Developing a microbial consortium for removing nutrients in dishwasher wastewater: towards a biofilter for its up-cycling.

Microbial consortia are effective biofilters to treat wastewaters, allowing for resource recovery and water remediation. To reuse and save water in the domestic cycle, we assembled a suspended biofilm, a 'biofilter' to treat dishwasher wastewater. Bacterial monocultures of both photo- and heterotrophs were assembled in an increasingly complex fashion to test their nutrient stripping capacity. This 'biofilter' is the core of an integrated system (Zero Mile System) devoted to reusing and upcycling of reconditioned wastewater, partly in subsequent dishwasher cycles and partly into a vertical garden for plant food cultivation. The biofilter was assembled based on a strain of the photosynthetic, filamentous cyanobacterium Trichormus variabilis, selected to produce an oxygen evolving scaffold, and three heterotrophic aerobic bacterial isolates coming from the dishwasher wastewater itself: Acinetobacter, Exiguobacterium and Pseudomonas spp. The consortium was constructed starting with 16 isolates tested one-to-one with T. variabilis and then selecting the heterotrophic microbes up to a final one-to-three consortium, which included two dominant and a rare component of the wastewater community. This consortium thrives in the wastewater much better than T. variabilis alone, efficiently stripping N and P in short time, a pivotal step for the reuse and saving of water in household appliances.

Structural characterization and biological activity of Crabrolin peptide isoforms with different positive charge.

The search of antimicrobial peptides (AMP) as candidates for the development of antibiotics is an active research field. In this paper we investigated the role of charged residues in antimicrobial activity by using as a template the previously characterized crabrolin peptide. Mutant peptides in which the charge was diminished (Crabrolin Minus) or increased (Crabrolin Plus) were assayed for their ability to inhibit bacterial growth and to bind model bacterial membranes or lipopolysaccharide (LPS). Structural analysis of both peptides by means of CD, NMR and Molecular Dynamics was also performed and correlated to the biological data. Although native Crabrolin (WT) displays smaller efficacy than other antibacterial peptides with similar length, Crabrolin Plus displays a significant antimicrobial activity while Crabrolin Minus is not active, thus confirming the key role of the positive charge for interacting with the bacterial membrane. Moreover, our results show that charge position has no effect on the helical propensity of the peptides but drastically affects their antimicrobial activity. Antimicrobial activity versus Gram-positive and Gram-negative bacteria, as well as specific interaction with LPS, suggest multiple binding modes for the active peptide.

Parchment processing and analysis: Ionizing radiation treatment by the REX source and multidisciplinary approach characterization.

Library material, and thus parchment, is frequently subjected to bio-deterioration processes caused by microorganisms. Fungi and bacteria cause alterations in the parchment inducing, in some cases, even the partial detachments of the surface layer and the loss of any text present on it. An important contribution to disinfection of the cultural heritage artefacts is given by the use of ionizing radiation. In this work, a preliminary study on the applicability of X-ray radiation as treatment for bio-deterioration removal is proposed. The results on the microbial growth after different irradiation treatments are shown in order to detect the dose protocol for the bio-degradation removal. Furthermore, the evaluation of the irradiation effects on the parchment microstructure is presented in order to define the applicability of the method on parchment artefacts.