Biohydrogen Production From Untreated Lignocellulosic Biomass Using Thermophiles

The desire for a greener world with renewable energy source and to reduce the anthropogenic pollutant emissions has shifted the research interest toward biofuels.  Hydrogen, being a highly energy efficient, environmentally friendly, and renewable source, has been given importance in the past few years.  The present hydrogen production processes are limited by the substrate shortage, operation costs, hazardous chemicals usage and production, complex designs, and their high set-up costs.  Biohydrogen production form the lignocellulosic biomass using microorganisms offers promising alternatives for the costly chemical and physical processes.  However, pretreatment costs of the lignocellulosic biomass often make the biohydrogen production process less cost-effective.  Therefore, the present research is focused on using the untreated biomass so as to lower the cost of hydrogen production.  Locally available lignocellulosic biomass (Prairie Cord Grass -PCG) was used for the biohydrogen production using thermophillic microbes isolated from Thermopolis hot springs of Wyoming.  Dark fermentation (60°C) was carried in the 135-ml serum bottles containing 100 ml growth medium amended with 1% untreated PCG and hydrogen was measured.  A maximum cumulative yield of 8.68 mL/g-dry PCG was achieved under optimum conditions of temperature and pH. Utilization of untreated PCG and metabolite production (lactic and acetic acids) profiles was also compared.  The results show that thermophillic consortium was able to convert untreated PCG into hydrogen in one step. This thermophillic consolidated bioprocess will likely impact ongoing multiple-step conversion processes of lignocellulosic biomass to hydrogen by providing a more efficient and economical process.