Chlorophenols are widespread and of environmental concern due to their toxic and carcinogenic properties. Development of less costly and less technically challenging remediation methods are needed; therefore, we developed a formulation based on micronized vermiculite that, when air-dried, resulted in a granular product containing the 4-chlorophenol (4-CP)-degrading Gram-positive bacterium Arthrobacter chlorophenolicus A6. This formulation and stabilization method yielded survival rates of about 60% that remained stable in storage for at least 3 months at 4 °C. The 4-CP degradation by the formulated and desiccated A. chlorophenolicus A6 cells was compared to that of freshly grown cells in controlled-environment soil microcosms. The stabilized cells degraded 4-CP equally efficient as freshly grown cells in two different set-ups using both hygienized and non-treated soils. The desiccated microbial product was successfully employed in an outdoor pot trial showing its effectiveness under more realistic environmental conditions. No significant phytoremediation effects on 4-CP degradation were observed in the outdoor pot experiment. The 4-CP degradation kinetics from both the microcosms and the outdoor pot trial were used to generate a predictive model of 4-CP biodegradation potentially useful for larger-scale operations, enabling better bioremediation set-ups and saving of resources. This study also opens up the possibility of formulating and stabilizing also other Arthrobacter strains possessing different desirable pollutant-degrading capabilities.
The effect of extraction method, pH and NaCl addition on rheological properties and microstructure of heat-induced faba bean protein gels was evaluated. Gels formed at pH 7 (no NaCl) of alkaline-extracted protein had the densest and finest network structure and highest stress and strain at fracture. The high density of nodes and small pores in the protein network could contribute to those mechanical properties. In contrast, storage modulus (G′) and Young's modulus were lowest for protein gels at pH 7. The gels formed at pH 5 had high G′ and Young's modulus, whereas stress and strain at fracture were lower, especially for gels formed from alkaline-extracted protein. Gels formed at pH 5 with 2% NaCl had two types of internal gel network, caused by a change in solubility of 7S globulins. When the protein powder was dissolved in water, particle size was dependent on the extraction method, with alkaline extraction giving much larger protein particles than soaked extraction.
The objective of this work was to investigate the performance and archaeal community of methanogenic digester under different temperatures (35°C, 55°C) and pH values (6.5, 7.0, 7.5, 8.0 and 8.5) in two-phase anaerobic digestion of pig manure and maize straw. The specific CH4 yields decreased by 22.6%, 60.0% and 94.1% for pH 7.5, 8.0 and 8.5 compared with pH 7.0 (277 N mLg-1CODadd) at 35°C, and decreased by 31.6%, 70.9% and 95.0% compared with pH 7.0 (253 N mLg-1CODadd) at 55°C The methane productions of mesophilic digestion at five pH levels were 13.6%, 9.7%, 24.1%, 50.8% and 30.0% higher than that of thermophilic digestion. Terminal restriction fragment length polymorphism (T-RFLP) analyses combined with clone library indicated that Methanosaeta and Methanosarcina were the dominant genus at 35°C and 55°C, respectively, and the relative abundance decreased significantly with the pH increasing from 7.5 to 8.5.