Anna Grandin

Arbuscular mycorrhiza improves yield and nutritional properties of onion (Allium cepa)

Improving the nutritional value of commonly cultivated crops is one of the most pending problems for modern agriculture. In natural environments plants associate with a multitude of fungal microorganisms that improve plant fitness. The best described group are arbuscular mycorrhizal fungi (AMF). These fungi have been previously shown to improve the quality and yield of several common crops. In this study we tested the potential utilization of Rhizophagus irregularis in accelerating growth and increasing the content of important dietary phytochemicals in onion (Allium cepa). Our results clearly indicate that biomass production, the abundance of vitamin B1 and its analogues and organic acid concentration can be improved by inoculating the plant with AM fungi. We have shown that improved growth is accompanied with up-regulated electron transport in PSII and antioxidant enzyme activity.

Bioleaching of Shale – Impact of Carbon Source

Bioleaching is often used for processing low-grade shale feedstock and the microbial community used for that purpose is supplied with nutrients such as sugar and/or Fe2+. In the present study, the leaching efficiency was tested when crushed weathered shale was mixed with aspen wood shavings and kept moist, at the mixtures field capacity. The purpose was to investigate whether a more complex carbon source and a lower content of water may be a feasible way of lowering the cost for bioleaching. After 56 days of incubation the amount of uranium mobilized from the shale reached some 1.7% with a minimum of effort and cost.

Uranium induced stress promotes fungal excretion of uranium/metal stabilizing ligands : Analysis of metal-organic compounds with Size Exclusion Chromatography and Inductively Coupled Plasma-Mass Spectroscopy

Weathering of pyrite rich alum shale processing waste has led to metal pollution in Kvarntorp, Sweden. Here we use a fungal strain isolated from the site to monitor the excretion of uranium/metal stabilizing ligands under uranium induced stress. After 2 weeks 91 % was lost from a 10 mg L−1 solution but 57 % already within 10 min. The formation of colloidal/particulate uranium is mainly controlled by organic exudates phosphorus excreted by the fungus. Most likely, the change in solution properties from metabolic processes resulted in the formation species through adsorption and precipitation.