关键词： antimicrobial activity   biopolymer   food packaging   gallic acid (GA)   Polyhydroxybutyrate   potassium sorbate  

摘要： Polyhydroxybutyrate (PHB) has gained attention as an excellent packaging material due to its high crystallinity, biodegradability, low interaction with food matrices, and favorable mechanical properties. This study explores the development of PHB films incorporated with potassium sorbate (KS) and gallic acid (GA) via solvent casting, followed by a 30-day biodegradation test in soil. The films are analyzed for physicochemical and microbiological properties using X-ray diffraction, tensile testing, and disk diffusion assays. The soil-buried PHB films demonstrate accelerated biodegradation, likely driven by increased microbial and fungal activity, as well as moisture absorption. Incorporating KS and GA significantly enhances the antimicrobial efficacy of the films against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, with greater inhibition observed against S. aureus. This difference may stem from the additional lipopolysaccharide membrane in E. coli. Field emission scanning electron microscopy (FESEM) of the films, both pre- and post-biodegradation, provides further insights into their structural changes. These findings underscore the potential of PHB antimicrobial films in advancing sustainable food packaging applications.

关键词： Cyanobacteria   Nostoc sp. PCC7120   Sustainable PHB production   Genetic engineering  

摘要： During the past decades, the importance of developing sustainable, carbon dioxide (CO2)-neutral and biodegradable alternatives to conventional plastic has become evident in the context of global pollution issues. Therefore, heterotrophic bacteria such as Cupriavidus sp. have been intensively explored for the synthesis of the biodegradable polymer polyhydroxybutyrate (PHB). PHB is also naturally produced by a variety of phototrophic cyanobacteria, which only need sunlight and CO2, thereby allowing a CO2 negative, eco-friendly synthesis of this polymer. However, a major drawback of the use of cyanobacteria is the need of a two-stage production process, since relevant amount of PHB synthesis only occurs after transferring the cultures to conditions of nitrogen starvation, which hinders continuous, large-scale *** study aimed at generating, by means of genetic engineering, a cyanobacterium that continuously produces PHB in large amounts. We choose a genetically amenable filamentous cyanobacterium of the genus Nostoc sp., which is a diazotrophic cyanobacterium, capable of atmospheric nitrogen (N2) fixation but naturally does not produce PHB. We transformed this Nostoc strain with various constructs containing the constitutive promotor PpsbA and the PHB synthesis operon phaC1AB from Cupriavidus necator H16. In fact, while the transformants initially produced PHB, the PHB-producing strains rapidly lost cell viability. Therefore, we next attempted further optimization of the biosynthetic gene cluster. The PHB operon was expanded with phasin gene phaP1 from Cupriavidus necator H16 in combination with the native intergenic region of apcBA from Nostoc sp. 7120. Finally, we succeeded in stabilized PHB production, whilst simultaneously avoiding decreasing cell viability. In conclusion, the recombinant Nostoc strain constructed in the present work constitutes the first example of a continuous and stable PHB production platform in cyanobacteria, which has been decouple

关键词： cell sizes   ClpXP   Halomonas   morphology engineering   mreB   next generation industrial biotechnology   PHB  

摘要： Most bacterial cells are 1-2 microns in size, limiting intracellular products like polyhydroxyalkanoates (PHA) accumulation. Cell size is regulated by key genes such as mreB and minCD, which encode cellular skeleton protein and control cell fission ring location, respectively. Their expression changes significantly affect microbial growth. This study successfully redesigns the ClpXP protein degradation system by deleting the sspB gene and using mutated SsrA tags with different degradation rates to control MreB degradation. Dynamic degradation of MreB allows non-model bacterium Halomonas bluephagenesis to grow normally and increase cell size simultaneously. Combined with overexpression of minCD, H. bluephagenesis with progressive MreB degradation increases the cell size further, albeit with a reduced growth rate. H. bluephagenesis CYL0307, with the PHB granule-associated protein PhaP1 deleted and phaABRe overexpressed in the MreB-degraded strain, increases cell volume more than nine times compared to the original strain. CYL0307 produces 149 g L-1 cell dry weight containing 82% PHB after 44 h in a 5000 L bioreactor, with cells containing single large PHB granules, simplifying recovery and purification. These results provide a post-translational gene regulation method in H. bluephagenesis and a strategy for enhancing PHB production via morphological engineering.

关键词： Mitophagy   PHB2   PINK1   PRKN   Salmonella Typhimurium   SseJ  

摘要： Despite decades of research on effective methods to resist Salmonella enterica serovar Typhimurium (S. Typhimurium) pathogenicity, the mechanisms of S. Typhimurium-host interactions have not been fully determined. S. Typhimurium is characterized as an important zoonosis in public health worldwide because of its endemicity, high morbidity, and difficulty in applying control and prevention measures. Herein, we introduce a novel bacterial factor, secretion system effector J (SseJ), and its interactive host protein, PHB2 (prohibitin 2). We explored whether SseJ affected S. Typhimurium replication and survival in the host. S. Typhimurium infection caused severe mitochondrial damage and mitophagy, which facilitated S. Typhimurium proliferation in cells. S. Typhimurium SseJ activated the PINK1 (PTEN induced kinase 1)-PRKN (parkin RBR E3 ubiquitin protein ligase)-autophagosome-dependent mitophagy pathway, aided by the mitophagy receptor PHB2, for bacterial survival and persistent infection. Moreover, suppression of mitophagy alleviated the pathogenicity of S. Typhimurium. In conclusion, S. Typhimurium infection could be antagonized by targeting the SseJ-PHB2-mediated host mitochondrial autophagy ***: ACTB: actin beta;BafA1: bafilomycin A1;CCCP: carbonyl cyanide m-chlorophenyl hydrazone;co-IP: co-immunoprecipitation;CFU: colony-forming units;COX4/COXIV: cytochrome c oxidase subunit 4;CQ: chloroquine;hpi: h post-bacterial infection;MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta;Mdivi-1:mitophagy inhibitor mitochondrial division inhibitor 1;MFN2: mitofusin 2;MG132: z-leu-leu-leucinal;MOI: multiplicity of infection;mtDNA: mitochondrial DNA;PBS: phosphate-buffered saline;PGAM5: PGAM family member 5, mitochondrial serine/threonine protein phosphatase;PHB2: prohibitin 2;PINK1: PTEN induced kinase 1;qPCR: quantitative real-time reverse transcription PCR;Roc-A: Rocaglamide A;PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase;SCVs: Salmonella-con

关键词： 城镇污水处理厂   长江经济带   生态效率   数据包络分析  

摘要： 污水处理厂被认为是通过消耗资源降解污染物的生产单位，是典型的高能耗行业和高温室气体排放源。由于水资源短缺和日益严格的污水排放标准，污水处理厂出现“以高能耗换取高水质”的现象，然而简单的污染物削减量指标或归一化的能耗、碳排放当量指标难以全面评估污水处理厂对生态环境的影响。本研究采用基于归一化的碳排放当量和基于数据包络分析的生态效率指标，对长江经济带的633座城镇污水处理厂进行评估，其生态效率指数均值为0.492。长江经济带污水处理厂的生态效率受规模效应影响显著；各地区、各工艺污水处理厂生态效率存在较大差异，其中间歇流反应器或全混合反应器生态效率较高；随着污水处理厂进水BOD5浓度的升高，其生态效率呈现先升高后降低的变化趋势；深度处理将加剧污水处理系统对生态环境的影响。本研究可为建设高质量城市污水处理体系提供理论依据。

关键词： 碳排放   污水处理系统   提标改造   污泥处置   碳减排  

摘要： 污水处理系统是城市碳排放的重要排放源，随着污水排放标准越来越高，明确污水处理厂提标改造对碳排放的影响十分重要。以典型的厌氧/缺氧/好氧(A2/O)生物处理工艺为研究对象，以西安市某污水厂为例，基于《IPCC国家温室气体清单指南》和碳排放因子法，对提标改造前后污水处理系统的碳排放进行了估算。结果表明，污水处理厂提标改造后，COD、BOD5、NH3-N和TP的去除率达到了95%及以上。污水处理系统年总碳排放(以CO2-eq计，下同)增加了15065.65 t，吨水碳排放增加了0.103 kg，吨水处理成本增加了0.14元。污水厂污水处理过程中直接碳排放强度为0.083 kg·m-3，较改造前增加了9.19%；间接碳排放强度为0.412 kg·m-3，较改造前增加了25.8%；污水处理直接碳排放和间接碳排放分别占16.82%和83.18%。污泥处理直接碳排放强度为0.246 kg·m-3，较改造前增加了4.98%；间接碳排放强度为0.0047 kg·m-3，较改造前增加了4.73%；污泥处理直接碳排放间接碳排放分别占98.11%和1.89%。在污水处理厂内建立光伏发电站，将DO和NO2-N的浓度控制在一定范围，或建立污泥消化池并利用沼气热电联产，能使污水处理厂达到降碳目的。

关键词： 混合污水处理   BFBR立体生态技术   地下式水厂   生态景观花园   工业园区  

摘要： 珠海市某工业园区混合污水处理厂设计规模为5×10～4 m3/d，项目定位高、水质成分及结构形式复杂、处理、设计和建设难度大、出水标准要求严苛。设计采用地下式水处理+地上式生态景观花园打造相结合的建设模式。针对含镍废水、生产废水、生活污水混合性质的水质，处理工艺采用混凝沉淀、芬顿氧化、臭氧氧化、离子树脂交换、BFBR立体生态技术、连续砂滤等组合方式。实际运行出水污染物指标浓度远低于排放标准，工艺系统处理效好，COD、NH3-N、TN、TP、TNi、TCu平均去除率分别达到81.9%、99.7%、69.3%、91.1%、81.7%、85.9%。

关键词： 集成污水处理技术   含油污水   超低排放   环保  

摘要： 陕西延长石油(集团)有限责任公司延安石油化工厂根据污水处理场特点及运行现状,使用集成污水处理技术进一步对低、高浓度含油污水、总排水进行综合处理,实现污染物超低排放。改造后,年平均COD为13.5 mg/L,BOD为2.74 mg/L,氨氮质量浓度为0.13 mg/L,总氮质量浓度为6.82 mg/L,总磷质量浓度为0.06 mg/L,石油类质量浓度为0.75 mg/L,满足《陕西省黄河流域污水综合排放标准》(DB 61/224-2018)要求。

关键词： 污水处理厂   间接碳排放   电力消耗   药剂消耗  

摘要： 污水处理厂间接碳排放是污水处理系统碳排放的主要排放源,对污水处理系统碳排放的贡献较大。为了探明污水处理厂间接碳排放的主要排放来源,对广东省某污水处理厂间接碳排放量核算及分析。结果表明,广东省污水处理厂间接碳排放量由高到低分别为电力消耗、PAC消耗和PAM消耗,且电力消耗产生的碳排放占间接碳排放总量的95.21%,PAC和PAM消耗产生的药剂消耗碳排放仅占间接碳排放总量的4.79%。回归分析结果表明,单位电力消耗量和PAM消耗量均与污水处理厂日处理量之间存在极显著的负相关关系(p<0.01),单位PAC消耗量与污水处理厂日处理量之间存在显著的负相关关系(p<0.05)。因此,以期通过对污水处理厂间接碳排放进行核算分析,为同类污水处理厂的间接碳减排提供参考。