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关键词： Brazzein   Natural sweeteners   Recombinant protein production   Agrobacterium-mediated transformation   Transgenic lines   Abscisic acid   Hydrogen peroxide   Air-lift bioreactor   Food industry  

摘要： Plant-based recombinant protein production systems are powerful tools that can be used instead of microbial and animal cell culture systems. The aim of this study was to establish a stable brazzein production system from carrot cell suspension using bioreactor. Using Agrobacterium-mediated transformation (stress-inducible SWPA2 promoter and brazzein gene), three transgenic lines (TC1, 11, 12) were generated. During the TC12 culture period, cell proliferation increased rapidly up to 15 days, and the maximum cell division rate (log phase) was reached after 6 days of culture. Fresh weight peaked at day 18, 3.8-fold (7.6 g 100 mL(-1)) higher than on day 1, and gene expression was tenfold higher on day 27 than on day 0. The brazzein-encoding gene was also analyzed after treatment with various stress factors for increase of brazzein gene expression, and abscisic acid (ABA) and hydrogen peroxide (H2O2) proved most effective. In particular, the gene expression was enhanced 2.5-fold with 220 mu M H2O2 and 2.8-fold with 50 mu M ABA, compared with controls. Transgenic cells were then transferred to various types of air-lift bioreactor, and the column bioreactor achieved a higher biomass (238.9 g L-1) than cone and balloon bioreactors. These results demonstrate an efficient protein production system for brazzein using an air-lift bioreactor that may be suitable for the use in the food industry.

关键词： Bioaerosol   Biofiltration   Emission   Control technology   Inactivation  

摘要： Bioaerosols have widely been a concern due to their potential harm to human health caused by the carrying and spreading of harmful microorganisms. Biofiltration has been generally used as a green and effective technology for processing VOCs. However, bioaerosols can be emitted into the atmosphere as secondary pollutants from the biofiltration process. This review presents an overview of bioaerosol emissions from gas bioreactors. The mechanism of bioaerosols production and the effect of biofiltration on bioaerosol emissions were analyzed. The results showed that the bioaerosol emission concentrations were generally exceeded 10(4) CFU m(-3), which would damage to human health. Biomass, inlet gas velocity, moisture content, temperature, and some other factors have significant influences on bioaerosol emissions. Moreover, as a result of the analysis done herein, different inactivation technologies and microbial immobilization of bioaerosols were proposed and evaluated as a potential solution for reducing bioaerosols emissions. The purpose of this paper is to make more people realize the importance of controlling the emissions of bioaerosols in the biofiltration process and to make the treatment of VOCs by biotechnology more environmentally friendly. Additionally, the present work intends to increase people's awareness in regards to the control of bioaerosols, including microbial fragment present in bioaerosols. (C) 2020 Published by Elsevier Ltd.

关键词： Metal removal   Microbial community analysis   Mining-influenced water treatment   Sulfate-reducing bacteria   Sulfate-reducing bioreactor  

摘要： Sulfate-reducing bioreactors, also called biochemical reactors, represent a promising option for passive treatment of mining-influenced water (MIW) based on similar technology to aerobic/anaerobic-constructed wetlands and vertical-flow wetlands. MIW from each mine site has a variety of site-specific properties related to its treatment;therefore, design factors, including the organic substrates and inorganic materials packed into the bioreactor, must be tested and evaluated before installation of full-scale sulfate-reducing bioreactors. Several full-scale sulfate-reducing bioreactors operating at mine sites provide examples, but holistic understanding of the complex treatment processes occurring inside the bioreactors is lacking. With the recent introduction of high-throughput DNA sequencing technologies, microbial processes within bioreactors may be clarified based on the relationships between operational parameters and key microorganisms identified using high-resolution microbiome data. In this review, the test design procedures and precedents of full-scale bioreactor application for MIW treatment are briefly summarized, and recent knowledge on the sulfate-reducing microbial communities of field-based bioreactors from fine-scale monitoring is *** points center dot Sulfate-reducing bioreactors are promising for treatment of mining-influenced water. center dot Various design factors should be tested for application of full-scale bioreactors. center dot Introduction of several full-scale passive bioreactor systems at mine sites. center dot Desulfosporosinus spp. can be one of the key bacteria within field-based bioreactors.

关键词： Sugarcane syrup   FOS   pH-stat bioreactor   Enzymatic synthesis   Prebiotics   Native sugar  

摘要： Fructooligosaccharides (FOS) have gained significant attention for their prebiotic properties. Given that sugarcane syrup (SS) is sucrose-rich but with other nutritional benefits, its direct transformation into FOS may add value to this product. Therefore, the aims of this study were to develop FOS conversion from SS and to define the kinetic behaviour of FOS synthesized in a 1-L specialized pH-star bioreactor (SPSB). The SS was composed of sucrose (58.93%) with considerable antioxidant capacities and Y-aminobutyric acid. The developed SPSB process consisted of three stages: evaporation of sugarcane juice into syrup (68-75 degrees Brix) (stage 1), optimization of the Viscozyme L and SS mixture at different reaction temperatures (47-55 degrees C) (stage 2), and upscaling of the optimized reaction system under defined conditions in a 1 L-SPSB system (stage 3). In the 1 L-SPSB system, the enzymatic reaction yielded 32.22% of FOS from SS after a 6 h reaction, which is comparable with a pure system containing an equivalent concentration of 10% of sucrose as initial substrate with 39.55% yield. This result demonstrated the efficient conversion of SS into FOS, supporting the utilization of sugarcane juice for its health benefits.

关键词： Anaerobic digestion   Chicken manure   Anaerobic membrane bioreactor   Ammonia stripping   Hyper-thermophilic hydrolysis  

摘要： The slow hydrolysis rate and ammonia inhibition effects significantly limit the performance of anaerobic digestion (AD) of nitrogen rich wastes. An innovative two-stage AD was therefore investigated for chicken manure by combining hyper-thermophilic (70 °C) pretreatment and a anaerobic membrane bioreactor (AnMBR). An in-situ stripping unit was assembled into the AnMBR to remove the ammonium-N, thus alleviating the inhibition effects. Through the 120-day experiment, the hydraulic retention time was optimized at 15 days for AnMBR with a constant retention 4 days for pretreatment. The hydrolysis efficiency and methane yield reached 72.4% and 352 mL-CH₄/g-VS_in respectively. About 3000 mg/L ammonium-N was removed through stripping, attributing to methane yield increased by 139 mL-CH₄/g-VS_in and volatile fatty acids decreased by 2683 mg/L compared to the control. No significant fouling was observed for the membrane. Conclusively, the combined two-stage AD process may offer an alternative approach for the treatment of nitrogen rich organic waste.

关键词： Rotating packed bed   Absorption   Natural aromas   Economics   Sensitivity analysis  

摘要： In this study, an economic evaluation of the Rotating Packed Bed (RPB) technology for the absorption of aromas from bioreactor off-gas was performed for different process scales based on experimental results for a model compound benzaldehyde. The comparison of the total annual costs of the RPB with the costs of a packed column showed that the RPB process is more expensive at all scales investigated. At the laboratory to pilot plant scale, the costs of the RPB contactor are higher than of packed columns. At the production scale, however, the RPB machine itself becomes cheaper than the packed column. The sensitivity analysis revealed that the main cost drivers influencing the investment decision are the equipment costs of the contactor and the blower, as well as the blower power required to overcome the pressure drop generated in the contactor. Although technically the RPB remains a promising alternative for the intensification of the product recovery from gaseous process streams, its economic benefits are questionable.

关键词： Azotobacter vinelandii   Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)   PHBV   Oxygen transfer rates   Valerate  

摘要： In the present study, the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by Azotobacter vinelandii was evaluated in shake flasks and bioreactors, utilizing different precursors and oxygen transfer rates (OTRs). In shake flask cultures, the highest PHBV yield from sucrose (0.16 g g(-1)) and 3-hydroxyvalerate (3HV) fraction in the PHA chain (27.4 mol%) were obtained with valerate (1.0 g L-1). In the bioreactor, the cultures were grown under oxygen-limited conditions, and the maximum OTR (OTRmax) was varied by adjusting the agitation rate. In the cultures grown at low OTRmax (4.3 mmol L-1 h(-1)), the intracellular content of PHBV (73% w w(-1)) was improved, whereas a maximum 3HV fraction (35 mol %) was obtained when a higher OTRmax (17.2 mmol L-1 h(-1), to 600 rpm) was employed. The findings obtained suggest that the PHBV production and the content of 3HV incorporated into the polymer were affected by the OTR. Based on the evidence, it is possible to produce PHBV with a different composition by varying the OTR of the culture;thus, the approach in this study could be used to scale up PHBV production.

关键词： ammonium-oxidizing bacteria   kinetic modeling   membrane bioreactor   nitrite-oxidizing bacteria   two-step nitrification  

摘要： A respirometric method for the kinetic modeling of ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was implemented in two membrane bioreactor (MBRA and MBRB) systems. These biological systems worked at mixed liquor suspended solids concentration of about 6.6 g L-1. MBRA worked at 6 hr of hydraulic retention time (HRT) and 20.7 degrees C, while the operational conditions for MBRB were 9.5 hr of HRT and 14.7 degrees C. Experimental data were fitted to the kinetic model with R-2 values of .9320 and .9250 for MBRA and MBRB, respectively. Both systems showed similar performances regarding organic matter and nitrogen removal. However, MBRB showed highest rates of carbon source degradation and net heterotrophic bacteria growth, and MBRA had highest rates of nitrogen source degradation and net autotrophic bacteria growth. This last system was characterized by values for Y-AOB, Y-NOB, mu(m,AOB) and mu(m,NOB) of 1.1749 mgVSS mgN(-1), 0.6473 mgVSS mgN(-1), 0.3664 hr(-1) and 0.1823 hr(-1), respectively.

关键词： Olive mill wastewater   Biological treatment   Bacillus subtilis   Phenolic compounds   Bioremediation   Optimization process  

摘要： Olive mill wastewater (OMWW) poses serious environmental problems due to the presence of high phenolic compounds (PC) content. The search for new strains able to degrade pollutants in OMWW and withstand the toxic effects of the high PC concentrations is of great scientific and industrial interest. In this study, an isolated bacterium identified as Bacillus subtilis was selected based on its ability to grow on minimum synthetic medium based media using PC as sole sources of carbon and energy and to degrade the OMWW. The treatment conditions were optimized and included the following parameters: OMWW dilution with the addition of different nitrogen sources, shaking and incubation temperatures. The maximum abatement rate of PC and chemical oxygen demand was 98% and 97%, respectively. This result was obtained at 25% dilution of OMWW with 1 mL inoculums size in a bioreactor with150 rpm, at 37 degrees C with the addition of the degradation media with 1 g/L yeast extract and 3 g/L urea. High-performance liquid chromatography analysis of extracts from treated OMWW showed the evolution of PC content during the degradation process and indicated the high reduction in phenolic compound concentrations.