Evaluation of membrane fouling in a microalgal-bacterial membrane photobioreactor: Effects of SRT.

As a novel system, the microalgal-bacterial membrane photobioreactor (MPBR) has better performance than the conventional MBRs in membrane fouling control. Nevertheless, how the operating conditions affect its fouling performance is rarely reported. In this study, a microalgal-bacterial MPBR was set and continuously operated to treat synthetic wastewater.

Membrane fouling in a microalgal-bacterial membrane photobioreactor: Effects of P-availability controlled by N:P ratio.

Microalgal-bacterial membrane photobioreactor (MB-MPBR) is a promising technology to simultaneously remove organics and nutrients from wastewater. However, membrane fouling in MB-MPBR was seldom studied. In this study, potential effects of P-availability on biomass properties and membrane fouling in MB-MPBR were investigated.

The biological performance of a novel microalgal-bacterial membrane photobioreactor: Effects of HRT and N/P ratio.

A microalgal-bacterial membrane photobioreactor (MB-MPBR) was developed for simultaneous COD and nutrients (N and P) removals from synthetic municipal wastewater in a single stage for a long-term operation over 350 days. The effects of hydraulic retention time (HRT) and N/P ratio on the biological performance were systematically evaluated for the first time. The results showed that a lower N/P ratio (3.

A unified thermodynamic mechanism underlying fouling behaviors of soluble microbial products (SMPs) in a membrane bioreactor.

Soluble microbial products (SMPs) are the predominate foulants determining fouling extent in membrane bioreactors (MBRs). However, exact mechanism underlying their typical fouling behaviors remains unrevealed. In this study, the typical fouling behaviors of SMPs during initial operational period of a MBR were characterized.

Role of rpoS in Escherichia coli O157:H7 strain H32 biofilm development and survival.

The protein RpoS is responsible for mediating cell survival during the stationary phase by conferring cell resistance to various stressors and has been linked to biofilm formation. In this study, the role of the rpoS gene in Escherichia coli O157:H7 biofilm formation and survival in water was investigated. Confocal scanning laser microscopy of biofilms established on coverslips revealed a nutrient-dependent role of rpoS in biofilm formation, where the biofilm biomass volume of the rpoS mutant was 2.

Increased expression of β-glucosidase A in Clostridium thermocellum 27405 significantly increases cellulase activity.

β-glucosidase A (bglA) in Clostridium thermocellum 27405 was increased by expression from shuttle vector pIBglA in attempts to increase cellulase activity and ethanol titer by lowering the end product inhibition of cellulase. Through a modified electrotransformation protocol C. thermocellum transformant (+MCbglA) harbouring pIBglA was produced.

Newly isolated and characterized bacteria with great application potential for decomposition of lignocellulosic biomass.

This study focuses on the isolation and characterization of bacteria from municipal waste and peat to determine those bacteria with good potential for modification and decomposition of lignocellulosic biomass for industrial application. Twenty cellulase-producing bacteria belonging to four major phyla - Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes - were found when screened on carboxymethyl cellulose-containing agar. Six isolates also exhibited activities towards filter paper as the sole carbon source in salt media, while 12 exhibited activities towards xylan when screened on xylan-containing plates.

Recent advances in membrane technologies for biorefining and bioenergy production.

The bioeconomy, and in particular, biorefining and bioenergy production, have received considerable attention in recent years as a shift to renewable bioresources to produce similar energy and chemicals derived from fossil energy sources, represents a more sustainable path. Membrane technologies have been shown to play a key role in process intensification and products recovery and purification in biorefining and bioenergy production processes. Among the various separation technologies used, membrane technologies provide excellent fractionation and separation capabilities, low chemical consumption, and reduced energy requirements.

Persistence of Escherichia coli in freshwater periphyton: biofilm-forming capacity as a selective advantage.

Recent research has shown that Escherichia coli can persist in aquatic environments, although the characteristics that contribute to their survival remain poorly understood. This study examines periphytic E. coli populations that were continuously present in three temperate freshwater lakes from June to October 2008 in numbers ranging from 2 to 2 × 10(2)  CFU 100 cm(-2) .

Characterization of some efficient cellulase producing bacteria isolated from paper mill sludges and organic fertilizers.

The wide variety of bacteria in the environment permits screening for more efficient cellulases to help overcome current challenges in biofuel production. This study focuses on the isolation of efficient cellulase producing bacteria found in organic fertilizers and paper mill sludges which can be considered for use in large scale biorefining. Pure isolate cultures were screened for cellulase activity.

Cellulase activities in biomass conversion: measurement methods and comparison.

Cellulose, the major constituent of all plant materials and the most abundant organic molecule on the Earth, is a linear biopolymer of glucose molecules, connected by β-1,4-glycosidic bonds. Enzymatic hydrolysis of cellulose requires mixtures of hydrolytic enzymes including endoglucanases, exoglucanases (cellobiohydrolases), and β-glucosidases acting in a synergistic manner. In biopolymer hydrolysis studies, enzyme assay is an indispensable part.

A novel selective growth medium-PCR assay to isolate and detect Sphingomonas in environmental samples.

Sphingomonas species can be found ubiquitously in the environment and can be frequently found in surface biofilms. Some Sphingomonas strains are well known for metabolizing complex organic pollutants but some are opportunistic human pathogens. Despite the importance of the Sphingomonas species, a reliable system to isolate this group of bacteria from the environment has not been developed.

The prospects of cellulase-producing bacteria for the bioconversion of lignocellulosic biomass.

Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. However, the biorefining process remains economically unfeasible due to a lack of biocatalysts that can overcome costly hurdles such as cooling from high temperature, pumping of oxygen/stirring, and, neutralization from acidic or basic pH. The extreme environmental resistance of bacteria permits screening and isolation of novel cellulases to help overcome these challenges.

Chromosomal gfp labelling of Pseudomonas aeruginosa using a mini-Tn7 transposon: application for studies of bacteria-host interactions.

Analysis of bacterial interactions with host cells using multiple techniques is essential for studies on microbial pathogenesis and for the development of new antimicrobial therapies. Pseudomonas aeruginosa is an important opportunistic pathogen that can cause severe, often life-threatening pulmonary infections in individuals with impaired host defense mechanisms. Using a mini-Tn7 transposon delivery system, we have chromosomally labelled the strain P.

The bactericidal effect of ultraviolet and visible light on Escherichia coli.

The bactericidal radiation dosages at specific wavelengths in the ultraviolet (UV)-visible spectrum are not well documented. Such information is important for the development of new monochromatic bactericidal devices to be operated at different wavelengths. In this study, radiation dosages required to cause mortality of an Escherichia coli strain, ATCC 25922, at various wavelengths between 250 and 532 nm in the UV and visible spectrum were determined.

Effect of carbon starvation on p-nitrophenol degradation by a Moraxella strain in buffer and river water.

This study examines the effect of carbon starvation on the ability of a Moraxella sp. strain to degrade p-nitrophenol (PNP). Carbon starvation for 24 h decreased the induction time for p-nitrophenol degradation by the bacterium in a minimal salt medium from 6 to 1 h but it did not completely eliminate the induction time.

Stress-survival responses of a carbon-starved p-nitrophenol-mineralizing Moraxella strain in river water.

The effect of carbon starvation on the stress-resistant responses of a p-nitrophenol-mineralizing Moraxella strain was examined in both buffer and river water samples. The Moraxella strain showed optimal stress-resistant responses in a minimal salt buffer when carbon-starved for 1-2 d. In the buffer system, the 1- and 2-day carbon-starved Moraxella cultures survived about 150-, 200-, and 100-fold better than the non-starved cultures when exposed to 43.

Multiplex PCR-DNA probe assay for the detection of pathogenic Escherichia coli.

A multiplex PCR-DNA probing assay was developed to detect four major Escherichia coli virotypes. Six highly specific polymerase chain reaction (PCR) primer sets and DIG-labeled chemiluminescent probes were designed to target the Shiga-like toxin I and II genes (stxI and stxII) of verotoxigenic E. coli (VTEC), heat-stable and heat-labile toxin genes of enterotoxigenic E.

A comparison of AFLP and ERIC-PCR analyses for discriminating Escherichia coli from cattle, pig and human sources.

Amplified fragment length polymorphism (AFLP) and enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) genomic fingerprinting assays were compared for their ability to differentiate Escherichia coli isolates obtained from various host sources, and with respect to their pathogenicity. One hundred and ten verotoxigenic, enterotoxigenic and non-pathogenic E. coli isolates obtained from cattle, humans and pigs were used in this study.

A comparison of DNA extraction and purification methods to detect Escherichia coli O157:H7 in cattle manure.

The extraction of DNA from manure and the subsequent polymerase chain reaction (PCR) amplification of virulence genes to detect pathogens require an effective method of purification. Four different methods were assessed for their effectiveness in extracting and purifying Escherichia coli O157:H7 DNA from cattle manure: phenol/chloroform purification, phenol/chloroform/Sepharose B4 spin columns, phenol/chloroform/polyvinylpolypyrrolidone (PVPP) spun columns, and Mo Bio UltraClean kit. A PCR assay targeting the shiga-like toxin I gene (sltI) was carried out to determine the effectiveness of the four methods in removing PCR inhibitors from the manure samples.