Improved endoglucanase production and mycelial biomass of some ericoid fungi

AMB Express, Jan 2017

Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.

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Improved endoglucanase production and mycelial biomass of some ericoid fungi

Adeoyo et al. AMB Expr Improved endoglucanase production and mycelial biomass of some ericoid fungi O. R. Adeoyo 0 B. I. Pletschke 0 J. F. Dames 0 0 Department of Biochemistry and Microbiology, Rhodes University , P.O. Box 94, Grahamstown 6140 , South Africa Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study. Endoglucanase; Ericoid; Endophytic fungi; Mycelial biomass - Introduction The soils of temperate, boreal forests and heathlands are characteristically enriched with a large number of soil microbes that include ericoid mycorrhizal (ERM) and dark septate root endophytic (DSE) fungi. Roots of ericaceous plants harbour these fungi, conferring eco-physiological benefits to the host (Bizabani and Dames 2015). A mutualistic association is usually formed between the plant family Ericaceae and related fungal members (Cairney and Meharg 2003). Ericoid mycorrhizas are characterized by densely packed intracellular fungal coils that are formed in the epidermal cells of the fine hair roots of their host plant while establishing a loose hyphal network outside of the hair roots (Smith and Read 2008). These thin hyphal coils within the cortical cells serve as interfaces for nutrient exchange between the symbionts (Vohnik et  al. 2009). The primary function of the ERM fungus is to facilitate the utilisation of organic complexes as a source of nutrients for their host plant and in return, the fungus acquires photosynthetic carbon from the host for the completion of their life cycle (Pearson and Read 1975). Hymenoscyphus ericae is a major ericoid fungus that has been extensively investigated for its ability to grow on a variety of complex organic substrates that include carboxymethylcellulose (CMC) (Leake and Miles 1996). ECM associations enable host plants to survive in soils characterized by impoverished nutrient status, e.g. acidic, nitrogen and phosphorus deficient soils (Read 1996). The fungi selected for this study were isolated from the host plants belonging to genus Erica. The genus Erica is a large varied taxon containing approximately 850 species (Oliver 2000). DSE fungi are conidial or sterile ascomycetes that colonize living plant roots without causing apparent negative effects such as tissue disorganization (Jumpponen and Trappe 1998). Several DSE fungi have been found to form symbiotic relationships with their host plant (Usuki and Narisawa 2007). DSE colonization has been identified in about 600 plant species which represent about 320 genera and 114 families (Jumpponen and Trappe 1998). Enzymes of microbial origin have high biotechnological importance in the processing of food, manufacturing © The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. of detergents, pharmaceutical products and in molecular biology (Falch 1991). Extracellular enzymes are produced by ERM and DSE fungi during utilization of soil organic matter facilitating the degradation of organic substrates into simpler units. Under laboratory conditions, these extracellular enzymes are produced in liquid media and can be assayed to quantify the concentration of enzyme produced per millilitre of the filtrate, per minute. In order to assess endoglucanase production in vitro, experimental liquid medium amended with 1% CMC is often used. This mimics the natural pattern of production where hydrolysis of cellulose occurs as a result of the action of cellulolytic microorganisms in soil (Doolotkeldieva and Bobusheva 2011). Cult (...truncated)


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O. R. Adeoyo, B. I. Pletschke, J. F. Dames. Improved endoglucanase production and mycelial biomass of some ericoid fungi, AMB Express, 2017, pp. 15, Volume 7, Issue 1, DOI: 10.1186/s13568-016-0312-y