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Two bacterial strains Klebsiella oxytoca Sc and Methylobacterium mesophilicum Sr were isolated and identified from enrichment cultures using dimethyl isophthalate (DMI) as the sole source of carbon and energy, and mangrove sediment as an inoculum. DMI was rapidly transformed by K. oxytoca Sc in the culture with formation of monomethyl isophthalate (MMI), which accumulated in the culture medium. M. mesophilicum Sr, incapable of utilizing DMI, showed high capability of degrading MMI to a transitory intermediate isophthalic acid (IPA), which was further mineralized by this strain. The biochemical pathway of DMI degradation by these two bacteria in a consortium was proposed: DMI to MMI by K. oxytoca Sc, MMI to IPA by M. mesophilicum Sr, and IPA by both K. oxytoca Sc and M. mesophilicum Sr based on the identified degradation intermediates. The consortium comprising K. oxytoca Sc and M. mesophilicum Sr was effective in mineralization of DMI. The results suggest that complete degradation of environmental pollutant DMI requires the biochemical cooperation between different microorganisms of the mangrove environment. [Copyright &y& Elsevier]

Cultures of Scytonema javanicum obtained from artificial medium are used to control desertification, and through the effective redistribution of nutrients, related environmental problems can be alleviated. Wastewater is considered to be a potential alternative medium for S. javanicum. However, the effect of temperature on the nutrient redistribution ability of S. javanicum cultured in wastewater has rarely been considered. Therefore, this study explores the effect of temperature on S. javanicum in wastewater. The results showed that a sufficient temperature increase (from 25 °C to 30 °C) increased the photosynthetic activity of photosynthetic system II (PSII), accelerated the accumulation rate of S. javanicum biomass, and improved the removal efficiency of nutrients in wastewater. However, an increasing temperature caused a decrease in the final accumulated biomass. When the temperature was above 35 °C, the ratio of the variable to maximal fluorescence (Fv/Fm) of S. javanicum decreased, thus, causing damage to PSII. The average Fv/Fm at 35 °C and 40 °C decreased by 10.49% and 72.37%, respectively, compared to that at 25 °C. By analysing the chlorophyll fluorescence induction kinetics (OJIP) curve after 30 days, the P phase at 30 °C increased by 15.47% relative to that at 25 °C, whereas that at 35 °C and 40 °C decreased by 45.54% and 86.37%, respectively. In particular, at 40 °C, the O-J-I-P phase transformed into the O-J (J = I = P) phase, which caused irreversible damage to the PSII of S. javanicum. Comprehensive scores were determined using the entropy weight method and revealed that 30 °C was the optimal temperature for the wastewater culture of S. javanicum. This temperature improved the biomass accumulation rate and wastewater transfer efficiency. These results provide a scientific basis for improving the efficiency of the coupling technology of wastewater treatment and desert algal cultivation. Unlabelled Image • Accelerating the transformation of wastewater pollution to desert resources. • Increasing the temperature (< 35 °C) can accelerate biomass accumulation and nutrient redistribution. • The time to reach the maximum biomass at 30 °C was shortened to 25d. • Temperature exceeding 35 °C will cause serious damage to PSII system. • 30 °C is more suitable for long-term operation (> 150 d). [ABSTRACT FROM AUTHOR]

In this work, in-situ remediation of sediment was carried out by combining various methods. The results showed that the treatment effect of Calcium nitrate + composite functional microorganisms + Low-DO (dissolved oxygen) aeration (CN/CFM/LDA) was the best, in which 2.5 g calcium nitrate, 1 g functional bacteria and intermittent aeration (0.1 m3/h, 3 h per day) were utilized for the remediation of 500 g sediments within 40-day experimental period. The DO and oxidation reduction potential (ORP) in overlying water have been improved from 3.23 mg/L to 4.4 mg/L and 25.8 mV to 112.4 mV, respectively. The release fluxes of ammonia nitrogen (NH 4 +-N), nitrite nitrogen (NO 2 −-N) and nitrate nitrogen (NO 3 −-N) were respectively reduced by 30.51%, 13.11% and 77.45% compared with the control and the removal rate of the acid volatile sulfide (AVS) in sediments was 94.14% compared with the original sample. The results of high-throughput sequencing show that the dominant bacterial community in CN/CFM/LDA was transformed into Proteobacteria (relative abundance of 74.17%) at the phylum level and Thiobacillus (relative abundance of 38.52%) at the genus level. The results of 16S functional prediction indicated that the remediation method can enhance the numbers of microbial key enzymes (92360) in the nitrification and denitrification process, where Low-DO aeration can mediate the growth of denitrifying bacteria and promote the performance of key enzymes. In conclusion, the experimental results show that the use of calcium nitrate and composite functional microorganisms under low-DO regulation has a promising remediation effect on sediments of black-malodorous water. Unlabelled Image • A novel method of combination of repair agents and Low-DO aeration to mitigate the release of nitrogen into water. • The color of the sediments also changed from black to yellowish brown. • The dominant bacterial community in sediments transformed into Proteobacteria at the phylum level. • Low-DO aeration can mediate the growth of denitrifying bacteria and promote the performance of key enzymes. [ABSTRACT FROM AUTHOR]