Volatiles produced by the mycophagous soil bacteriumCollimonas

Abstract

It is increasingly recognized that volatile organic compounds play an import role during interactions between soil microorganisms. Here, we examined the possible involvement of volatiles in the interaction of Collimonas bacteria with soil fungi. The genus Collimonas is known for its ability to grow at the expense of living fungi (mycophagy), and antifungal volatiles may contribute to the attack of fungi by these bacteria. We analyzed the composition of volatiles produced by Collimonas on agar under different nutrient conditions and studied the effect on fungal growth. The volatiles had a negative effect on the growth of a broad spectrum of fungal species. Collimonas bacteria did also produce volatiles in sand microcosms supplied with artificial root exudates. The production of volatiles in sand microcosms was enhanced by the presence of fungi. The overall picture that we get from our study is that antifungal volatiles produced by Collimonas could play an important role in realizing its mycophagous lifestyle. The current work is also interesting for understanding the ecological relevance of volatile production by soil bacteria in general as we found strong influences of root exudates composition and incubation conditions on the spectrum of volatiles produced.

Volatile affairs in microbial interactions

“…Furthermore, exposure to bacterial volatiles has been reported to change fungal morphology, enzyme activity and gene expression (Wheatley, 2002;Vespermann et al, 2007;Minerdi et al, 2008Minerdi et al, , 2009Kai et al, 2009;Garbeva et al, 2011Garbeva et al, , 2014b. For example, activity of laccases and tyrosinases can be strongly affected by bacterial volatiles (Wheatley, 2002).…”

“…Sensitivity to volatiles can strongly differ between fungal species and the extent of inhibition depends on the individual bacteria-fungus or fungus-fungus interaction (Kai et al, , 2009Vespermann et al, 2007;Garbeva et al, 2014b). Several independent studies have reported that F. solani is not much affected by bacterial volatiles, whereas Pythium species (oomycetes) are highly sensitive to bacterial volatiles (Kai et al, 2009;Effmert et al, 2012;Garbeva et al, 2014a,b).…”

Mining into interspecific bacterial interactions

“…The high abundance of sulfur containing volatiles in this study can be related to the cultivation of the tested bacteria on 1/10 th TSBA growth media. Several studies indicated that the composition of the volatile blend greatly depends on the growth media composition and the growth conditions (Schulz et al, 2004;Schulz and Dickschat, 2007;Blom et al, 2011;Garbeva et al, 2014b). The high amount of dimethyl di-and trisulfide detected in both monocultures and interactions indicate that these compounds are commonly produced.…”

“…The high amount of dimethyl di-and trisulfide detected in both monocultures and interactions indicate that these compounds are commonly produced. Many studies have shown that bacterial volatiles play a major role in soil fungistasis (Zou et al, 2007;Garbeva et al, 2011a;Garbeva et al, 2014b;van Agtmaal et al, 2015).…”

“…AD106 (Class: Actinobacteria) GenBank: KJ685317. The bacterial isolates were precultured from -80 °C glycerol stocks on 1/10 th TSBA (5.0 gL -1 NaCl, 1.0 gL To test the effect of bacterial volatile compounds on bacterial growth and colony morphology three indicator bacteria were used: E. coli WA321, S. aureus 533R4 (Meyer and Schleifer, 1978; and S. marcescens P87 (Garbeva et al, 2014b). All three indicator bacteria were pre-cultured from -80 °C glycerol stocks either on LB-A media (LB-Medium Lennox, Carl Roth GmbH + Co. KG, Netherlands, art.no.…”