Assessment of the biodegradation of doxycycline by biostimulation with addition of glucose, phenol or/and copper

Doxycycline, an antibiotic, is largely used in human and veterinary medicine. The conventional treatment with activated sludge is not very efficient. Laccase appeared to be the main enzyme secreted essentially by white rot fungi as Trametes versicolor and Phlebia fascicularia on the degradation of xenobiotic compounds from the pharmaceutical industry. The main purpose of this study was to enhance the biodegradation of doxycycline through activated sludge combined with addition of glucose as a carbon co-substrate to improve the growth of the microbial population present in the activated sludge, phenol as a laccase mediator, copper as a cofactor and inductor for laccase production. The enhancement of the biodegradation of doxycycline was 50, 90, 68 and 83% greater respectively with the addition of glucose, copper, phenol and with a mixture of the compounds after 14 days of treatment at 25°C. Compared with the biotic control (activated sludge alone), a 30% increase for the test with the addition of phenol was observed.

Carbon Material with High Specific Surface Area Improves Complex Copper Ores’ Bioleaching Efficiency by Mixed Moderate Thermophiles

The catalysis of carbon materials with different specific surface areas (SSA) (2, 400, 800 and 1200 m2/g) on complex copper ores bioleaching by moderately mixed thermophiles was investigated. The copper extractions increased with the rise in SSA of carbon materials. A recovery of 98.8% copper in the presence of 1200 m2/g activated carbon was achieved, and improved by 30.7% and 76.4% compared with biotic control and chemical leaching. Moreover, the addition of 1200 m2/g activated carbon adsorbed large amount of bacteria, accelerated the oxidation rate of ferrous iron and maintained the solution redox potential at relatively low values, and significantly increased the dissolution of primary copper sulfide (62.7%) compared to biotic control (6.0%). Microbial community succession revealed that activated carbon changed the microbial community composition dramatically. The S. thermosulfidooxidans ST strain gained a competitive advantage and dominated the microbial community through the whole bioleaching process. The promoting effect of carbon material with higher SSA on copper extraction was mainly attributed to better galvanic interaction, biofilm formation, direct contact and lower redox potential.

Analysis of biological and meteorological controls of evapotranspiration in pristine forests and a pasture site in Amazonia

This work studied the behavior and seasonality of evapotranspiration influenced by biotic and abiotic factors through analysis of diurnal variation of aerodynamic resistance (ra), stomatal resistance (rs) and decoupling factor (Ω). This index was proposed by Jarvis and McNaughton (1986) as an indicative of the control of these resistances on the evapotranspiration of vegetation. Selection of representative data from wet and dry seasons from a primary forest in Central Amazonia and a primary forest and a pasture sites in Southwestern Amazonia had shown that: (i) ra is about 20 s.m-1 in both forests in both seasons, and ranges from 70 to 100 s.m-1 in the pasture site; (ii) rs varies both throughout the day and seasonally, with medians increasing from 40 in the morning, to 150 s.m-1 in late afternoon, in the wet season in the forests and from 50 to 160 s.m-1 in the pasture. These values increase in the dry season, with the forests rs ranging from 50 up to 500 s.m-1 and pasture rs starting from 140 s.m‑1 and reaching up to more than 1800 s.m-1 in the dry afternoons; (iii) Ω ranges from 0.5 to 0.8 during the wet season, and reduces to values below 0.5 in the afternoons during the dry season, indicating that, although a strong influence of net radiation in the evaporative loss is present, to a large extent the evapotranspiration fluxes are coupled to the biotic control of stomatal closure in the vegetation, especially in the pasture and during dry periods.

Electrical Stimulation Improves Microbial Salinity Resistance and Organofluorine Removal in Bioelectrochemical Systems

ABSTRACTFed batch bioelectrochemical systems (BESs) based on electrical stimulation were used to treatp-fluoronitrobenzene (p-FNB) wastewater at high salinities. At a NaCl concentration of 40 g/liter,p-FNB was removed 100% in 96 h in the BES, whereas in the biotic control (BC) (absence of current),p-FNB removal was only 10%. By increasing NaCl concentrations from 0 g/liter to 40 g/liter, defluorination efficiency decreased around 40% in the BES, and in the BC it was completely ceased.p-FNB was mineralized by 30% in the BES and hardly in the BC. Microorganisms were able to store 3.8 and 0.7 times more K+and Na+intracellularly in the BES than in the BC. Following the same trend, the ratio of protein to soluble polysaccharide increased from 3.1 to 7.8 as the NaCl increased from 0 to 40 g/liter. Both trends raise speculation that an electrical stimulation drives microbial preference toward K+and protein accumulation to tolerate salinity. These findings are in accordance with an enrichment of halophilic organisms in the BES.Halobacteriumdominated in the BES by 56.8% at a NaCl concentration of 40 g/liter, while its abundance was found as low as 17.5% in the BC. These findings propose a new method of electrical stimulation to improve microbial salinity resistance.