Characterization and biodegradation kinetics of a new cold-adapted carbamazepine-degrading bacterium, Pseudomonas sp. CBZ-4

Carbamazepine is frequently detected in waters and hardly eliminated during conventional wastewater treatment processes due to its complicated chemical structure and resistance to biodegradation. A carbamazepine-degrading bacterium named CBZ-4 was isolated at a low temperature （10℃） from activated sludge in a municipal wastewater treatment plant. Strain CBZ-4, which can use carbamazepine as its sole source of carbon and energy, was identified as Pseudomonas sp. by the 16S rRNA gene sequence. The composition and percentage of fatty acids, which can reveal the cold-adaptation mechanism of strain CBZ-4, were determined. Strain CBZ-4 can effectively degrade carbamazepine at optimal conditions： pH 7.0, 10℃, 150 r/min rotation speed, and 13% inoculation volume. The average removal rate of carbamazepine was 46.6% after 144 hr of incubation. The biodegradation kinetics of carbamazepine by CBZ-4 was fitted via the Monod model. Vmax and Ks were found to be 0.0094 hr^-1 and 32.5 mg/L, respectively.

Improvement of nitrification efficiency by bioaugmentation in sequencing batch reactors at low temperature

Bioaugmentation is an effective method of treating municipal wastewater with high ammonia concentration in sequencing batch reactors （SBRs） at low temperature （10℃）. The cold-adapted ammonia- and nitrite- oxidizing bacteria were enriched and inoculated, respectively, in the bioaugmentation systems. In synthetic wastewater treatment systems, the average NH4＋-N removal efficiency in the bioaugmented system （85%） was much higher than that in the unbioaugmented system. The effluent NH4＋ -N concentration of the bioaugmented system was stably below 8 mg. L1 after 20 d operation. In municipal wastewater systems with bioaugmentation, the effluent NH4＋- -N concentration was below 8 mg·L^-1 after 15 d operation. The average NH4＋ -N removal efficiency in unbioaugmentation system （about 82%） was lower compared with that in the bioaugmentation system. By inoculating the cold-adapted nitrite-oxidizing bacteria （NOB） into the SBRs after 10 d operation, the nitrite concentration decreased rapidly, reducing the NO2 -N accumulation effectively at low temperature. The func- tional microorganisms were identified by PCR-DGGE, including uncultured Dechloromonas sp., uncultured Nitrospira sp., Clostridium sp. and uncultured Thauera sp. The results suggested that the cold-adapted microbial agent of ammonia-oxidizing bacteria （AOB） and NOB could accelerate the start-up and promote achieving the stable operation of the low-temperature SBRs for nitrification.

Insight into microbial synthesis of metal nanomaterials and their environmental applications:Exploration for enhanced controllable synthesis

Microbial fabrication of metal nanoparticles(MNPs)has received significant attention due to the advantages of low toxicity,energy efficiency and ecological safety.Diverse groups of MNPs can be synthesized intracellularly or extracellularly by various wild-type microorganisms,including bacteria,fungi,algae and viruses.Synthetic biology approaches,represented by genetic engineering,have been applied to overcome the shortcomings in productivity,stability,and controllability of biosynthetic MNPs.Scanning electron microscope(SEM),transmission electron microscope(TEM)and other characterization techniques assist in deciphering their unique properties.In addition,biosynthetic MNPs have been widely explored for the utilization in environmental remediation and contaminant detection.And machine learning contains a great potential for designing targeted MNPs and predicting their toxicity.This review provides a comprehensive overview of the research progress in the microbial synthesis of MNPs.An outlook on the current challenges and future prospects in the biologically controllable synthesis and engineering environmental applications of MNPs is also provided in this review.