Knowledge of soil biology to reduce nitrogen loss as N2O from sugarcane farming

Contemporary cropping systems have to combine high yields with environmental sustainability. The conversion of nitrogen (N) fertiliser to forms which are easily lost from soil (as nitrate or gaseous N compounds) is driven by soil biology, specifically the soil microbial community. Although knowledge of soil microbial activity is crucial for minimising N loss, it is not known how soil conditions and associated microbes can best be manipulated through farming practices. We have developed new tools for fingerprinting microbial activities in soil. Our new method quantifies, for the first time, the activities of microbial genes that are switched on or off under certain conditions in the soil. The method links soil parameters and microbial activities by using a new custom-made microarray. The advantage of this novel mRNA-based approach is that it (i) measures of the ‘microbial activity’ rather than the ‘presence’ of specific microbes, (ii) monitors ‘activities’ of many microbial groups simultaneously, (iii) provides insights into whole-system soil biology. We have applied this technique to monitor microbial activities in cane soils with different management histories. Our preliminary results indicate that the method can successfully detect differences in the microbial activities of soils with different fertiliser application and N2O emission rates (Mackay), and different cropping history (Ingham). Ultimately this research will provide information for farmers to effectively manipulate soil biology to reduce N loss and improve productivity

Transcriptome for photobiological hydrogen production induced by sulfur deprivation in the green alga Chlamydomonas reinhardtii

Photobiological hydrogen production using microalgae is being developed into a promising clean fuel stream for the future. In this study, microarray analyses were used to obtain global expression profiles of mRNA abundance in the green alga Chlamydomonas reinhardtii at different time points before the onset and during the course of sulfur-depleted hydrogen production. These studies were followed by real-time quantitative reverse transcription-PCR and protein analyses. The present work provides new insights into photosynthesis, sulfur acquisition strategies, and carbon metabolism-related gene expression during sulfur-induced hydrogen production. A general trend toward repression of transcripts encoding photosynthetic genes was observed. In contrast to all other LHCBM genes, the abundance of the LHCBM9 transcript ( encoding a major light-harvesting polypeptide) and its protein was strongly elevated throughout the experiment. This suggests a major remodeling of the photosystem II light-harvesting complex as well as an important function of LHCBM9 under sulfur starvation and photobiological hydrogen production. This paper presents the first global transcriptional analysis of C. reinhardtii before, during, and after photobiological hydrogen production under sulfur deprivation

Transcriptional profiling of photosynthetic genes during photo-biological hydrogen production in the green alga Chlamydomonas reinhardtii

Photo-biological hydrogen production from water using microalgae is developing into a promising clean fuel stream for the future. In this study, microarray analyses were used to obtain global expression profiles of mRNA abundance in the green alga Chlamydomonas reinhardtii at different time points before the onset and during the course of sulphur-depleted hydrogen production. These studies were followed by real-time quantitative RT-PCR and protein analyses. The present work provides new insights into photosynthesis, sulphur acquisition strategies and carbon metabolism under sulphur starvation towards hydrogen production and confirms previous findings on the impacts of sulphur deprivation. For instance, while a general trend towards repression of transcripts encoding photosynthetic genes was observed, the abundance of the LHCBM9 transcript (encoding a major light harvesting polypeptide) and its protein was strongly elevated throughout the experiment while all other LHCBM genes were downregulated. This suggests a major remodelling of the photosystem II light harvesting complex as well as an important function of LHCBM9 under sulphur starvation and photo-biological hydrogen production. This study presents the first global transcriptional analysis of C. reinhardtii before, during and after photo-biological hydrogen production (PBHP)