The temporal stability and change of the dominant phylogenetic groups of the domain bacteria were studied in a model plant-based industrial wastewater treatment system showing high levels of organic carbon removal supported by high levels of N2 fixation. Community profiles were obtained through terminal restriction fragment length polymorphism analysis and cloning of 16S rRNA amplicons followed by sequencing. Bacterial community profiles showed that ten common terminal restriction fragments made up approximately 50% of the measured bacterial community. As much as 42% of the measured bacterial community could be monitored by using quantitative PCR and primers that targeted three dominant operational taxonomic units. Despite changes in wastewater composition and dissolved oxygen levels, the bacterial community composition appeared stable and was dominated by alpha-Proteobacteria and beta-Proteobacteria, with a lesser amount of the highly diverse bacterial phylum Bacteroidetes. A short period of considerable change in the bacterial community composition did not appear to affect treatment performance indicating functional redundancy in this treatment system.

Currently no one universal method exists for processing FTIR data for polyhydroxyalkanoates (PHA) quantification. This study compares three different methods of analysing FTIR data for quantification of PHAs in biomass. A new data-processing approach was proposed and the results were compared against existing literature methods. Most publications report PHA quantification of medium range in pure culture. However, in our study we encompassed both mixed and pure culture biomass containing a broader range of PHA in the calibration curve. The resulting prediction model is useful for rapid quantification of a wider range of PHA content in biomass.

High levels of nitrogen fixation have been observed in the wastewaters of pulp and paper mills. In this study, we show that nitrogen fixation in a model pulp and paper wastewater treatment system is supported by a high density of nifH sequences that are of low diversity. Quantitative PCR revealed a ratio of nifH to 16S rDNA of 1.14 +/- 0.76 which shows that very high levels of the nifH gene were enriched to support the high rates of nitrogen fixation that occur in this wastewater. Changes in wastewater composition and dissolved oxygen levels did not affect the nifH levels and allowed stable wastewater treatment. The nifH sequences identified display a similar profile to those seen in forest soil environments where nifH sequences derived from alpha-proteobacteria and beta-proteobacteria are also prevalent.

BACKGROUND: Forest biomass represents a potential low-cost feedstock for polyhydroxyalkanoate (PHA) production. Softwoods, such as Pinus radiata (D.Don) are difficult to digest and require special pretreatments to expose polysaccharides for enzymatic saccharification. Different pretreatments can lead to inhibitor formation that may adversely affect PHA synthesis. RESULTS:Pinus radiata wood chips were subjected to high-temperature mechanical pre-treatment (HTMP) or steam explosion in the presence of sulphur dioxide (SEW) before being enzymatically treated to produce corresponding hydrolysates. Two PHA-producing bacteria Novosphingobium nitrogenifigens Y88 T and Sphingobium scionense WP01 T were grown on these hydrolysates. The highest content of PHA was produced by WP01 grown on HTMP hydrolysate (32% w/w PHA, Y PHA/glucose = 0.22 and theoretical maximum yield of 46%). Gas chromatography and proton nuclear magnetic resonance spectroscopy indicated that the PHA produced was made up of polyhydroxybutyrate (PHB) with molecular weights ranging from 50-1600 kDa and polydispersities between 4.6 and 8.4. The melting temperature was close to that of pure PHB with percentage crystallinity ranging from 44-64%. CONCLUSION: This is the first report on the production of PHA from softwood hydrolysates derived from enzymatically saccharified pretreated Pinus radiata pulps. PHA characterizationPolymer composition analysed by GC showed that the PHA produced was exclusively made up of PHB, irrespective of microbial strain and carbon source. Proton NMR spectra of the isolated PHA polymer confirmed that different PHA samples are exclusively made up of PHB ≥ 95% w/w. A representative 1 H NMR spectrum of best case PHA produced from strain wileyonlinelibrary.com/jctb