CONICET | Buscador de Institutos y Recursos Humanos

Modern technological and industrial applications frequently use microorganisms as biocatalysts for the optimization of processes. This strategy is more efficient when microorganisms are grown in biofilms, which are the most frequent microbial way of life in nature. These multi-species communities grow at virtually every interface and are the focus of intense research all over the world. Notably, the present knowledge on biofilms composed by hyperhalophilic microorganisms is still limited. In these work a strain of Halobacterium sp. an hyperhalophilic archaeon isolated from La Colorada Grande saltern (La Pampa province, Argentina) was grown forming biofilms onto glass surfaces aiming at evaluating their structure and kinetics of growth. For these aims biofilm was performed in flow-through cells that allowed the direct observation at the phase contrast microscope and the structural study comprising optic sectioning and digital image analysis. Thereby biofilm thickness and cell coverage at different focal planes were determined over the time of growth. Indeed, these parameters were measured on biofilms developed under standard salinity (25% total salts) and under ionic stress generated by low salt concentration (18% total salts), as a way of representing natural environmental pressure on biofilm persistence. Initial observations were related to the unusual elongation of individual cells during early stages of biofilm development. Upon colonizing the surface they elongated to around 6 µm, reaching three times the average length observed at the same growth stage in planktonic cultures. Notably, as biofilms grew the length of cells returned to the typical value, suggesting that elongation may be a colonization related strategy. Under low salinity conditions this behavior was also observed, but in a lower degree.