18 research outputs found
Recommended from our members
Functional Stability of a Mixed Microbial Consortium Producing PHA From Waste Carbon Sources
Polyhydroxyalkanoates (PHAs) represent an environmentally-effective alternative to synthetic thermoplastics; however, current production practices are not sustainable. In this study, PHA production was accomplished in sequencing batch bioreactors utilizing real wastewaters and mixed microbial consortia from municipal activated sludge as inoculum. Polymer production reached 85%, 53%, and 10% of the cell dry weight from methanol-enriched pulp-and-paper mill foul condensate, fermented municipal primary solids, and biodiesel wastewater, respectively. Employing denaturing gradient gel electrophoresis of 16S-rDNA from PCR-amplified DNA extracts, distinctly different communities were observed between and within wastewaters following enrichment. Most importantly, functional stability was maintained despite differing and contrasting microbial populations
Recommended from our members
Functional Stability Of A Mixed Microbial Consortia Producing PHA From Waste Carbon Sources
Polyhydroxyalkanoates (PHAs), naturally-occurring biological polyesters that are microbially synthesized from a myriad of carbon sources, can be utilized as biodegradable substitutes for petroleum-derived thermoplastics. However, current PHA commercialization schemes are limited by high feedstock costs, the requirement for aseptic reactors, and high separation and purification costs. Bacteria indigenous to municipal waste streams can accumulate large quantities of PHA under environmentally controlled conditions; hence, a potentially more environmentally-effective method of production would utilize these consortia to produce PHAs from inexpensive waste carbon sources. In this study, PHA production was accomplished in sequencing batch bioreactors utilizing mixed microbial consortia from municipal activated sludge as inoculum, in cultures grown on real wastewaters. PHA production averaged 85%, 53%, and 10% of the cell dry weight from methanol-enriched pulp-and-paper mill foul condensate, fermented municipal primary solids, and biodiesel wastewater, respectively. The PHA-producing microbial consortia were examined to explore the microbial community changes that occurred during reactor operations, employing denaturing gradient gel electrophoresis (DGGE) of 16S-rDNA from PCR-amplified DNA extracts. Distinctly different communities were observed both between and within wastewaters following enrichment. More importantly, stable functions were maintained despite the differing and contrasting microbial populations
Exercise training meta-analysis of trials in patients with chronic heart failure (ExTraMATCH)
Objective To determine the effect of exercise training on survival in patients with heart failure due to left ventricular systolic dysfunction. Design Collaborative meta-analysis. Inclusion criteria Randomised parallel group controlled trials of exercise training, for at least eight weeks with individual patient data on survival for at least three months. Studies reviewed Nine datasets, totalling 801 patients: 395 received exercise training and 406 were controls. Main outcome measure Death from all causes. Results During a mean (SD) follow up of 705 (729) days there were 88 (22%) deaths in the exercise arm and 105 (26%) in the control arm. Exercise training significantly reduced mortality (hazard ratio 0.65, 95% confidence interval, 0.46 to 0.92; log rank chi(2) = 5.9; P = 0.015). The secondary end point of death or admission to hospital was also reduced (0.72, 0.56 to 0.93; log rank chi(2) = 6.4; P = 0.011). No statistically significant subgroup specific treatment effect was observed. Conclusion Meta-analysis of randomised trials to date gives no evidence that properly supervised medical training programmes for patients with heart failure might be dangerous, and indeed there is clear evidence of an overall reduction in mortality. Further research should focus on optimising exercise programmes and identifying appropriate patient groups to target