Recently the potential of enzymes for surface hydrophilisation and/or functionalisation of polyethyleneterephthalate (PET) and polyamide (PA) has been discovered. However, there was no correlation between enzyme class/activity (e.g. esterase, lipase, cutinase) and surface hydrolysis of these polymers and consequently no simple assay to estimate this capability. Enzymes active on the model substrates bis (benzoyloxyethyl) terephthalate and adipic acid bishexyl-amide, were also capable of increasing the hydrophilicity of PET and PA. When dosed at the identical activity on 4-nitrophenyl butyrate, only enzymes from Thermobifida fusca, Aspergillus sp., Beauveria sp. and commercial enzymes (TEXAZYME PES sp5 and Lipase PS) increased the hydrophilicity of PET fibres while other esterases and lipases did not show any effect. Activity on PET correlated with the activity on the model substrate. Hydrophilicity of fibres was greatly improved based on increases in rising height of up to 4.3 cm and the relative decrease of water absorption time between control and sample of the water was up to 76%. Similarly, enzymes increasing the hydrophilicity of PA fibres such as from Nocardia sp., Beauveria sp. and F. solani hydrolysed the model substrate; however, there was no common enzyme activity (e.g. protease, esterase, amidase) which could be attributed to all these enzymes.

Background Biological control is an environmentally sound and effective means of reducing pathogeninduced damage to agriculture using natural antagonists. Paenibacillus is a cosmopolitan and ubiquitously occurring bacterial genus with antagonistic activity against phytopathogens. Many species and strains with promising potential for plant growth promotion and biocontrol of pathogens have been identified since Paenibacillus was first described 20 years ago. Nevertheless, important questions regarding the colonization of plants, and the mode of action of Paenibacillus remain unanswered. Scope This review focuses on the occurrence of Paenibacillus in microbial metagenomes, the endophytic lifestyle of Paenibacillus, and the function of Paenibacillus-derived volatile organic compounds (VOCs) combining actual literature with our own results.Conclusions This review provides new insights into the endophytic lifestyle of Paenibacillus and discusses strain-specific and system-dependent growth promotion effects on plants. VOCs, in particular pyrazine derivatives emitted by Paenibacillus, showed high activity against other organisms. This suggests that VOCs play an important role in communication and interaction. Overall, Paenibacillus strains demonstrate promising potential not only for sustainable agriculture and biological control, but also as a source for novel bioactive volatiles.

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This work describes newly isolated organisms and their potential to modify the surface of polyethylene terephthalate (PET). Out of the different screening processes, four bacterial and five fungal strains were isolated. A PET model substrate was synthesized (bis (benzoyloxyethyl) terephthalate) and used in the screening process, mimicking the polymer in its crucial properties and having the advantage of defined hydrolysis products. On this model substrate, extracellular enzyme preparations from the isolated microorganisms showed a maximum activity of 8.54 nkat/L. All enzyme preparations showed esterase activity on p-nitrophenyl-acetate while no activity was found on p-nitrophenyl decanoate or p-nitrophenyl palmitate. Increased hydrophilicity of PET fabrics after enzyme treatment was found based on rising height and water dissipation measurements.

Volatile organic compounds (VOCs) produced by microorganisms are known both for their effect on pathogens and their role as mediators in various interactions and communications. Previous studies have demonstrated the importance of VOCs for ecosystem functioning as well as their biotechnological potential, but screening for bioactive volatiles remained difficult. We have developed an efficient testing assay that is based on two multi-well plates, separated by a sealing silicone membrane, two tightening clamps, and variable growth media, or indicators. The experiment design as presented here is a novel and robust technique to identify positive as well as negative VOC effects on the growth of a target organism and to test for specific substances e.g., hydrogen cyanide which can be detected with a suitable indicator. While the first pre-screening assay is primarily based on indicator color change and visible growth diameter reduction, we also introduce an advanced and quantitatively precise experiment design. This adaptation involves qPCR-based quantification of viable target cells after concluding the treatment with VOCs. Therefore, we chose preselected active isolates and compared the partial 16S rRNA gene copy number of headspace-exposed E. coli with non-treated controls. Separately obtained headspace SPME and GC/MS-based profiles of selected bacterial isolates revealed the presence of specific and unique signatures which suggests divergent modes of action. The assay was evaluated by screening 100 isolates of lung lichen-associated bacteria. Approximately one quarter of the isolates showed VOC-based antibacterial and/or antifungal activity; mainly Pseudomonas and Stenotrophomonas species were identified as producers of bioactive volatiles.