Ganoderma species are one of the most widely researched fungi because of their
reported potent bioactive properties. Although there is much information related to
American, European and Asian isolates, little research has been conducted on
Australian Ganoderma isolates. Ganoderma may only be imported into Australia under
strict quarantine conditions, therefore, the isolation of a native strain that possesses
bioactivity may be industrially and commercially significant. Three Australian species
of this wood-decomposing fungus were isolated in northern Queensland. In this study,
they have been identified as three separate species. Further, they have been studied to
determine their optimal growth conditions in liquid culture and assessed for their
antibacterial properties.
Phylogeny inferred from the Internal Transcribed Spacer Regions (ITS) from the DNA
sequences resolved the three Australian Ganoderma species into separate clades. Two
isolates were identified to be isolates of Ganoderma cupreum (H1) and Ganoderma
weberianum (H2). The third isolate could only be identified to the genus level,
Ganoderma species, due to the lack of informative data that could be used for
comparison.
The effects of short term and long term storage on the viability of the fungi were
investigated on agar plates, agar slants and balsa wood at varying temperatures ranging
from 10 to 45�C. The most appropriate storage conditions were determined to be �80�C
on balsa wood chips for periods of up to 2 years without subculture, and on agar slants
at 4�C for up to a maximum of eight weeks. Light was observed to be detrimental to the
survival of Ganoderma H1 and Ganoderma H2 during storage. Growth trials using
potato dextrose agar plates determined the optimal temperature and pH for mycelial
growth to be 30�C and a pH of 6, for all isolates. Subsequent growth trials in liquid
media found that glucose, as the carbohydrate source, supported the greatest mycelial
growth of Ganoderma H1 and Ganoderma H2 and that galactose and fructose supported
the greatest growth of Ganoderma H3.
Abstract
ii
Aqueous (hot water) and organic (hexane (HEX), dichloromethane (DCM), ethyl
acetate (EtOAc), methanol (MeOH)) extracts from the liquid cultivated mycelium were
assessed for their antibacterial activity using disc diffusion assays. Extracts from the
mycelium of Ganoderma H1 exhibited activity against a greater number of Gram
positive bacteria than those from Ganoderma H2 and H3. Subsequent studies on the
DCM and EtOAc extracts from Ganoderma H1 determined the MIC and MBC against a
number of Gram positive bacteria, including Bacillus cereus, B. subtilis, Enterococcus
faecalis, Streptococcus pyogenes, Staphylococcus aureus, S. epidermidis and Listeria
monocytogenes, as well as Clostridium species, including Clostridium perfringens, C.
sporogenes and C. difficile, and some methicillin resistant Staphylococcus aureus
(MRSA) strains. Time course growth assays confirmed that the DCM and EtOAc
extracts predominantly exhibited bactericidal activity. Finally, the active compounds
were determined to be terpenoid in structure with some phenolic groups attached.
| Identifer | oai:union.ndltd.org:ADTP/216537 |
| Date | January 2004 |
| Creators | Roberts, Lyndal, lyndalroberts@gmail.com |
| Publisher | Swinburne University of Technology. Environment and Biotechnology Centre |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.swin.edu.au/), Copyright Lyndal Roberts |
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