Ammonia-oxidizers' diversity in wastewater treatment processes.

The diversity of ammonia-oxidizing bacteria (AOB) within the beta-subclass of Proteobacteria was investigated by genus- and family-specific real-time quantitative PCR (qPCR) assays on samples drawn from wastewater treatment systems. The 16S rRNA gene copy numbers ranged from 7.0 × 10 to 6.

Microalgae-mediated simultaneous treatment of toxic thiocyanate and production of biodiesel.

In this work, a method for simultaneously degrading the toxic pollutant, thiocyanate, and producing microalgal lipids using mixed microbial communities was developed. Aerobic activated sludge was used as the seed culture and thiocyanate was used as the sole nitrogen source. Two cultivation methods were sequentially employed: a lithoautotrophic mode and a photoautotrophic mode.

Quantitative real-time PCR approaches for microbial community studies in wastewater treatment systems: applications and considerations.

Quantitative real-time PCR (qPCR) has been widely used in recent environmental microbial ecology studies as a tool for detecting and quantifying microorganisms of interest, which aids in better understandings of the complexity of wastewater microbial communities. Although qPCR can be used to provide more specific and accurate quantification than other molecular techniques, it does have limitations that must be considered when applying it in practice. This article reviews the principle of qPCR quantification and its applications to microbial ecology studies in various wastewater treatment environments.

Methods of downstream processing for the production of biodiesel from microalgae.

Despite receiving increasing attention during the last few decades, the production of microalgal biofuels is not yet sufficiently cost-effective to compete with that of petroleum-based conventional fuels. Among the steps required for the production of microalgal biofuels, the harvest of the microalgal biomass and the extraction of lipids from microalgae are two of the most expensive. In this review article, we surveyed a substantial amount of previous work in microalgal harvesting and lipid extraction to highlight recent progress in these areas.

Effect of temperature and hydraulic retention time on volatile fatty acid production based on bacterial community structure in anaerobic acidogenesis using swine wastewater.

To investigate the effect of hydraulic retention time (HRT) and temperature (T) on bacterial community structure and volatile fatty acids (VFAs) production of an acidogenic process, and VFA production and changes in the bacterial community in three identical automated anaerobic continuously-stirred tank reactors were analyzed using response surface analysis (RSA) and nonmetric multidimensional scaling (NMDS). For RSA, 11 trials were conducted to find the combination of T and HRT under which VFA production was greatest; VFA production was affected more by HRT than by T. To identify the bacterial community structure in each trial, DNA from each experimental point of the RSA was analyzed using denaturating gradient gel electrophoresis (DGGE), and eight bacteria species were detected.

Acclimation and activity of ammonia-oxidizing bacteria with respect to variations in zinc concentration, temperature, and microbial population.

Activity of ammonia-oxidizing bacteria (AOB) to simultaneous variation in Zn(2+) concentration (0.01-3.5mg/L), temperature (23-33°C), and AOB concentration (3-30 × 10(6)gene copies/mL) in a steel industry wastewater treatment plant was evaluated.

A comprehensive microbial insight into two-stage anaerobic digestion of food waste-recycling wastewater.

Microbial community structures were assessed in a two-stage anaerobic digestion system treating food waste-recycling wastewater. The reactors were operated for 390 d at 10 different hydraulic retention times (HRTs) ranging from 25 to 4 d. Stable operation was achieved with the overall chemical oxygen demand (COD) removal efficiency of 73.

Simultaneous effect of temperature, cyanide and ammonia-oxidizing bacteria concentrations on ammonia oxidation.

For biological nitrification, a set of experiments were carried out to approximate the response of lag period along with ammonia oxidation rate with respect to different concentrations of cyanide (CN-) and ammonia-oxidizing bacteria (AOB), and temperature variation in laboratory-scale batch reactors. The effects of simultaneous changes in these three factors on ammonia oxidation were quantitatively estimated and modeled using response surface analysis. The lag period and the ammonia oxidation rate responded differently to changes in the three factors.

Use of quantitative real-time PCR to monitor population dynamics of ammonia-oxidizing bacteria in batch process.

A quantitative real-time PCR (QPCR) assay with the TaqMan system was used to quantify 16S rRNA genes of beta-proteobacterial ammonia-oxidizing bacteria (AOB) in a batch nitrification bioreactor. Five different sets of primers, together with a TaqMan probe, were used to quantify the 16S rRNA genes of beta-proteobacterial AOB belonging to the Nitrosomonas europaea, Nitrosococcus mobilis, Nitrosomonas nitrosa, and Nitrosomonas cryotolerans clusters, and the genus Nitrosospira. We also used PCR followed by denaturing gradient gel electrophoresis (DGGE), cloning, and sequencing of their 16S rRNA genes to identify the AOB species.

Biochemical indication of microbial mass changes using ATP and DNA measurement in biological treatment of thiocyanate.

This study was designed to monitor changes in the levels of adenosine 5'-triphosphate (ATP) and deoxyribonucleic acid (DNA) per unit of microbial mass during the autotrophic biodegradation of thiocyanate (SCN(-)). An artificial medium containing trace minerals and 500 mg SCN(-)/L was used as a substrate for bacterial growth. An SCN(-)-degrading bioreactor with a working volume of 6 L, equipped with temperature, pH, and dissolved oxygen controls, was operated in batch mode.

Primer and probe sets for group-specific quantification of the genera Nitrosomonas and Nitrosospira using real-time PCR.

Use of quantitative real-time PCR (QPCR) with TaqMan probes is increasingly popular in various environmental works to detect and quantify a specific microorganism or a group of target microorganism. Although many aspects of conducting a QPCR assay have become very easy to perform, a proper design of oligonucleotide sequences comprising primers and a probe is still considered as one of the most important aspects of a QPCR application. This work was conducted to design group specific primer and probe sets for the detection of ammonia oxidizing bacteria (AOB) using a real-time PCR with a TaqMan system.

Biokinetic evaluation and modeling of continuous thiocyanate biodegradation by Klebsiella sp.

Biokinetics for autotrophic degradation of thiocyanate using batch culture of Klebsiella sp. were evaluated both analytically and numerically. A sequential approach with an analytical method followed by a numerical approximation was used to evaluate and to ensure the accuracy of the parameter estimation.