Arthropeptide A, an antifungal cyclic tetrapeptide from Arthrobacter psychrophenolicus isolated from disease suppressive compost

Abstract

In an effort to describe bioactive antifungal compounds from antagonistic bacteria with potential for biocontrol of plant pathogens, a strain of Arthrobacter psychrophenolicus was collected from plant disease suppressive compost prepared from composted material of marine origin. Few natural products have been characterized from the non-filamentous Actinobacteria genus Arthrobacter. A new cyclic tetrapeptide, cyclo-(L-Pro-L-Leu-L-γHyp-L-Tyr); arthropeptide A (1), was isolated from the EtOAc soluble culture filtrate extract of A. psychrophenolicus M9-17 grown in MOLP broth. Its structure was confirmed by HRMS, interpretation of NMR data, and a modified Marfey’s method. Arthropeptide A (1) displayed antifungal activity towards Alternaria alternata, the causal agent of disease in numerous host plant species, which had shown the previous susceptibility to A. psychrophenolicus. The newly identified compound may be responsible, in part, for the inhibitory activity of the bacterium against fungal plant pathogens.

Graphical Abstract

Keywords:

• Arthrobacter
• cyclic tetrapeptide
• natural products
• biocontrol

Acknowledgements

We thank Michael Darnowski and Dr. Chris Boddy (University of Ottawa) for the acquisition of NMR data, and Dr. Justin Renaud (Agriculture and Agri-Food Canada, London) for the acquisition of HRMS data.

Declaration statement

All authors declare that there is no conflict of interest associated with this work.

Additional information

Funding

Financial support was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC; RGPIN-2020-06406) to Tyler J. Avis.