Coniochaeta Ligniaria Research Articles

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

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.

Fungal metabolism of fermentation inhibitors present in corn stover dilute acid hydrolysate

Use of agricultural residues for ethanol production requires pretreatment of the material to facilitate release of sugars. Physical–chemical pretreatment of lignocellulosic biomass can, however, give rise to side-products that may be toxic to fermenting microorganisms and hinder utilization of sugars obtained from biomass. Potentially problematic compounds include furan aldehydes formed by degradation of sugars, organic acids released from hemicellulose side-groups, and aldehydes and phenolics released from lignin. A fungal isolate, Coniochaeta ligniaria NRRL30616, metabolizes furfural and 5-hydroxymethylfurfural (HMF) as well as aromatic and aliphatic acids and aldehydes. NRRL30616 grew in corn stover dilute-acid hydrolysate, and converted furfural to both furfuryl alcohol and furoic acid. Hydrolysate was inoculated with NRRL30616, and the fate of pretreatment side-products was followed in a time-course study. A number of aromatic and aliphatic acids, aldehydes, and phenolic compounds were quantitated by analytical extraction of corn stover hydrolysate, followed by HPLC–UV–MS/MS analysis. Compounds representing all of the classes of inhibitory side-products were removed during the course of fungal growth. Biological abatement of hydrolysates using C. ligniaria improved xylose utilization in subsequent ethanol fermentations.

External and internal fungal flora of pine sapwood (Pinus sylvestris L.) specimens in above-ground field tests at six different sites in south-west Germany

Abstract The occurrence of fungal species on pine sapwood samples obtained from an above-ground field test study was analysed by terminal restriction fragment length polymorphism (T-RFLP), cloning, and sequencing. Samples were taken from eight double-layer set-ups that were exposed to the environment at six different locations in south-west Germany. The occurrence of fungal species was correlated with decay intensity and rot types on one hand, and characteristics of the test sites, such as precipitation, average temperature and height above sea level on the other hand. In total, 62 different fungal species were found based on T-RFLP, cloning and sequencing. Of the 39 species that were found four or more times, 30 were ascomycetes, five were basidiomycetes, and four could not be classified. The most common fungus found in this study was Coniochaeta ligniaria ((Grev.) Cooke), a soft rot fungus that occurred in 87 of 152 samples (57%). No single factor at the test sites seemed to be decisive for the abundance of fungal species or decay intensity. Within the first years of this study, soft rot fungi was found more frequently in pine sapwood specimens than basidiomycetes.

Lignocellulose-degrading enzymes produced by the ascomycete Coniochaeta ligniaria and related species: Application for a lignocellulosic substrate treatment

Lignocellulose-degrading microorganisms are of interest for biomass upgrading. In a previous work, we isolated the ascomycete Coniochaeta ligniaria NRRL 30616 that metabolized phenolics and furans in lignocellulosic acid hydrolysates. This fungal isolate was investigated in the present work for the ability to produce lignocellulose-degrading enzymes during batch cultivation using different substrates as carbon source. This microorganism produced cellulase, xylanase and two lignin peroxidases (manganese peroxidase, MnP and lignin peroxidase, LiP), but laccase activity was not detected. The same enzyme activities were also found in 23 related fungal strains, and C. ligniaria NRRL 30616 showed the highest levels for some of the enzymes. Treatment of pepper plant residues (PPR) with this fungus was monitored during 20 days in solid and semisolid-state cultures. It was found that all enzymes initially detected were produced under these conditions at the early culture stages (5 days) and lignocellulose polymers were consequently degraded. Losses of about 75%, 50% and 40% were obtained for hemicellulose, cellulose and lignin, respectively, in semisolid cultures after 20 days. The lignocellulolytic activity of C. ligniaria detected in this study may be exploited for lignocellulosic biomass treatment.

Bioabatement to Remove Inhibitors from Biomass-Derived Sugar Hydrolysates

Bioabatement is a potential method to remove inhibitory compounds from lignocellulose hydrolysates that could be incorporated into a scheme for fermentation of ethanol from cellulose. Coniochaeta ligniaria NRRL30616, an Ascomycete that metabolizes furfural and 5-hydroxymethylfurfural, is a unique strain that may be useful for detoxifying biomass sugars. NRRL30616 and 23 related fungal strains were screened for the ability to metabolize furans and grow in dilute-acid hydrolysate of corn stover. NRRL30616 was the best strain for removal of inhibitors from hydrolysate, and abatement of hydrolysate by inoculation with the strain allowed subsequent yeast fermentation of cellulose to ethanol.

Isolation of microorganisms for biological detoxification of lignocellulosic hydrolysates.

Acid pretreatment of lignocellulosic biomass releases furan and phenolic compounds, which are toxic to microorganisms used for subsequent fermentation. In this study, we isolated new microorganisms for depletion of inhibitors in lignocellulosic acid hydrolysates. A sequential enrichment strategy was used to isolate microorganisms from soil. Selection was carried out in a defined mineral medium containing a mixture of ferulic acid (5 mM), 5-hydroxymethylfurfural (5-HMF, 15 mM), and furfural (20 mM) as the carbon and energy sources, followed by an additional transfer into a corn stover hydrolysate (CSH) prepared using dilute acid. Subsequently, based on stable growth on these substrates, six isolates--including five bacteria related to Methylobacterium extorquens, Pseudomonas sp, Flavobacterium indologenes, Acinetobacter sp., Arthrobacter aurescens, and one fungus, Coniochaeta ligniaria--were chosen. All six isolates depleted toxic compounds from defined medium, but only C. ligniaria C8 (NRRL 30616) was effective at eliminating furfural and 5-HMF from CSH. C. ligniaria NRRL 30616 may be useful in developing a bioprocess for inhibitor abatement in the conversion of lignocellulosic biomass to fuels and chemicals.

The Conidial Stage of Coniochaeta ligniaria: Morphology and Cytology

SUMMARYThe conidial stage of Coniochaeta ligniaria is described. In morphology, it resembles the imperfect stages of several other Coniochaeta species. A typical mitotic cycle was found to be operative in the hyphae. The chromosome number, based on mitotic prophase (prometaphase) and metaphase counts, tentatively is 6. Anaphase irregularities, apparently frequent, are described.

The Conidial Stage of Coniochaeta Ligniaria: Morphology and Cytology

The conidial stage of Coniochaeta ligniaria is described. In morphology, it resembles the imperfect stages of several other Coniochaeta species. A typical mitotic cycle was found to be operative in...