Harpreet S. Sodhi

High-Performance Liquid Chromatography Studies to Estimate Ergosterol Content at Different Developmental Stages of the Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes)

Ganoderma lucidum has been widely used as a source of potent nutraceutical products. This study was planned to identify and characterize the role of ergosterol in the developmental process of G. lucidum. Four strains of G. lucidum (GL-I-IV) showed a gradual increase in biomass (from 25.52 to 31.72 g) after 3 weeks of growth in mushroom complete medium broth, with maximum biomass observed for strain GL-III. Upon cultivation of G. lucidum strains on wheat straw supplemented with 5% wheat bran, maximum biological efficiency was recorded for the GL-I strain (31.23%), followed by GL-II (26.73%); the number of fruiting bodies were 927 and 693, each weighing 33.7 and 38.6 g, respectively. The amount of ergosterol in the Ganoderma test strains varied among the strains and at different developmental stages, namely, the vegetative mycelium, spawn run, pinhead, and fruiting body phases. The maximum ergosterol content was produced by the GL-I strain during the vegetative mycelium (4601 p.g/g) and reproductive fruiting body (7009 p.g/g) stages. However, strain GL-IV followed by strain GL-II exhibited maximum ergosterol content in the spawn run stage. The ergosterol content was better for GL-II at the pinhead stage. This report indicates that ergosterol content varies among the test strains. Moreover, it increases with each stage of the cultivation process, that is, from spawn run to pinhead to and fruiting body formation.

Selenium stress in Ganoderma lucidum: A scanning electron microscopy appraisal

The present investigation explores the effect of selenium supplementation on radial growth and ultrastructural alterations in the hyphae and spores of Ganoderma lucidum. A concentration dependent decrease in radial growth was observed on culturing G. lucidum on sodium selenate supplemented mushroom minimal agar post 24 h. However, in comparison to control, selenium supplementation slightly increased diameter of radial growth till 10 ppm after 48 h. The Scanning Electron Microscopy (SEM) studies of radial growth showed selenium concentration dependent gradual decrease in hyphal diameter suggesting thinning and extensive branching of mycelia in response to increased Se supplementation. Moreover, SE micrographs also depict selenium concentration dependent decrease in number of spores and spore size. A significant decrease in spore diameter was recorded for mushroom minimal agar supplemented with 20 and 25 ppm (5.64 and 1.26 μm, respectively) as compared to control (10.04 μm). The spore were morphologically altered from spherical to oval or oblong and inflated to constrict deformed on increasing selenium concentration. SEM-energy dispersive X-ray spectroscopy (SEM-EDS) studies of intact mycelia showed no traces of selenium. However, crushed mycelia samples exhibited Se signals probably due to presence of selenium as integral component of cytosolic moieties like selenoproteins. Atomic absorption spectroscopy (AAS) of mycelia showed an increasing trend in the uptake of selenium with increased selenium supplementation. Percentage absorption was found to be in range of 7.2 - 9.9% with maximum absorption at concentrations of 15 and 25 ppm. Hence, sodium selenate supplementation at 10 ppm (with maximum 15 ppm) can be used for Se fortification as Ganoderma can grow rapidly without significant alteration in structure and morphology to enhance its biomedicinal properties. Key words: Ganoderma, scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (SEM-EDS), selenium, selenoproteins.