Muna Y. Hindiyeh

Biogeographical diversity of leaf-associated microbial communities from salt-secreting Tamarix trees of the Dead Sea region.

The leaves of Tamarix, a salt-secreting desert tree, form an extreme niche that harbors a unique microbial community. In view of the global distribution of this tree, its island-like phyllosphere is highly suitable for studying microbial diversity along geographical gradients. Here we present an analysis of microbial community diversity using leaf surface samples collected at six different sites, on both sides of the Dead Sea, over a period of one year. Biodiversity analysis of denaturing gradient gel electrophoresis (DGGE) patterns of the bacterial 16S rRNA gene revealed a significant degree of bacterial community similarity within trees sampled at the same site, much higher than the similarity between trees from different geographical locations. Statistical analysis indicated that the degree of similarity was negatively correlated with the distance between sampling sites, and that a weak correlation existed between diversity and leaf pH.

Widespread formation of methane by Cyanobacteria in aquatic and terrestrial environments

Abstract Evidence is accumulating to challenge the paradigm that biogenic methanogenesis, considered a strictly anaerobic process, is exclusive to Archaea. We demonstrate that Cyanobacteria living in marine, freshwater and terrestrial environments produce methane at substantial rates under light, dark, oxic and anoxic conditions, linking methane production with light driven primary productivity in a globally relevant and ancient group of photoautotrophs. Methane production, attributed to cyanobacteria using stable isotope labelling techniques, was enhanced during oxygenic photosynthesis. We suggest that formation of methane by Cyanobacteria contributes to methane accumulation in oxygen-saturated marine and limnic surface waters. In these environments, frequent cyanobacterial blooms are predicted to further increase due to global warming potentially having a direct positive feedback on climate change. We conclude that this newly identified source contributes to the current natural methane budget and most likely has been producing methane since Cyanobacteria first evolved on Earth.Evidence is accumulating to challenge the paradigm that biogenic methanogenesis, traditionally considered a strictly anerobic process, is exclusive to Archaea. Here we demonstrate that Cyanobacteria living in marine, freshwater and terrestrial environments produce methane at substantial rates under light and dark oxic and anoxic conditions, forming a link between light driven primary productivity and methane production in globally relevant group of phototrophs. Biogenic methane production was enhanced during oxygenic photosynthesis and directly attributed to the cyanobacteria by applying stable isotope labelling techniques. We suggest that formation of methane by Cyanobacteria may contribute to methane accumulation in oxygen-saturated surface waters of marine and freshwater ecosystems. Moreover, in these environments, cyanobacterial blooms already do, and might further occur more frequently during future global warming and thus have a direct feedback on climate change. We further highlight that cyanobacterial methane production not only affects recent and future global methane budgets, but also has implications for inferences on Earth’s methane budget for the last 3.5 billion years, when this phylum is thought to have first evolved.

Corporate Environmental Responsibility in Jordan: The Potential and Limits

The world is facing unique environmental challenges. There is a record loss of biodiversity and long-term damage to ecosystems; pol-lution of the atmosphere and the consequences of climate change; waste production and disposal; natural resource depletion; the impact of using chemicals and toxic substance disposal; damaged aquatic ecosystems and land degradation. There is a need to iden-tify the options to reduce and eliminate unsustainable volumes and patterns of production and consumption to ensure that the resource consumption per person becomes sustainable.