Trichotreat

The development of alternative energy technologies is of utmost importance due to rising energy consumption and prices, depletion of fossil fuels, and growing emphasis in mitigating environmental impacts. In this regard, bioconversion of lignocellulosic biomass via anaerobic digestion has long been recognized as a desirable endeavor, since biomass represents an inexhaustible, ubiquitous natural resource. However, the highly heterogeneous structure and inherent recalcitrant nature of lignocellulosic biomass restricts the exploitation of its promising potential in biogas plants. Thus, effective pretreatment methods are decisive prerequisites to overcome these challenges in order to improve the utilization ratio of lignocellulosic substrates during fermentation. In the course of previous investigations the general potential and the conditions for a successful pre-treatment of bio-waste using the fungus Trichoderma viride were already defined. The procedure adopted offers a high potential for the comprehensive utilization of lignocellulosic (bio- waste)substrates for subsequent anaerobic digestion. During previous investigations an increase of several 100% in biogas and methane yield could be achieved. The pre-treatment procedure using T. viride in an aerobic step prior to anaerobic digestion represents an environmentally beneficial as well as cost- and energy-efficient technique to improve the efficiency of anaerobic digestion plants. Although the pre-treatment had a significantly beneficial effect, causes and mechanisms underlying the increased biogas yield are still awaiting elucidation. Therefore, the overall aim of the project is the systematic biochemical and microbiological investigation of the already developed biological, aerobic pre-treatment process using T. viride for subsequent anaerobic digestion. In detail the aims of the project comprise: to investigate the behavior of T. viride during the aerobic pre-treatment. to investigate T. viride induced changes during the aerobic pre-treatment, and to understand the impact on the downstream anaerobic digestion process. to investigate the engaged microbial consortia during aerobic pre-treatment and downstream anaerobic digestion. Concerning the methodology, a mixture of already well established chemical-analytical methods like HPLC, GC, etc., classical cultivation based methods as well as highly modern molecular biological methods such as next generations sequencing for microbiome profiling and gene expression profiling will be applied. The present project will provide the basis to understand the auspicious biological pre-treatment strategy using T. viride. With the knowledge of an understood pre-treatment process, a future middle and large scale application of the technology should become possible.

FWF project Trichotreat The development of alternative energy technologies is of utmost importance due to rising energy consumption and prices, depletion of fossil fuels, and growing emphasis in mitigating environmental impacts. In this regard, bioconversion of lignocellulosic biomass via anaerobic digestion has long been recognized as a desirable endeavor, since biomass represents an inexhaustible, ubiquitous natural resource. However, the highly heterogeneous structure and inherent recalcitrant nature of lignocellulosic biomass restricts the exploitation of its promising potential in biogas plants. Thus, effective pretreatment methods are decisive prerequisites to overcome these challenges in order to improve the utilization ratio of lignocellulosic substrates during fermentation. However, the progressively improved exploitation of organic substrates for biogas production increased both, methane yields and the risk of undesired by-product formation. Therefore, a deeper knowledge on the mode of action of a pre-treatment strategy and the impact on the subsequent anaerobic digestion process is of eminent importance. In the course of previous investigations, the potential of a biological pre-treatment strategy using the cellulolytic fungus Trichoderma viride was found for standardized bio-waste when applying high nutrient concentrations. Although the pre-treatment had a significantly beneficial effect, causes and mechanisms underlying the increased biogas yield were still awaiting elucidation. Therefore, the overall aim of the project Trichtreat was the systematic biochemical and microbiological investigation of the aerobic pre-treatment process using T. viride for subsequent anaerobic digestion. In extensive experiments applying different amounts of standardized bio-waste the mode of action of the biological pre-treatment using the cellulolytic fungus T. viride during the pre-treatment and the subsequent anaerobic digestion phase was evaluated. It could be shown, that the application of high nutrient concentrations during the pre-treatment increased the biogas- and methane yields in the anerobic digestion step. However, this effect was not due to an increased disintegration of the substrate but rather to a decrease of overload phenomena due to the fungus application during the pre-treatment. At lower nutrient concentrations an effect on digestion kinetics was observed during the first days of anaerobic digestion, the overall methane yield, however, remained the same when comparing not- and pretreated samples. Similar results were found for other "real" substrates like maize silage and corn straw. Therefore, in order to causally describe the mode of action of T. viride pre-treatment a new path was used replacing the mixed bio-waste substrate by a strictly defined one. In the course of these investigations a positive effect of T. viride pre-treatment on the anaerobic digestion kinetics rather than on overall biogas- and methane yield was found; however, an impact on the cellulolytic (organisms of the genera Acetivibrio, Ruminofilibacter, Herbinix und Fibrobracter) and the methanogenic (organisms of the genera Methanosarcina, Methanosaeta und Methanobacterium) microbial community could be figured out.