Methanotrophically Mediated Bioaggregation to Control Sand Dust in Qatar

Sandstorms are commonplace in many parts of the world including Qatar, these storms have significant negative impacts on the economy, environment, infrastructure, and public health. Traditional prevention techniques use chemical stabilizers and cementing agents; however, their application is not only expensive, but may also have negative impacts on the environment and public health. Recently steep regulations on chemical grouts from Japan and the United States has caused many countries to follow suit and propose bans. In turn organic polymers and microbial biogrout have been proposed. However, organic polymers still have significant negative impacts on the environment; while biogrout has proven effective, it has not been tested for surface stabilization and releases harmful ammonia as a byproduct. Our research team has proposed using native extracellular polysaccharide (EPS) producing bacteria, specifically methanotrophic bacteria, for bioaggregation. EPS, sugars formed by the cell and then released outside the cell wall, make up much of the adhesive characteristics of biofilm and have been known to naturally form microbial crusts in Chinese desert sand. EPS is composed of a wide variety of sugars, not all of which are useful for stability, hence multiple species and their EPS must be tested. The proposed technique would involve application of an EPS producing methanotrophic bacterial culture to the sand's surface, or, application of the liquid culture followed by application of purified EPS. Methanotrophic bacteria are capable of using Methane as a carbon source and can produce large amounts of EPS and have been widely studied. The preference is for native methanotrophic bacteria to be used, to prevent introduction of non-native species or genes, and to minimize the disruption to the native ecosystem. We have collected native methanotrophic bacteria from Qatar sand. Samples of sand were incubated in Nitrate Mineral Salt (NMS) media under a 1:1 headspace ratio of air to Methane, and then streaked onto agar plates of the same media. The plates showed growth and EPS production. Since the media contains no carbon source the only accessible carbon source is the methane in the headspace so the bacteria can be assumed to be Methanotrophic. This will be confirmed along with determining species identifications through 16S rRNA Gene Amplicon Sanger Sequencing of the isolates; however, at the time of submission for this abstract sequencing and interpretation of the data are still underway. Until native methanotrophic bacteria can be identified and researched, two well studied strains of Methanotrophs – Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b – are being used for preliminary EPS testing. Application of purified EPS, extracted with an Ethanol precipitation extraction method, to sand has shown signs of significant aggregation, along with increases in shear strength. Once a strain of bacteria is chosen by the research team, and the EPS production optimized, a lab scale bioreactor will be built to produce large amounts of EPS for lab scale sand stabilization studies. Lab scale studies will monitor time dependent changes in shear strength during application, microbial community changes, and ability to withstand critical threshold wind velocities. Future plans include field scale studies and the construction of a fluidized bed bioreactor for production of the liquid medium and EPS. Methanotrophic bacteria are easily adapted to large bioreactors and in situ applications. Bioaggregation with EPS producing bacteria would potentially provide an environmental friendly application for the prevention of sandstorms, utilizing methane – an indigenous resource to Qatar – for cost saving benefits.