Bioactive volatile compounds of some new fungi endemic to Thailand and endophytic fungi Isolated from Schefflera leucantha and Barleria prionitis

Name: Sarunpron Khruengsai

keyword: Bioactivity

MeSH: Biodegradation -- 300246

Classification :.DDC: e-Theses

; Biocontrol

MeSH: Bioactive compounds -- 300247

MeSH: Endophytic fungi -- 61662

MeSH: Fumigation -- 300248

MeSH: Fungi -- Biotechnology -- 300249

LCSH: Biodegradation -- 300246

LCSH: Bioactive compounds -- 300247

LCSH: Endophytic fungi -- 61662

LCSH: Fumigation -- 300248

LCSH: Fungi -- Biotechnology -- 300249

Abstract: This research aimed to investigate the secondary metabolites and biological activities derived from some new fungi endemic to Thailand, Schefflera leucantha, and Barleria prionitis. Two Fusarium fungi, F. oxysporum and F. proliferatum, have been recognized as major pathogenic fungi that cause post-harvest decay of chili fruits. Ozone and some toxic chemicals are used to control pathogenic infections, leading to longer storage lives of agricultural commodities. However, these chemicals may pose some risks to the applicators and the environment. Therefore, alternative, easy-to-use fumigants for effective control of Fusarium infections in harvested fresh chilies are needed. Two endophytic fungi, Trichoderma afroharzianum strain MFLUCC19-0090 and T. afroharzianum strain MFLUCC19-0091, were isolated from Schefflera leucantha leaves. Their volatile compounds were investigated for antifungal activities against Fusarium oxysporum and F. proliferatum, which cause significant rot in fresh chilies. In vitro results showed that the volatile compounds produced by each strain inhibited pathogen growth. Additionally, the Trichoderma-derived volatile compounds significantly reduced Fusarium-related disease severity and incidence percentages in the inoculated fresh chilies. Antifungal properties of the volatile compounds were found to be specific to the species of the tested pathogens (MFLUCC19-0090 greatly suppressed F. oxysporum and MFLUCC19-0091 greatly suppressed F. proliferatum). Seventy-three volatile compounds were detected from both strains. Among the major volatile compounds detected, phenyl ethyl alcohol was found to possess the strongest antifungal activity against both pathogens. These Trichoderma-derived volatile compounds may be applied as alternative fumigants for controlling Fusarium rot in harvested fresh chilies. The successful use of volatile compounds as biofumigants can prevent significant market losses and, more importantly, may reduce the health hazards caused by Fusarium-associated mycotoxin exposures among consumers. Fungal endophytes are microorganisms living symbiotically with a host plant. They can produce volatile compounds that have antimicrobial activity. This study aimed to isolate endophytic fungi from Barleria prionitis plants grown in Thailand and to investigate the antifungal properties of their volatile compounds against Colletotrichum acutatum, a causal agent of anthracnose disease on post-harvest strawberry fruits. A total of 34 endophytic fungi were isolated from leaves of B. prionitis. The volatile compounds produced from each individual isolate were screened for their antifungal activity against C. acutatum using a dual-culture plate method. From this in vitro screening experiment, the volatile compounds produced by the endophytic isolate BP11 were found to have the highest inhibition percentage (80.3%) against the mycelial growth of C. acutatum. The endophytic isolate BP11 was molecularly identified as Daldinia eschscholtzii MFLUCC 19-0493. This strain was then selected for an in vivo experiment. Results from the in vivo experiment indicated that the volatile compounds produced by D. eschscholtzii MFLUCC 19-0493 were able to inhibit infections by C. acutatum on organic fresh strawberry fruits with an inhibition percentage of 72.4%. The quality of the pathogen-inoculated strawberry fruits treated with volatile compounds produced by D. eschscholtzii MFLUCC 19-0493 was evaluated. Their fruit firmness, total soluble solids, and pH were found to be similar to the untreated strawberry fruits. Solid phase microextraction-gas chromatographic-mass spectrometric analysis of the volatile compounds produced by D. eschscholtzii MFLUCC 19-0493 led to the detection and identification of 60 compounds. The major compounds were elemicin (23.8%), benzaldehyde dimethyl acetal (8.5%), ethyl sorbate (6.8%), methyl geranate (6.5%), trans-sabinene hydrate (5.4%), and 3,5-dimethyl-4-heptanone (5.1%). Each was tested for its antifungal activity against C. acutatum using the in vitro assay. While all these selected volatile compounds showed varying degrees of antifungal activity, elemicin was found to possess the strongest antifungal activity. This work suggests that D. eschscholtzii MFLUCC 19-0493 could be a promising natural preservative for controlling C. acutatum associated anthracnose disease in strawberry fruits during the post-harvest period. Accumulated plastic waste in the environment is a serious problem that poses an ecological threat. Plastic waste has been reduced by initiating and applying different alternative methods from several perspectives, including fungal treatment. Biodegradation of 30 fungi from Thailand were screened in mineral salt medium agar containing low-density polyethylene (LDPE) films. Diaporthe italiana, Thyrostroma jaczewskii, Collectotrichum fructicola, and Stagonosporopsis citrulli were found to grow significantly by culturing with LDPE film as the only sole carbon source compared to those obtained from Aspergillus niger. These fungi were further cultured in mineral salt medium broth containing LDPE film as the sole carbon source for 90 days. The biodegradation ability of these fungi was evaluated from the amount of CO2 and enzyme production. Different amounts of CO2 were released from D. italiana, T. jaczewskii, C. fructicola, S. citrulli, and A. niger culturing with LDPE film, ranging from 0.45 to 1.45, 0.36 to 1.22, 0.45 to 1.45, 0.33 to 1.26, and 0.37 to 1.27 g/L, respectively. These fungi were able to secrete a large amount of laccase enzyme compared to manganese peroxidase, and lignin peroxidase enzymes detected under the same conditions. The degradation of LDPE films by culturing with these fungi was further determined. LDPE films cultured with D. italiana, T. jaczewskii, C. fructicola, S. citrulli, and A. niger showed weight loss of 43.90%, 46.34% 48.78%, 45.12%, and 28.78%, respectively. The tensile strength of LDPE films cultured with D. italiana, T. jaczewskii, C. fructicola, S. citrulli, and A. niger also reduced significantly by 1.56, 1.78, 0.43, 1.86, and 3.34 MPa, respectively. The results from Fourier transform infrared spectroscopy (FTIR) reveal an increasing carbonyl index in LDPE films culturing with these fungi, especially C. fructicola. Analysis of LDPE films using scanning electron microscopy (SEM) confirmed the biodegradation by the presence of morphological changes such as cracks, scions, and holes on the surface of the film. The volatile compounds emitted from LDPE films cultured with these fungi were analyzed by gas chromatography-mass spectrometry. Volatile compounds such as 1,3-dimethoxy-benzene, 1,3-dimethoxy-5-(1-methylethyl)-benzene, and 1,1-dimethoxy-decane were detected among these fungi. Overall, these fungi have the ability to break down and consume the LDPE film. The fungus C. fructicola is a promising resource for the biodegradation of LDPE which may be further applied in plastic degradation systems based on fungi. Polyester urethanes (PUR) are widely used in industries and have led to a worldwide plastic waste problem. Thus, novel solutions for PUR degradation are required to reduce environmental pollution. This work investigates the PUR biodegradation efficiency of 34 fungal species using a polyester-polyurethane colloid branded Impranil DLN (Impranil) compared to Aspergillus niger, which served as the positive control. The biodegradation is evaluated based on its ability to clear Impranil in media. Eleven fungi can clear Impranil in both solid- and liquid-medium assays. The highest degradation was attributed to Embarria clematidis cultured with Impranil as a carbon source. The degradation was confirmed by the Sturm test, FTIR spectroscopy, and GC-MS. From the Sturm test, CO2 at a concentration of 0.85 g/L was found in E. clematidis cultured with 150 mL of Impranil solution after a 2-week incubation period while the CO2 at a concentration of 0.53 g/L was detected from A. niger in the same conditions. The biodegradation was further confirmed by evaluating the clearance percentage of supernatant of E. clematidis and A. niger culturing with Impranil from the Sturm test. The clearance percentage of E. clematidis and A. niger supernatant was 88.84% and 48.97%, respectively. Moreover, the degradation of soft segment and breakdown of ester linkages were observed, as evidenced by the decrease of the carbonyl (1715 cm-1) and N-H stretching (1340 cm-1 and 1020 cm-1) FTIR spectral peaks, respectively. GC-MS detected 5Z-octenol, 2E,4E-hexadienol acetate, 3Z-hexenyl isobutanoate, phenyl-tert-butanol, and 3E,6Z-nonadienol as degradation products from the E. clematidis culture in Impranil with higher intensity than those observed in Impranil liquid medium without the fungi culture. The fungus was screened for its ability to produce extracellular esterase, protease, and urease enzymes. Extracellular esterase, very low urease, and no protease activities were detected in the culture supernatant of E. clematidis in the presence of Impranil. E. clematidis can degrade Impranil partially via hydrolysis of ester linkages by cell-bound esterases at a considerable rate without any prior treatment. This fungus not only degraded Impranil but also mineralized them into CO2 and H2O. E. clematidis can be applied in the process of biochemical depolymerization of PUR for the pure monomers recycling.

Mae Fah Luang University. Learning Resources and Educational Media Center

Address: CHIANG RAI

Email: library@mfu.ac.th

Name: Patcharee Pripdeevech

Role: Advisor

Created: 2022

Modified: 2023-04-05

Issued: 2023-04-05

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: e-Theses

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Applied Chemistry

Grantor: Mae Fah Luang University

©copyrights Mae Fah Luang University

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