Differences between attached and suspended microalgal cells in ssPBR from the perspective of physiological properties.

Attached microalgae cultivation for the algae-based products is considered as a promising approach to simplify biomass recovery processes and reduce the cost. However, as an incipient research field, biomass accumulation is the mainly index for attached microalgal growth evaluation. To break through such limitations, physiological properties of attached microalgae (e.g. the oxygen evolving activity and the main organic composition of cells), which are important for microalgal growth evaluation but are still unclear in most studies, were studied using an attached microalgae culture system, i.e. suspended-solid phase photobioreactor (ssPBR) in this paper. As light, nutrients and other environmental conditions of attached microalgae were different from the suspended microalgae, physiological properties of attached microalgae also varied from the suspended ones. Besides the relatively lower biomass accumulation rate, attached microalgae also had a lower oxygen evolving activity (65% on average) comparing to suspended microalgae. The composition of microalgae changed towards accumulating more protein when suspended microalgae turned to attached status. The relative protein content of attached microalgae (50.1% ±â€¯10.1%) was approximately 30% higher than the suspended algae (36.0% ±â€¯16.1%) on average. The discovery of physiological properties of attached microalgae in this paper could help the production of high-protein microalgae-related products and explain some phenomenon during the production of microalgae-related products.

Elimination of disinfection byproduct formation potential in reclaimed water during solar light irradiation.

Ecological storage of reclaimed water in ponds and lakes is widely applied in water reuse. During reclaimed water storage, solar light can degrade pollutants and improve water quality. This study investigated the effects of solar light irradiation on the disinfection byproduct formation potential in reclaimed water, including haloacetonitriles (HANs), trichloronitromethane (TCNM), trihalomethanes (THMs), haloketones (HKs) and chloral hydrate (CH). Natural solar light significantly decreased the formation potential of HANs, TCNM, and HKs in reclaimed water, but had a limited effect on the formation potential of THMs and CH. Ultraviolet (UV) light in solar radiation played a dominant role in the decrease of the formation potential of HANs, TCNM and HKs. Among the disinfection byproducts, the removal kinetic constant of dichloroacetonitrile (DCAN) with irradiation dose was much larger than those for dichloropropanone (1,1-DCP), trichloropropanone (1,1,1-TCP) and TCNM. During solar irradiation, fluorescence spectra intensities of reclaimed water also decreased significantly. The removal of tyrosine (Tyr)-like and tryptophan (Trp)-like protein fluorescence spectra intensity volumes was correlated to the decrease in DCAN formation potential. Solar irradiation was demonstrated to degrade Trp, Tyr and their DCAN formation potential. The photolysis products of Trp after solar irradiation were detected as kynurenine and tryptamine, which had chloroform, CH and DCAN formation potential lower than those of Trp.

Inactivation and regrowth of antibiotic-resistant bacteria by PAA disinfection in the secondary effluent of a municipal wastewater treatment plant / 生物医学与环境科学（英文）

Inactivation and microbial regrowth of penicillin-, ampicillin-, cefalexin-, tetracycline-, chloramphenicol-, and rifampicin-resistant bacteria were studied to explore risks associated with selection and regrowth of antibiotic-resistant bacteria after PAA disinfection. The results showed that after exposure to 20 mg/L PAA for 10 min, inactivation of ampicillin-resistant bacteria reached 2.3-log, which was significantly higher than that of total heterotrophic bacteria with a decrease of 2.0-log. In contrast, inactivation of tetracycline- resistant bacteria was significantly less efficient, reaching only 1.1-log. Chloramphenicol-and tetracycline-resistant bacteria, as well as total heterotrophic bacteria regrew more than 10 fold compared to those in the untreated wastewater sample with 22 h stilling culture after exposure to 2 or 5 mg/L PAA as for 10 min. Selection and potential regrowth of tetracycline-and chloramphenicol-resistant bacteria are potential risks when utilizing PAA disinfection, which may induce the spread of specific antibiotic-resistant bacteria in reclaimed water.

Biomass production of a Scenedesmus sp. under phosphorous-starvation cultivation condition.

Microalgae-based bioenergy has gained extensive attention, but the consumption of non-renewable resource such as phosphorous is inevitable in the production of its feedstock. In this work, the minimal phosphorous consumption for algal biomass production of Scenedesmus sp. LX1 was investigated by monitoring the growth and nutrient uptake under two different cultivation modes: phosphorous-starvation and luxury-nutrient. The results showed that continuous nitrogen and phosphorous feeding in luxury-nutrient mode had no stimulating effect on biomass productivity at the nutrient level in this study, TN: 245 mg L(-1), TP: 5.4 mg L(-1). However, the sustained growth of biomass after the exhaust of phosphate in phosphorous-starvation mode led to significant increase in the biomass yield of phosphorous up to 160 g biomass/g -P, which was nearly six times more than that with nutrient feeding. To minimize phosphorous resource consumption in production of algal biomass, a phosphorous-starvation cultivation mode is proposed.

Culture of Scenedesmus sp. LX1 in the modified effluent of a wastewater treatment plant of an electric factory by photo-membrane bioreactor.

To investigate the coupled technology for advanced wastewater treatment and microalgal biomass production, a photo-membrane bioreactor was constructed. The microalga Scenedesmus sp. LX1 was cultured in the bioreactor using liquor prepared from the effluent of an electronic device factory. The algal cell growth, nitrate nitrogen removal, orthophosphate phosphorus removal were investigated. When cultured with batch operation, the average specific growth rate was about 0.09 d(-1), and low nitrogen (N), phosphorus (P) concentrations in the liquor were achieved. However, under continuous operation with an inflow of 60 Lh(-1), the average specific growth rate was only 0.02 d(-1), and removal rates of 100% for orthophosphate P and 46% for nitrate N were achieved. With the inflow of 120 Lh(-1), the accumulated metal ions in the bioreactor adversely affected the algal cells. The algal cells were much easier to settle, and the removal efficiency for N and P decreased.

Enhancement effect of ethyl-2-methyl acetoacetate on triacylglycerols production by a freshwater microalga, Scenedesmus sp. LX1.

Microalgae are very promising in biodiesel production. To reduce the production cost, approaches to enhance lipid and triacylglycerols (TAGs) production by microalgae have gained much attention. Effect of ethyl-2-methyl acetoacetate (EMA) on the lipid and TAGs production by a freshwater microalga, Scenedesmus sp. LX1, was studied in this paper. EMA below a concentration of 2 mg L(-1) had no significant effect on microalgal biomass or lipid production. The biomass and lipid productivity were about 0.47 g L(-1) and 139 mg L(-1), respectively, and the lipid content per biomass was about 30% (w/w). Promisingly, comparing with the one without EMA treatment, under EMA concentrations of 1.0-2.0 mg L(-1) the TAGs content per lipid (about 20% (w/w)) and TAGs productivity (about 23 mg L(-1)) were increased by 79% and 40%, respectively. Therefore, exposing algal cells with trace amount of EMA offers a viable method to enhance the TAGs production in Scenedesmus sp. LX1.

Lipid accumulation and nutrient removal properties of a newly isolated freshwater microalga, Scenedesmus sp. LX1, growing in secondary effluent.

Coupling of biodiesel production and wastewater treatment based on microalgae is a promising approach for handling the energy crisis of declining fossil fuel reserves. A freshwater microalga, Scenedesmus sp. LX1, isolated in a previous study, was tested for its ability to remove nutrients and accumulate lipid while growing in secondary effluent. Compared with 11 other species of high-lipid content microalgae obtained from the algae bank, Scenedesmus sp. LX1 adapted better to secondary effluent and achieved the highest biomass (0.11 gL(-1), dry weight) and lipid content (31-33%, dry weight). In secondary effluent, the specific growth rate (r) and maximum population growth rate (R(max)) of Scenedesmus sp. LX1 was 0.2 day(-1) and 0.23 x 10(6)cells (mL day)(-1), respectively, and inorganic nutrients could be efficiently removed by over 98% in 10 days. Upon a trigger of nitrogen deficiency on day 10, lipid content increased from 14% to 31%, and the highest lipid accumulation rate during cultivation was 0.008g(L day)(-1).

Biodegradation of gaseous chlorobenzene by white-rot fungus Phanerochaete chrysosporium / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To evaluate the effect of white rot fungus Phanerochaete chrysosporium on removal of gaseous chlorobenzene.</p><p><b>METHODS</b>Fungal mycelium mixed with a liquid medium was placed into airtight bottles. A certain amount of chlorobenzene was injected into the headspace of the bottles under different conditions. At a certain interval, the concentrations in the headspace were analyzed to evaluate the degradation of chlorobenzene by P. chrysosporium.</p><p><b>RESULTS</b>The degradation effects of P. chrysosporium on chlorobenzene under different conditions were investigated. The difference in the optimum temperature for the growth of the fungi and chlorobenzene degradation was observed. The data indicated that a lower temperature (28 degrees C) would promote the degradation of chlorobenzene than the optimum temperature for the growth of the fungi (37 degrees C). A low nitrogen source concentration (30 mg N/L) had a better effect on degrading chlorobenzene than a high nitrogen source concentration (higher than 100 mg N/L). A high initial concentration (over 1100 mg/m3) of chlorobenzene showed an inhibiting effect on degradation by P. chrysosporium. A maximum removal efficiency of 95% was achieved at the initial concentration of 550 mg/m3.</p><p><b>CONCLUSION</b>P. chrysosporium has a rather good ability to remove gaseous chlorobenzene. A low nitrogen source concentration and a low temperature promote the removal of chlorobenzene by P. chrysosporium. However, a high initial chlorobenzene concentration can inhibit chlorobenzene degradation.</p>

BACTERIAL QUINONE PROFILE FOR THE STUDY OF MICROBIAL COMMUNITY STRUCTURE IN ENVIRONMENTAL SAMPLES / 微生物学通报

Quinone is one of the electron transporters of the microbial respiratory chain. The dominant quinone of one species of bacteria is different from other bacteria. So the quinone profile of environmental samples can reflect the microbial community. This paper briefly introduces the analytical method used for microbial quinones. The microbial community in an activated sludge sample is studied using this method.

Isolation of a Bacterial Strain Capable of Carbamazepine-degrading and Biodegradation Characteristics / 微生物学通报

Quite recently,among new emerging contaminants,pharmaceutical and personal care products(PPCPs)and their active metabolites are an emerging environmental issue,due to their presence in the aquatic environment and potential for impacts on wildlife and humans.Carbamazepine is one of the most frequently and at the relatively high concentration levels detected pharmaceuticals in surface water and even in drinking water.Moreover,this drug has displayed high chronic ecotoxicity.A strain of carbamazepine-degrading bacterium was isolated from activated sludge treating pharmaceutical wastewater in Suzhou,China.It was identified as Acinetobacter sp.HY-7,based on biochemical test,16S rRNA and gyrB gene se-quence analysis.Strain HY-7 could grow in liquid mineral salt medium with carbamazepine as sole source of carbon,nitrogen and energy.HPLC analysis revealed the carbamazepine degradation percentage by HY-7 after 10 days was 48% at pH 6.0 and 25?C.Among carbamazepine and the similar structure compounds,in-dole,catechol,naphthalene,anthracene could also be utilized by strain HY-7 for growth,which exhibited a very broad substrate profile.