Evolution of pollutant biodegradation.

Pollutant-derived risks to human and environmental health are exacerbated by slow natural attenuation rates, often driven by pollutant toxicity to microorganisms that can degrade them or limitations to the ability of microorganisms to metabolise them. This review explores mechanisms employed by bacteria to protect themselves from pollutant toxicity in the context of the evolution of pollutant-degrading abilities. The role of promiscuous enzymes in pollutant transformation is subsequently reviewed, highlighting the emergence of novel metabolic pathways and their transcriptional regulation in response to pollutant exposure, followed by the gene transcription regulation to optimise the cellular component synthesis for adaptation on the novel substrate.

Aeration promotes Proteobacteria over Firmicutes in macerated food waste, resulting in superior anaerobic digestion efficiency.

Aeration is a common pretreatment method to enhance biogas production via anaerobic digestion of waste organic feedstocks such as unused food. While impacts on downstream anaerobic digestion have been intensively investigated, the consequence of aeration on the microbial community in food waste has not been characterized. Food waste has a low pH resulting from the dominance of lactic acid bacteria within the Firmicutes phylum.

Wastewater treatment bacteria show differential preference for colonizing natural biopolymers.

Most reduced organic matter entering activated sludge systems is particulate (1-100-µm diameter) or colloidal (0.001-1-µm diameter), yet little is known about colonization of particulate organic matter by activated sludge bacteria. In this study, colonization of biopolymers (chitin, keratin, lignocellulose, lignin, and cellulose) by activated sludge bacteria was compared with colonization of glass beads in the presence and absence of regular nutrient amendment (acetate and ammonia).

Ascorbic acid modulates the structure of the virulence factor pyocyanin and ascorbic acid-furanone-30 combination facilitate biofilm disruption.

The production of pyocyanin by increases its virulence, fitness and biofilm formation. Pyocyanin is also a redox molecule and we hypothesize that ascorbic acid being an antioxidant will interact with pyocyanin. The main objective of this study was to investigate the potential interaction of ascorbic acid with pyocyanin, and also to investigate the impact of ascorbic acid in combination with Furanone-30 on quorum sensing and biofilm formation of .

Constraining source attribution of methane in an alluvial aquifer with multiple recharge pathways.

Identifying the source of methane (CH) in groundwater is often complicated due to various production, degradation and migration pathways, particularly in settings where there are multiple groundwater recharge pathways. This study demonstrates the ability to constrain the origin of CH within an alluvial aquifer that could be sourced from in situ microbiological production or underlying formations at depth. To characterise the hydrochemical and microbiological processes active within the alluvium, previously reported hydrochemical data (major ion chemistry and isotopic tracers (H, C, Cl)) were interpreted in the context of CH and carbon dioxide (CO) isotopic chemistry, and the microbial community composition in the groundwater.

Isolation, characterization and bioaugmentation of an acidotolerant 1,2-dichloroethane respiring Desulfitobacterium species from a low pH aquifer.

A Desulfitobacterium sp. strain AusDCA of the Peptococcaceae family capable of respiring 1,2-dichloroethane (1,2-DCA) to ethene anaerobically with ethanol or hydrogen as electron donor at pH 5.0 with optimal range between pH 6.

Dependency of DNA extraction efficiency on cell concentration confounds molecular quantification of microorganisms in groundwater.

Quantification of microbes in water systems is essential to industrial practices ranging from drinking water and wastewater treatment to groundwater remediation. While quantification using DNA-based molecular methods is precise, the accuracy is dependent on DNA extraction efficiencies. We show that the DNA yield is strongly impacted by the cell concentration in groundwater samples (r = -0.

Heterologous Production and Purification of a Functional Chloroform Reductive Dehalogenase.

Reductive dehalogenases (RDases) are key enzymes involved in the respiratory process of anaerobic organohalide respiring bacteria (ORB). Heterologous expression of respiratory RDases is desirable for structural and functional studies; however, there are few reports of successful expression of these enzymes. Dehalobacter sp.

Glutathione Enhances Antibiotic Efficiency and Effectiveness of DNase I in Disrupting Biofilms While Also Inhibiting Pyocyanin Activity, Thus Facilitating Restoration of Cell Enzymatic Activity, Confluence and Viability.

Pyocyanin secreted by is a virulence factor that damages epithelial cells during infection through the action of reactive oxygen species, however, little is known about its direct effect on biofilms. We demonstrated that pyocyanin-producing strains (PA14WT, DKN370, AES-1R, and AES-2) formed robust biofilms in contrast to the poorly formed biofilms of the pyocyanin mutant PA14Δ and the low pyocyanin producer AES-1M. Addition of DNase I and reduced glutathione (GSH) significantly reduced biofilm biomass of pyocyanin-producing strains ( < 0.

Design and synthesis of short amphiphilic cationic peptidomimetics based on biphenyl backbone as antibacterial agents.

Antimicrobial peptides (AMPs) and their synthetic mimics have received recent interest as new alternatives to traditional antibiotics in attempts to overcome the rise of antibiotic resistance in many microbes. AMPs are part of the natural defenses of most living organisms and they also have a unique mechanism of action against bacteria. Herein, a new series of short amphiphilic cationic peptidomimetics were synthesized by incorporating the 3'-amino-[1,1'-biphenyl]-3-carboxylic acid backbone to mimic the essential properties of natural AMPs.

Co-occurrence of genes for aerobic and anaerobic biodegradation of dichloroethane in organochlorine-contaminated groundwater.

1,2-Dichloroethane (DCA) is a problematic groundwater pollutant. Factors influencing the distribution and activities of DCA-degrading bacteria are not well understood, which has hampered their application for bioremediation. Here, we used quantitative PCR to investigate the distribution of putative DCA-dehalogenating bacteria at a DCA-impacted site in Sydney (Australia).

Nutrient and acetate amendment leads to acetoclastic methane production and microbial community change in a non-producing Australian coal well.

Coal mining is responsible for 11% of total anthropogenic methane emission thereby contributing considerably to climate change. Attempts to harvest coalbed methane for energy production are challenged by relatively low methane concentrations. In this study, we investigated whether nutrient and acetate amendment of a non-producing sub-bituminous coal well could transform the system to a methane source.

Synthesis and biological evaluation of novel acyclic and cyclic glyoxamide based derivatives as bacterial quorum sensing and biofilm inhibitors.

Bacteria regulate the expression of various virulence factors and processes such as biofilm formation through a chemically-mediated communication mechanism called quorum sensing. Bacterial biofilms contribute to antimicrobial resistance as they can protect bacteria embedded in their matrix from the effects of antibiotics. Thus, developing novel quorum sensing inhibitors, which can inhibit biofilm formation, is a viable strategy to combat antimicrobial resistance.

A bacterial chloroform reductive dehalogenase: purification and biochemical characterization.

We report herein the purification of a chloroform (CF)-reducing enzyme, TmrA, from the membrane fraction of a strict anaerobe Dehalobacter sp. strain UNSWDHB to apparent homogeneity with an approximate 23-fold increase in relative purity compared to crude lysate. The membrane fraction obtained by ultracentrifugation was solubilized in Triton X-100 in the presence of glycerol, followed by purification by anion exchange chromatography.

Isolation and Characterization of sp. Strain TeCB1 Including Identification of TcbA: A Novel Tetra- and Trichlorobenzene Reductive Dehalogenase.

sp. strain TeCB1 was isolated from groundwater near Sydney, Australia, that is polluted with a range of organochlorines. The isolated strain is able to grow by reductive dechlorination of 1,2,4,5-tetrachlorobenzene to 1,3- and 1,4-dichlorobenzene with 1,2,4-trichlorobenzene being the intermediate daughter product.

Genome Sequence of sp. Strain TeCB1, Able To Respire Chlorinated Benzenes.

sp. strain TeCB1 was isolated from groundwater contaminated with a mixture of organohalides and is able to respire 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene. Here, we report its 3.

Amphipathic guanidine-embedded glyoxamide-based peptidomimetics as novel antibacterial agents and biofilm disruptors.

Antimicrobial resistance in bacteria is becoming increasingly prevalent, posing a critical challenge to global health. Bacterial biofilm formation is a common resistance mechanism that reduces the effectiveness of antibiotics. Thus, the development of compounds that can disrupt bacterial biofilms is a potential strategy to combat antimicrobial resistance.

Synthesis of antimicrobial glucosamides as bacterial quorum sensing mechanism inhibitors.

Bacteria communicate with one another and regulate their pathogenicity through a phenomenon known as quorum sensing (QS). When the bacterial colony reaches a threshold density, the QS system induces the production of virulence factors and the formation of biofilms, a powerful defence system against the host's immune responses. The glucosamine monomer has been shown to disrupt the bacterial QS system by inhibiting autoinducer (AI) signalling molecules such as the acyl-homoserine lactones (AHLs).

Investigation of the microbial communities colonizing prepainted steel used for roofing and walling.

Microbial colonization of prepainted steel, commonly used in roofing applications, impacts their aesthetics, durability, and functionality. Understanding the relevant organisms and the mechanisms by which colonization occurs would provide valuable information that can be subsequently used to design fouling prevention strategies. Here, next-generation sequencing and microbial community finger printing (T-RFLP) were used to study the community composition of microbes colonizing prepainted steel roofing materials at Burrawang, Australia and Kapar, Malaysia over a 52-week period.

N-Acetylglucosamine Inhibits LuxR, LasR and CviR Based Quorum Sensing Regulated Gene Expression Levels.

N-acetyl glucosamine, the monomer of chitin, is an abundant source of carbon and nitrogen in nature as it is the main component and breakdown product of many structural polymers. Some bacteria use N-acyl-L-homoserine lactone (AHL) mediated quorum sensing (QS) to regulate chitinase production in order to catalyze the cleavage of chitin polymers into water soluble N-acetyl-D-glucosamine (NAG) monomers. In this study, the impact of NAG on QS activities of LuxR, LasR, and CviR regulated gene expression was investigated by examining the effect of NAG on QS regulated green fluorescent protein (GFP), violacein and extracellular chitinase expression.

High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors.

A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate.

Serratia Secondary Metabolite Prodigiosin Inhibits Pseudomonas aeruginosa Biofilm Development by Producing Reactive Oxygen Species that Damage Biological Molecules.

Prodigiosin is a heterocyclic bacterial secondary metabolite belonging to the class of tripyrrole compounds, synthesized by various types of bacteria including Serratia species. Prodigiosin has been the subject of intense research over the last decade for its ability to induce apoptosis in several cancer cell lines. Reports suggest that prodigiosin promotes oxidative damage to double-stranded DNA (dsDNA) in the presence of copper ions and consequently leads to inhibition of cell-cycle progression and cell death.

Application of stable isotope tools for evaluating natural and stimulated biodegradation of organic pollutants in field studies.

Stable isotope tools are increasingly applied for in-depth evaluation of biodegradation of organic pollutants at contaminated field sites. They can be divided into three methods i) determination of changes in natural abundance of stable isotopes using compound-specific stable isotope analysis (CSIA), ii) detection of incorporation of stable-isotope label from a stable-isotope labelled target compound into degradation and/or mineralisation products and iii) determination of stable-isotope label incorporation into biomarkers using stable isotope probing (SIP). Stable isotope tools have been applied as key monitoring tools for multiple-line-of-evidence-approaches (MLEA) for sensitive evaluation of pollutant biodegradation.

RNA-stable isotope probing: from carbon flow within key microbiota to targeted transcriptomes.

Stable isotope probing of RNA has enthused researchers right from its first introduction in 2002. The concept of a labelling-based detection of process-targeted microbes independent of cellular replication or growth has allowed for a much more direct handle on functionally relevant microbiota than by labelling of other biomarkers. This has led to a widespread application of the technology, and breakthroughs in our understanding of carbon flow in natural microbiomes, autotrophic and heterotrophic physiologies, microbial food webs, host-microbe interactions and environmental biotechnology.