Exploring hydrocarbonoclastic bacterial communities in the estuarine surface microlayer

Bacteria that degrade polycyclic aromatic hydrocarbons (PAHs) in the estuarine surface microlayer (SML) of the Ria de Aveiro, Portugal—which is chronically polluted with oil hydrocarbons (OH)—were isolated and characterized; Pseudomonas was dominant among the PAH-degrading bacteria. Screening for PAH dioxygenase genes detected almost identical nahAc genes (encoding the alpha subunits of naphthalene dioxygenase) in 2 phylogenetically distinct isolates: Pseudomonas sp. and an unknown species of the family Enterobacteriaceae; this suggested that horizontal transfer of nah genes might be involved in PAH degradation in the SML. We also investigated the effect of PAH contamination on the spatial variability of the bacterioneuston along a gradient of pollution in the estuarine system of the Ria de Aveiro. Culture-independent techniques—fluorescence in situ hy - bridization (FISH) and denaturing-gradient gel electrophoresis (DGGE)—revealed a similar structure among the bacterioneuston communities along the estuary. In contrast, we detected differences in the relative abundance and diversity of organisms of the Gammaproteobacteria, including those of the genus Pseudomonas (which belongs to the Gammaproteobacteria). This is the first insight into the hydrocarbonoclastic bacterial communities in the SML of an estuarine area polluted with hydrocarbons. Our findings highlight the importance of SML-adapted hydrocarbonoclastic bacterioneuston as a potential source of new PAH-degrading bacteria (including new pseudomonads) with potential use in the bioremediation of hydrocarbon-polluted ecosystems.

Bacterial collagenases: a review

Bacterial collagenases are metalloproteinases involved in the degradation of the extracellular matrices of animal cells, due to their ability to digest native collagen. These enzymes are important virulence factors in a variety of pathogenic bacteria. Nonetheless, there is a lack of scientific consensus for a proper and well-defined classification of these enzymes and a vast controversy regarding the correct identification of collagenases. Clostridial collagenases were the first ones to be identified and characterized and are the reference enzymes for comparison of newly discovered collagenolytic enzymes. In this review we present the most recent data regarding bacterial collagenases and overview the functional and structural diversity of bacterial collagenases. An overall picture of the molecular diversity and distribution of these proteins in nature will also be given. Particular aspects of the different proteolytic activities will be contextualized within relevant areas of application, mainly biotechnological processes and therapeutic uses. At last, we will present a new classification guide for bacterial collagenases that will allow the correct and straightforward classification of these enzymes.