Bacterial Communities in the Sediments of Dianchi Lake, a Partitioned Eutrophic Waterbody in China

Bacteria play an important role in the decomposition and cycling of a variety of compounds in freshwater aquatic environments, particularly nutrient-rich eutrophic lakes. A unique Chinese eutrophic lake - Dianchi - was selected for study because it has two separate and distinct basins, Caohai with higher organic carbon levels and Waihai with lower organic carbon levels. Sediment bacterial communities were studied in the two basins using samples collected in each season from June 2010 to March 2011. Barcoded pyrosequencing based on the 16 S rRNA gene found that certain common phyla, Proteobacteria, Bacteroidetes, Firmicutes and Chloroflexi, were dominant in the sediments from both basins. However, from the class to genus level, the dominant bacterial groups found in the sediments were distinct between the two basins. Correlation analysis revealed that, among the environmental parameters examined, total organic carbon (TOC) accounted for the greatest proportion of variability in bacterial community. Interestingly, study results suggest that increasing allochthonous organic carbon could enhance bacterial diversity and biomass in the sediment. In addition, analysis of function genes (amoA and nosZ) demonstrated that ammonia-oxidizing bacteria (AOB) were dominant in sediments, with 99% belonging to Nitrosomonas. Denitrifying bacteria were comparatively diverse and were associated with some cultivatable bacteria

Nutrient recovery and microalgae biomass production from urine by membrane photobioreactor at low biomass retention times

Urine has been considered as an ideal nutrient source for microalgae cultivation thanks to its composition containing the high concentrations of nitrogen and phosphorus. Herein, the microalgae growth in urine was evaluated in a lab-scale membrane photobioreactor (MPBR) system. This work aimed to validate the influence of low biomass retention times (BRT) (10, 7, 5, 3, 2 d) on nutrient remediation and biomass productivity. It revealed that BRT of 7 d resulted in synergistically high biomass production (biomass productivity of 313 mg/L.d) and removal rates (TN of 90.5 mg/L.d and TP of 4.7 mg/L.d). Notably, the short BRT of 2–5 d was not sufficient to trigger actively growing microalgae and thus reduced biomass production rate. In addition, as operated at a low flux of 2 L/m2.h, MPBR system required no physical cleaning for 100 days of operation. The BRT-dependent biomass concentration played a pivotal role in changing the fouling rate of MPBR; however, the fouling is reversible in the MPBR system under the low flux condition

Evaluation of microporous polycaprolactone matrices for controlled delivery of antiviral microbicides to the female genital tract

Acyclovir (ACV) as a model antiviral microbicide, was incorporated in controlled-release polycaprolactone (PCL) matrices designed for application as intra-vaginal ring inserts (IVRs). Microporous materials incorporating acyclovir up to a level of similar to 10 % w/w were produced by rapidly cooling suspensions of drug powder in PCL solution followed by solvent extraction from the hardened matrices. Around 21, 50 and 78 % of the drug content was gradually released from matrices over 30 days in simulated vaginal fluid at 37 A degrees C, corresponding to drug loadings of 5.9, 7.0 and 9.6 % w/w. The release behaviour of matrices having the lowest drug loading followed a zero order model, whereas, the release kinetics of 7.0 and 9.6 % ACV-loaded PCL matrices could be described effectively by the Higuchi model, suggesting that Fickian diffusion is controlling drug release. Corresponding values of the diffusion co-efficient for ACV in the PCL matrices of 3.16 x 10(-9) and 1.07 x 10(-8) cm(2)/s were calculated. Plaque reduction assays provided an IC50 value of 1.09 mu g/mL for acyclovir against HSV-2 and confirmed the antiviral activity of released acyclovir against HSV-2 replication in primate kidney cells (Vero) at levels similar to 70 % that of non-formulated acyclovir at day 30. Estimated minimum in vivo acyclovir concentrations produced by a PCL IVR (19 mu g/mL) exceeded by a factor of 20 the IC50 value against HSV-2 and the reported ACV vaginal concentrations in women (0.5-1.0 mu g/mL) following oral administration. These findings recommend further investigations of PCL matrices for vaginal delivery of antiviral agents in the treatment and prevention of sexually transmitted infections such as AIDS