Biomethane potential of industrial paper wastes and investigation of the methanogenic communities involved.

Background: Cellulose-containing waste products from the agricultural or industrial sector are potentially one of the largest sources of renewable energy on earth. In this study, the biomethane potential (BMP) of two types of industrial paper wastes, wood and pulp residues (WR and PR, respectively), were evaluated under both mesophilic and thermophilic conditions, and various pretreatment methods were applied in the attempt to increase the methane potential during anaerobic digestion. The methanogenic community composition was investigated with denaturing gradient gel electrophoresis (DGGE) and the ANAEROCHIP microarray, and dominant methanogens were quantitated using quantitative PCR.

Co-composting of biowaste and wood ash, influence on a microbially driven-process.

A trial at semi-industrial scale was conducted to evaluate the effect of wood ash amendment on communal biowaste in a composting process and on the final composts produced. For this purpose, three treatments including an unamended control (C0) and composts with additions of 6% (C6), and 12% (C12) of wood ash (w/w) were studied, and physico-chemical parameters as well as microbial activity and community composition were investigated. At the end of the process, composts were tested for toxicity and quality, and microbial physiological activity.

Methane yields and methanogenic community changes during co-fermentation of cattle slurry with empty fruit bunches of oil palm.

The biomethane potential and structural changes of the methanogenic community in a solid-state anaerobic digestion process co-digesting cattle slurry and empty fruit bunches were investigated under mesophilic (37°C) and thermophilic (55°C) conditions. Phylogenetic microarrays revealed the presence of two hydrogenotrophic genera (Methanoculleus and Methanobrevibacter) and one acetoclastic genus (Methanosarcina). Methanosarcina numbers were found to increase in both mesophilic and thermophilic treatments of empty fruit bunches.

Investigation into the effect of high concentrations of volatile fatty acids in anaerobic digestion on methanogenic communities.

A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP.

Changes in the microbial communities during co-composting of digestates.

Anaerobic digestion is a waste treatment method which is of increasing interest worldwide. At the end of the process, a digestate remains, which can gain added value by being composted. A study was conducted in order to investigate microbial community dynamics during the composting process of a mixture of anaerobic digestate (derived from the anaerobic digestion of municipal food waste), green wastes and a screened compost (green waste/kitchen waste compost), using the COMPOCHIP microarray.

Coffee husk composting: an investigation of the process using molecular and non-molecular tools.

Various parameters were measured during a 90-day composting process of coffee husk with cow dung (Pile 1), with fruit/vegetable wastes (Pile 2) and coffee husk alone (Pile 3). Samples were collected on days 0, 32 and 90 for chemical and microbiological analyses. C/N ratios of Piles 1 and 2 decreased significantly over the 90 days.

Biotic and abiotic processes contribute to successful anaerobic degradation of cyanide by UASB reactor biomass treating brewery waste water.

In contrast to the general aerobic detoxification of industrial effluents containing cyanide, anaerobic cyanide degradation is not well understood, including the microbial communities involved. To address this knowledge gap, this study measured anaerobic cyanide degradation and the rearrangements in bacterial and archaeal microbial communities in an upflow anaerobic sludge blanket (UASB) reactor biomass treating brewery waste water using bio-methane potential assays, molecular profiling, sequencing and microarray approaches. Successful biogas formation and cyanide removal without inhibition were observed at cyanide concentrations up to 5 mg l(-1).

Effects of pH and microbial composition on odour in food waste composting.

A major problem for composting plants is odour emission. Slow decomposition during prolonged low-pH conditions is a frequent process problem in food waste composting. The aim was to investigate correlations between low pH, odour and microbial composition during food waste composting.

Searching for links in the biotic characteristics and abiotic parameters of nine different biogas plants.

To find links between the biotic characteristics and abiotic process parameters in anaerobic digestion systems, the microbial communities of nine full-scale biogas plants in South Tyrol (Italy) and Vorarlberg (Austria) were investigated using molecular techniques and the physical and chemical properties were monitored. DNA from sludge samples was subjected to microarray hybridization with the ANAEROCHIP microarray and results indicated that sludge samples grouped into two main clusters, dominated either by Methanosarcina or by Methanosaeta, both aceticlastic methanogens. Hydrogenotrophic methanogens were hardly detected or if detected, gave low hybridization signals.

Treatment alternatives of slaughterhouse wastes, and their effect on the inactivation of different pathogens: a review.

Slaughterhouse wastes are a potential reservoir of bacterial, viral, prion and parasitic pathogens, capable of infecting both animals and humans. A quick, cost effective and safe disposal method is thus essential in order to reduce the risk of disease following animal slaughter. Different methods for the disposal of such wastes exist, including composting, anaerobic digestion (AD), alkaline hydrolysis (AH), rendering, incineration and burning.

Characterisation of source-separated household waste intended for composting.

Large-scale composting of source-separated household waste has expanded in recent years in the Nordic countries. One problem can be low pH at the start of the process. Incoming biowaste at four composting plants was characterised chemically, physically and microbiologically.

Design and development of the ANAEROCHIP microarray for investigation of methanogenic communities.

The aim of this study was to design a microarray targeting methanogens found in anaerobic digesters, and to apply this chip together with a cloning approach to investigate the methanogenic community present in an anaerobic digester. Oligonucleotide probes were designed based on sequence differences in the 16S rRNA genes in order to target microorganisms in situ. For microarray hybridisations, DNA was subjected to PCR amplification of the 16S rRNA gene and Cy5-labeled.

Population dynamics at digester overload conditions.

Two different case studies concerning potential overload situations of anaerobic digesters were investigated and mathematically modelled by means of the Anaerobic Digestion Model No. 1 (ADM1). The first scenario included a digester failure at a municipal WWTP which occurred during revision works of the upstream digester within a two-step digestion system when the sludge was directly by-passed to the 2nd-step reactor.

Design and testing of real-time PCR primers for the quantification of Methanoculleus, Methanosarcina, Methanothermobacter, and a group of uncultured methanogens.

In this study, 16S rRNA gene primers were designed to complement the suite of already available PCR primers for the detection of different methanogens involved in biogas production through anaerobic digestion by SYBR Green real-time PCR. Primers designed for use in TaqMan real-time PCR for the organisms Methanosaeta, Methanosarcina, and Methanoculleus have been described previously; however, we found that (i) the Methanoculleus primers were not specific to members of the genus and that (ii) the Methanosarcina primers did not work specifically with SYBR Green real-time PCR. Thus, we designed new primers for these and other methanogens, and we optimized SYBR Green real-time PCR assays.

Plant and animal wastes composting: effects of the N source on process performance.

The aim of this work was to evaluate the impact of different N-rich animal wastes on the composting of ligno-cellulosic wastes by a range of classical and novel methods, with particular emphasis on microbial community composition. Two composting mixtures were prepared by adding to a mixture of cotton carding wastes and wheat straw: (i) meat and bone meal and (ii) blood meal and horn and hoof meal. Composts were analyzed using physico-chemical and biochemical properties, as well as nucleic acid microarrays.

Application of COMPOCHIP microarray to investigate the bacterial communities of different composts.

A microarray spotted with 369 different 16S rRNA gene probes specific to microorganisms involved in the degradation process of organic waste during composting was developed. The microarray was tested with pure cultures, and of the 30,258 individual probe-target hybridization reactions performed, there were only 188 false positive (0.62%) and 22 false negative signals (0.

Molecular analysis of bacterial community succession during prolonged compost curing.

The compost environment consists of complex organic materials that form a habitat for a rich and diverse microbial community. The aim of this research was to study the dynamics of microbial communities during the compost-curing phase. Three different methods based on 16S rRNA gene sequence were applied to monitor changes in the microbial communities: (1) denaturing gradient gel electrophoresis of PCR-generated rRNA gene fragments; (2) partial rRNA gene clone libraries; and (3) a microarray of oligonucleotide probes targeting rRNA gene sequences.

Identification of anammox bacteria in a full-scale deammonification plant making use of anaerobic ammonia oxidation.

The existence of anaerobic ammonia-oxidizing (anammox) bacteria was postulated in the late 1970s. Approximately 20 years later, these lithotrophic members of the nitrogen cycle were identified as deep-branching members of the planctomycetes. Recently, full-scale implementation of biological deammonification was successfully achieved in the DEMON reactor at the wastewater treatment plant in Strass, Austria.

Microbial community related to volatile organic compound (VOC) emission in household biowaste.

Malodorous emissions and potentially pathogenic microorganisms which develop during domestic organic waste collection are not only a nuisance but may also pose health risks. The aim of the present study was to determine whether the presence of specific microorganisms in biowastes is directly related to the composition of the emitted volatile organic compounds (VOCs). The succession of microbial communities during 16 days of storage in organic waste collection bins was studied by denaturing gradient gel electrophoresis (DGGE) of amplified 16S ribosomal DNA in parallel with a classical cultivation and isolation approach.

Design, development, and use of molecular primers and probes for the detection of Gluconacetobacter species in the pink sugarcane mealybug.

Molecular tools for the species-specific detection of Gluconacetobacter sacchari, Gluconacetobacter diazotrophicus, and Gluconacetobacter liquefaciens from the pink sugarcane mealybug (PSMB) Saccharicoccus sacchari Cockerell (Homiptera: Pseudococcidae) were developed and used in polymerase chain reactions (PCR) and in fluorescence in situ hybridizations (FISH) to better understand the microbial diversity and the numerical significance of the acetic acid bacteria in the PSMB microenvironment. The presence of these species in the PSMB occurred over a wide range of sites, but not in all sites in sugarcane-growing areas of Queensland, Australia, and was variable over time. Molecular probes for use in FISH were also designed for the three acetic acid bacterial species, and shown to be specific only for the target species.

Comparison of different labeling methods for the production of labeled target DNA for microarray hybridization.

Different labeling methods were studied to compare various approaches to the preparation of labeled target DNA for microarray experiments. The methods under investigation included a post-PCR labeling method using the Klenow fragment and a DecaLabel DNA labeling kit, the use of a Cy3-labeled forward primer in the PCR, generating either double-stranded or single-stranded PCR products, and the incorporation of Cy3-labeled dCTPs in the PCR. A microarray that had already been designed and used for the detection of microorganisms in compost was used in the study.

Design and application of an oligonucleotide microarray for the investigation of compost microbial communities.

A microarray consisting of oligonucleotide probes targeting variable regions of the 16S rRNA gene was designed and tested for the investigation of microbial communities in compost. Probes were designed for microorganisms that have been previously reported in the composting process and for plant, animal and human pathogens. The oligonucleotide probes were between 17 and 25 bp in length and included mostly species-specific sequences.