Removal of phytotoxic compounds from torrefied grass fibres by plant-beneficial microorganisms

Abstract

We aimed to select microorganisms colonizing torrefied grass fibres (TGF) and simultaneously reducing the phytotoxicity which appeared after heat treatment of the fibres. Eighty-eight bacterial strains and one fungus, previously isolated from a sequential enrichment experiment on torrefied fibres and extracts, were tested separately for their capacity to decrease phytotoxicity. Eleven of the bacterial strains and the fungus significantly reduced phytotoxicity. These organisms were checked for their ability to grow on agar containing phenol, 2-methoxyphenol, 2,6-dimethoxyphenol, 2-furalaldehyde, pyrrole-2-carboxaldehyde and furan-2-methanol as sole carbon sources. The fungus F/TGF15 and the bacterial strain 66/TGF15 were able to grow on all six compounds. Strains 15/TGE5, 23/TGE5, 43/TGE20, 56/TGF10 and 95/TGF15 grew on two to four compounds, and strain 72/TGF15 only on one compound. Strains 31/TGE5, 34/TGE5, 48/TGE20 and 70/TGF15 did not grow on any of the single toxic compounds. GC analyses of torrefied grass extracts (TGE) determined which compounds were removed by the microorganisms. F/TGF15 was the only isolate depleting phenol, 2-methoxyphenol, 2-dihydrofuranone and pyrrole-2,5-dione-3-ethyl-4-methyl. Strains 15/TGE5, 23/TGE5, 31/TGE5 and 56/TGF10, and the fungus depleted 2-furalaldehyde, 2-furan-carboxaldehyde-5-methyl, pyrrole-2-carboxaldehyde, 5-acetoxymethyl-2-furaldehyde and benzaldehyde-3-hydroxy-4-methoxy. These promising candidates for colonizing and simultaneously reducing the phytotoxicity of TGF were affiliated with Pseudomonas putida, Serratia plymuthica, Pseudomonas corrugata, Methylobacterium radiotolerans and Coniochaeta ligniaria.

Charcoal Volatile Matter Content Influences Plant Growth and Soil Nitrogen Transformations

“…Th e GC-MS analysis showing the presence of phenolic compounds provides evidence that the high-VM charcoal contained readily available C sources for soil microorganisms. Th ere is ample evidence that both fungi and bacteria utilize phenolic compounds as a sole source of C (Saravanan et al, 2008;Stoilova et al, 2006;Trifonova et al, 2008). Th e results from our incubation studies (Exp.…”

“…6a) contained a range of compounds including butyrolactone, phenol, cresol, mequinol, ethyl phenol, p-ethyl guaiacol, and syringol (Bocchini et al, 1997). Phenol is known to be phytotoxic (Wang et al, 2002), but both phenol and cresol are utilized as a C source by soil microorganisms (Saravanan et al, 2008;Trifonova et al, 2008). Th e chromatogram for the low-VM charcoal (Fig.…”

Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry for Analysis of VOCs Produced by Phytophthora cinnamomi

“…The majority of them have been isolated using classical enrichment on furfural as a carbon source (25,46,49). However, most of these isolated microorganisms are aerobic Gram-negative bacteria, with only three fungi reported as furfural degraders (23,39,51). Rosche et al (35) found 14 filamentous fungi that could biotransform benzaldehyde.…”

Phytotoxicity, not nitrogen immobilization, explains plant litter inhibitory effects: evidence from solid‐state 13C NMR spectroscopy

“…Hundreds of organic compounds with phytotoxic activity have been extracted from plant tissues, purified and identified (e.g. Rice, 1984;Rizvi & Rizvi, 1992;Reigosa et al, 2006), but the link between these single chemicals and the inhibitory effect of plant detritus has only been demonstrated in a limited number of cases (An et al, 2001;Trifonova et al, 2008). Recent studies have reported that plant litter is composed of a milieu of thousands of unique molecules that change during decomposition (Wallenstein et al, 2010).…”