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Wen Q, Wang Z, Liu B, Liu S, Huang H, Chen Z. Enrichment performance and salt tolerance of polyhydroxyalkanoates (PHAs) producing mixed cultures under different saline environments. ENVIRONMENTAL RESEARCH 2024; 251:118722. [PMID: 38499223 DOI: 10.1016/j.envres.2024.118722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/08/2024] [Accepted: 03/12/2024] [Indexed: 03/20/2024]
Abstract
The key to the resource recycling of saline wastes in form of polyhydroxyalkanoates (PHA) is to enrich mixed cultures with salt tolerance and PHA synthesis ability. However, the comparison of saline sludge from different sources and the salt tolerance mechanisms of salt-tolerant PHA producers need to be clarified. In this study, three kinds of activated sludge from different salinity environments were selected as the inoculum to enrich salt-tolerant PHA producers under aerobic dynamic feeding (ADF) mode with butyric acid dominated mixed volatile fatty acid as the substrate. The maximum PHA content (PHAm) reached 0.62 ± 0.01, 0.62 ± 0.02, and 0.55 ± 0.03 g PHA/g VSS at salinity of 0.5%, 0.8%, and 1.8%, respectively. Microbial community analysis indicated that Thauera, Paracoccus, and Prosthecobacter were dominant salt-tolerant PHA producers at low salinity, Thauera, NS9_marine, and SM1A02 were dominant salt-tolerant PHA producers at high salinity. High salinity and ADF mode had synergistic effects on selection and enrichment of salt-tolerant PHA producers. Combined correlation network with redundancy analysis indicated that trehalose synthesis genes and betaine related genes had positive correlation with PHAm, while extracellular polymeric substances (EPS) content had negative correlation with PHAm. The compatible solutes accumulation and EPS secretion were the main salt tolerance mechanisms of the PHA producers. Therefore, adding compatible solutes is an effective strategy to improve PHA synthesis in saline environment.
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Affiliation(s)
- Qinxue Wen
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin, 150090, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Zifan Wang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin, 150090, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Baozhen Liu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, China
| | - Shaojiao Liu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin, 150090, China; School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou, 510006, China
| | - Haolong Huang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin, 150090, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Zhiqiang Chen
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin, 150090, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
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Zhou J, Li D, Zhang X, Liu C, Chen Y. Valorization of protein-rich waste and its application. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 901:166141. [PMID: 37586528 DOI: 10.1016/j.scitotenv.2023.166141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 08/05/2023] [Accepted: 08/06/2023] [Indexed: 08/18/2023]
Abstract
Energy shortages present significant challenges with the rising population and dramatic urbanization development. The effective utilization of high-value products generated from massive protein-rich waste has emerged as an excellent solution for mitigating the growing energy crisis. However, the traditional disposal and treatment of protein-rich waste, have been proven to be ineffective in resource utilization, which led to high chemical oxygen demand and water eutrophication. To effectively address this issue, hydrolysate and bioconversion products from protein-rich waste have been widely investigated. Herein, we aim to provide an overview of the valorization of protein-rich waste based on a comprehensive analysis of publicly available literature. Firstly, the sources of protein-rich waste with various quantities and qualities are systematically summarized. Then, we scrutinize and analyze the hydrolysis approaches of protein-rich waste and the versatile applications of hydrolyzed products. Moreover, the main factors influencing protein biotransformation and the applications of bioconversion products are covered and extensively discussed. Finally, the potential prospects and future directions for the valorization of protein-rich waste are proposed pertinently.
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Affiliation(s)
- Jing Zhou
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Dapeng Li
- School of Environment Science and Engineering, Suzhou University of Science and Technology, 1 Kerui Road, Suzhou 215009, China
| | - Xuemeng Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Chao Liu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
| | - Yinguang Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
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Polyhydroxyalkanoates Production by Mixed Microbial Culture under High Salinity. SUSTAINABILITY 2022. [DOI: 10.3390/su14031346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The fishing industry produces vast amounts of saline organic side streams that require adequate treatment and disposal. The bioconversion of saline resources into value-added products, such as biodegradable polyhydroxyalkanoates (PHAs), has not yet been fully explored. This study investigated PHA production by mixed microbial cultures under 30 gNaCl/L, the highest NaCl concentration reported for the acclimatization of a PHA-accumulating mixed microbial culture (MMC). The operational conditions used during the culture-selection stage resulted in an enriched PHA-accumulating culture dominated by the Rhodobacteraceae family (95.2%) and capable of storing PHAs up to 84.1% wt. (volatile suspended solids (VSS) basis) for the highest organic loading rate (OLR) applied (120 Cmmol/(L.d)). This culture presented a higher preference for the consumption of valeric acid (0.23 ± 0.03 CmolHVal/(CmolX.h)), and the 3HV monomer polymerization (0.33 ± 0.04 CmmolHV/(CmmolX.h) was higher as well. As result, a P(3HB-co-3HV)) with high HV content (63% wt.) was produced in the accumulation tests conducted at higher OLRs and with 30 gNaCl/L. A global volumetric PHA productivity of 0.77 gPHA/(L.h) and a specific PHA productivity of 0.21 gPHA/(gX.h) were achieved. These results suggested the significant potential of the bioconversion of saline resources into value-added products, such as PHAs.
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