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Bauxite residue is an industrial waste generated from the alumina refining industry, raising great concerns about environmental pollution. The primary problem for bauxite residue is its high alkalinity and salinity. This beneficial reuse of bauxite residue is desirable for the sustainable management of this waste stream. Bauxite residues can be used as an option of flue gas desulfurization to reduce the toxicity associated with high alkalinity. In this dissertation, it was first identified the linkage between the characteristics of the bauxite residues and their acid neutralization capacity (ANC). Further options of beneficial use were investigated according to the characteristics of bauxite residues. With the iron oxide-rich mineralogy, bauxite residue exhibited excellent capabilities to remove aqueous phosphate at environmentally relevant concentrations. Given that phosphate is an important nutrient, the removal and concentration of phosphorus with bauxite residue could be a strategy for the recovery of phosphorus as a resource. With its cation exchange capacity, bauxite residues were also found to be able to remove ciprofloxacin as an extensively used antibiotic and potential water pollutant. These findings show that bauxite residues could be used as feasible sorbents for pollution mitigation as well as resource recovery. The beneficial use was further demonstrated in the utilization of bauxite residues as an additive in anaerobic digestion, which is frequently implemented for the stabilization of organic waste and the production of biogas as a renewable energy source. My work shows that bauxite residues could be readily neutralized by the buffering capacity of the digestate in the anaerobic digestion without negatively impacting process performance. More importantly, the addition of bauxite residue could enhance the availability of phosphorus in the digestate which is desirable for the land application of anaerobic digestate as a soil supplement. In summary, this work has developed multiple pathways for the sustainable management of bauxite residue as a hazardous material with integrated applications in pollution mitigation and resource recovery.

Loline alkaloids (LA) are secondary metabolites produced by Epichloandamp;euml; (anamorph, Neotyphodium) grass endophytes. They are toxic and deterrent to a broad range of herbivorous insects but not to livestock. This protective bioactivity has spurred considerable research into the LA biosynthetic pathway. LOL, the gene cluster containing nine genes, is required for LA biosynthesis. The regulation of LOL genes during LA production in culture and in symbio is of interest. In this study, coordinate regulation between LOL gene expression and LA production level was investigated in both MM culture and symbiota. Results showed that expression of LOL genes in N. uncinatum MM culture were tightly correlated with each other (p andamp;lt; 0.0005), and all presented a significant temporal quadratic pattern during LA production. Gene expression started before LA were detectable, and increased while LA accumulated. The highest gene expression level was reached before the highest amounts of LA were detected, and gene expression level declined to a very low level after amounts of LA plateaued. Observations suggested that the hierarchical clusters based on the correlation coefficient could help to predict the roles of LOL genes in the LA pathway. In symbiota, coordinate coregulation of LOL gene expression with LA was found in E. festucae-meadow fescue inflorescences and stromata, whereby lower LOL gene expression corresponded with the lower LA level in stromata. In N. uncinatum (or N. siegelii)-meadow fescue vegetative tissues, dramatically higher LA levels were found in younger leaf tissue than in older leaf tissue, yet no evidence was found to relate this difference to LOL gene expression differences. Instead, substrate availability may regulate the LA level. In particular, asparagine was more than 10-fold higher in young leaf tissue than in old tissue, although proline was significantly lower in young tissue. Therefore, different regulatory mechanisms underlie LOL gene expression and LA production in different circumstances. The GUS activity of Pro-lolC2-GUS and Pro-lolA2-GUS in Neotyphodium species was almost undetectable in culture, though the activity could be detected in symbiota. The mRNA of GUS did not exhibit the same pattern as lolC2 or lolA2 in culture during LA production time course. A Pro-lolC2-cre transgene was expressed in complex medium, in which lolC2 mRNA was not detectable. These results suggest that proper regulation of LOL genes in culture or symbiota is dependent on the LOL cluster.