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Use of compost is a common agricultural practice. It improves soil fertility by adding nutrients and plant growth promoting (PGP) microorganisms. The role of bacterial-fungal interactions for compost-driven fertilization, however, is still poorly understood. In this study, we investigated whether putative PGP bacteria associate to and disperse along mycelia of fungal isolates. A ‘Fungal highway column system’ was used to isolate and characterize fungal—bacterial couples derived from commercial compost (C), non-composted bulk soil (BS) and rhizosphere soil with compost application (RSC). Bacterial-fungal couples were identified by 16S and 18S rRNA gene sequencing and isolated bacteria were tested for representative PGP traits. Couples of fungi and associated migrator bacteria were isolated from C and RSC only. They included the fungal genera Aspergillus, Mucor, Ulocladium, Rhizopus and Syncephalastrum, and the bacterial genera Rhodococcus, Bacillus, Pseudomonas, Agrobacterium, Glutamicibacter and Microbacterium. Many of migrator bacteria in RSC and C showed PGP traits (e.g., tryptophane—induced auxin synthesis or phytate mineralizing activity) suggesting that fungi contained in C and RSC allow for dispersal of putative PGP bacteria. Next to being provider of nutrients, compost may therefore be source for PGP bacteria and fungal mycelia serving as networks for their efficient dispersal.

The interest in magnesium-based materials is promoted by their biocompatibility, their bioresorbability, and their recently discovered antibacterial potential. Until now, the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated superhydrophobic coatings on a magnesium-based alloy, and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate-buffered saline. It was shown that the immersion of such coatings in bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of the superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties in magnesium dissolution and hence in dispersion medium alkalization, eventually leading to the inhibition of magnesium substrate degradation. The electrochemical data obtained for superhydrophobic samples in continuous contact with corrosive bacterial dispersions for 48 h indicated a high level of anticorrosion protection.