immersed hollow-fiber cartridge. In this way, the inside of the membrane was exposed to the ethanolic solution, while broth with viable yeast cells remained outside the membrane. This design, with a cell retention system, provided much less membrane fouling (loss of about 76% of the original water flux after 96 hours of filtration) than while using the ultrafiltration (UF) external hollow-fiber membrane with cell recycling (loss of 97% of the original water flux after 2-3 hours of operation). Both modules converted at least 95% of glucose with biomass concentration of 30 g/L, and the final ethanol concentration of 62 g/L. However, the UF membrane became plugged after only 2 hrs of operation. The ZeeWeed® membrane operated successfully for 96 hrs with a final flux of 4 L/h m2 with ethanol concentration of 62.4 g/l, biomass yield 0.34 g/g and cell viability of 95.3%. This concept could be successfully used for biofuel production. A very strong positive correlation was observed between the biomass and EtOH concentration (R=0.98; at p<0.05). Keywords: Continuous ethanol fermentation, hollow fiber, cross-flow microfiltration, membrane bioreactor, cell retention, Saccharomyces cerevisiae. Download Full Article |
Editor’s Choice : Effect of Biofertilizer Addition on Nitrous Oxide Emission
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Abstract: Application of nitrogen fixing biofertilizer, such as Azotobacter, has a potential for reducing nitrous oxide (N2O) emission. The aim of this study was to examine the effect of nitrogen fixing biofertilizer addition to common practices of urea and fresh cattle manure usages for maize (Zea mays L.) growing on N2O emission. The field experiment was conducted at GunungKidul, Yogyakarta, Indonesia. The treatments were addition of fresh cattle manure (M), fresh cattle manure added with nitrogen fixing biofertilizer (MB), urea (U), urea added with nitrogen fixing biofertilizer (UB), and control (no N fertilizer added). Nitrogen contents of the added urea and fresh cattle manure were adjusted to be equal. Urea and fresh cattle manure were given three times throughout the experiment period, i.e. 12, 30, and 48 days after planting (DAP). Urea was given at a rate of 44, 29, and 15 kg.ha-1, respectively while fresh cattle manure was given at a rate of 6000, 4000, and 2000 kg.ha-1, respectively. The emitted N2O was collected using a closed-chamber method at 24, 42, 60, and 72 DAP and were determined using Gas Chromatograph. Soil properties including available N (NH4+-N and NO3--N) and organic C contents were also analyzed. On the harvesting time, the harvest index and the grain yield were determined. Biofertilizer addition influence decomposition process of cattle manure and urea that led to mineralization and nitrification of residual organic matterand hence to cause soil NH4+N in the order concentration of M treatment > MB > U > UB>C, and soil NO3--N of MB treatment > M > U > UB>C. Reduction of NO3-N was resulted in the highest N2O emission of M >U>MB>UB>C(P < 0.01). The grain yield, and harvest index of maize wereresulted in the order value of MB> UB > U > M>C treatments.Available mineral N and soil organic C contents strongly affected N2O emission (P < 0.01).The results suggested that biofertilizer addition to common agricultural practices reduce N2O emission and simultaneusly increased grain yield, and harvest index of maize. Keywords: Azotobacter, urea, cattle manure, nitrous oxide.Download Full Article |
Editor’s Choice : Optimization of Ornithogalum Saundersiae Baker Propagation by Twin Scale Cuttings with the Use of Biopolymers
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Abstract: Ornithogalum saundersiae Baker, commonly known as Giant Chincherinchee, is an interesting bulbous plant with horticultural and medicinal potential. For increasing production of O. saundersiae planting material can be used rapid propagation by twin scaling. The aim of the study was to investigate the effect of parent bulb circumference, twin scale cutting weight and the type of biopolymer coating on the yield ofO. saundersiae bulblets. Propagules were encapsulated in three polymer mixtures: 1% gellan and 0.5% chitosan; 1% iota-carrageenan and 0.5% chitosan; 1% xanthan and 0.5% chitosan. Chitosan had a molecular weight (Mw) of 48 000 g·mol-1 and degree of deacetylation (DD) 85%. The twin scale cuttings were mixed with perlite and peat 1:1 (v/v) and stored for 100 days at 22-24˚C and relative humidity of 70-80%. The highest number of bulblets was produced by the parent bulbs 22-24 cm in circumference. The bulblets derived from the twin scale cuttings weighing 2.1-4.1 g were characterized by greater fresh weight, the greatest circumference and they produced the highest number of adventitious roots. Encapsulation of twin scale cuttings in gellan and chitosan or in iota-carrageenan and chitosan, resulted in the bulblets with more roots and greater weight and circumference, as compared to the control ones and the bulblets obtained from scales treated with xanthan and chitosan. Keywords: Bulblets,carrageenan, chitosan, Giant Chincherinchee, gellan. Download Full Article |
Editor’s Choice : Production and Partial Purification of Amylase By Aspergillus niger Isolated from Cassava Peel
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Abstract: Aspergillus niger strains 1, 2 and 3 isolated from cassava dumpsites were used for the production of amylase enzyme. The Aspergillus niger strains 1, 2 and 3 had diameter (mm) zone of clearance of 17.0, 23.0 and 8.0 respectively using Potato dextrose agar plates fortified with starch. Studies on the amylase enzyme activity (mg/ml) of Aspergillus niger strains 1 and 2 showed 19,340 and 16,510 respectively. These values were higher than the commercially available amylase enzyme that had an activity of 5,722.2. The protein (mg/ml) and specific activity (units/mg) for amylase from Aspergillus niger strain 1 was 28.39 and 681.23 while 21.76 and 758.73 from Aspergillus niger 2 respectively. Purification using ammonium sulphate (% w/v) at 60, 80 and 100 on amylase enzyme from Aspergillus niger strain 1 for enzyme activity, protein and specific activity was 44405.49, 17.01 and 2610.55, 28949.76, 23.62 and 1225.65, 36220.25, 16.67, and 2172.787 respectively. The microbial production of Amylase enzyme in Nigeria from Cassava peel will reduce cost of production, convert cassava peel from waste condition to wealth, and will boost economy through indigenous industrialization. Keywords: Aspergillus niger, Amylase enzyme, Cassava peel, Partial purification.Download Full Article |
