Bioactivity and toxicity of polysaccharides derived from the phytopathogenic mushroom Ganoderma orbiforme cultured in...

Area of Science:

• Biotechnology
• Microbiology
• Phytopathology

Background:

• The phytopathogenic fungus G. orbiforme causes basal stem rot in oil palms, overshadowing its biotechnological applications.
• Polysaccharides, including extracellular (EPS) and intracellular (IPS) forms, are known for diverse biological activities.

Purpose of the Study:

• To investigate the growth profile of G. orbiforme in an Air-L-Shaped Bioreactor.
• To characterize the antibacterial and antioxidant properties of EPS and IPS from G. orbiforme.
• To assess the toxicity of these polysaccharides using the zebrafish embryo toxicity (ZFET) assay.

Main Methods:

• Cultivation of G. orbiforme in an Air-L-Shaped Bioreactor to determine optimal biomass and polysaccharide yield.
• Antibacterial assays (minimum inhibitory concentration) against selected pathogens.
• Antioxidant assays (DPPH and FRAP) to quantify radical scavenging and reducing power.
• Zebrafish embryo toxicity (ZFET) assay to evaluate safety and non-toxicity.

Main Results:

• Peak biomass yield of 2.53 g/L was observed, with EPS and IPS yields of 0.15 g/L and 0.06 g/L, respectively.
• EPS demonstrated broader-spectrum antibacterial activity, particularly against Streptomyces griseus and Staphylococcus epidermidis (MIC 5 mg/mL).
• Both EPS and IPS exhibited significant antioxidant activity (DPPH IC50: 15.59 mg/mL for EPS, 26.85 mg/mL for IPS) and reducing power (FRAP: ~74 mM Fe(II)/g).
• ZFET assay indicated low toxicity, with LC50 values of 1.88 mg/mL for EPS and 1.56 mg/mL for IPS, showing no developmental abnormalities in zebrafish embryos.

Conclusions:

• G. orbiforme possesses significant biotechnological potential, yielding bioactive EPS and IPS with notable antibacterial and antioxidant properties.
• The extracted polysaccharides are safe for use, as evidenced by low toxicity in the ZFET assay.
• This study supports the bioprospecting of G. orbiforme, a phytopathogen, for sustainable applications aligned with SDG 15 (Life on Land) and SDG 3 (Good Health and Well-Being).