NMR fingerprints, an integrated approach to uncover the unique components of the drug-like natural product metabolome of termite gut-associated Streptomyces species

A new NMR-based method to access to the unique components of the drug-like natural product metabolome of termite-gut associatedStreptomyces strainshas been developed.

Detection of thermoactinomyces species in selected agricultural substrates from Queensland

Selected overheated substrates commercially available for public use in sub-tropical Queensland, Australia were screened for the presence of Thermoactinomyces species using an air sampler. All substrates with the exception of tea tree mulch were found to contain Thermoactinomyces species. Subsequent 16S rDNA oligonucleotide sequencing of the selected eight isolates indicated that some of these species were closely related to previously reported allergenic Thermoactinomyces vulgaris and Laceyella sacchari. In view of this, the isolates were tested to determine their adhesion ability and cytotoxicity to human lung cells (calu-3 cells). The results indicated that all eight isolates were highly adherent and showed cytotoxicity to this cell line. These findings might indicate that the presence of such species in overheated agricultural materials may constitute a public health risk if storage and handling conditions are not optimal and do not meet criteria defined for sub-tropical climates.

Actinobacterial resources from termite guts for regional bioindustries

The State government of Queensland launched a well-funded 10 year strategy for bioindustry development in 1999 with the aim of making Queensland the Asia-Pacific hub of biotechnology. This strategic approach into diversifying the region?s economic base through the development of knowledge industries has rapidly transformed traditional methods to cutting edge technologies utilised for bioindustry. Microbially mediated technologies have thus gained importance for the production of biofuels and bioproducts, bioenvironmental management of natural resources, bioremediation, waste and wastewater management.

Use of phage battery to investigate the actinofloral layers of termite gut microflora

AIMS

The termite gut microbiota can include a variety of micro-organisms from the three domains: Bacteria, Archaea and Eucarya. The bacterial groups from the gut systems are mainly affiliated to the proteobacteria, the Gram-positive groups Bacterioiodes/Flavobacterium branch and the spirochetes, Firmicutes and Actinobacteria. However, culture independent molecular studies have revealed that the majority of these microbial gut symbionts have not yet been cultured, including actinobacterial clusters associated with termite guts. Accordingly, the aim of this study was to selectively isolate the actinofloral layers of gut associated microflora of the Coptotermes lacteus (Froggatt) species located at the Sunshine Coast Region of Queensland, Australia to increase our knowledge on the diversity of actinobacterial taxa present in the termite guts.

METHODS AND RESULTS

Actinofloral layers associated with the guts of the wood-eating subterranean termite C. lacteus were investigated by exploiting the phage susceptibility of different gut associated bacteria which impede the growth of actinomycetes on isolation plates. These unwanted microbial taxa were removed by exposing the gut contents to polyvalent bacteriophages specifically targeting different background bacterial taxa and after their removal from the isolation plates previously undetected and novel actinomycetes were successfully cultured from the gut samples.

CONCLUSIONS

Use of bacteriophages as a means of selective pressure successfully revealed the presence of novel actinomycete species within the guts of C. lacteus.

SIGNIFICANCE AND IMPACT OF THE STUDY

Molecular ecology has undoubtedly revealed the fascinating diversity of micro-organisms, which cannot be cultured. However, these advances in the field still have not provided the ability to detect and isolate micro-organisms effectively from their ecological niches. Accordingly, studies like the one described here have importance in increasing the chances of uncultured taxa to be isolated to complement molecular microbial ecological efforts towards the establishment of an understanding on the diversity of termite gut microflora.

Mesophilic Actinomycetes in the natural and reconstructed sand dune vegetation zones of Fraser Island, Australia

The natural coastal habitat of Fraser Island located in the State of Queensland, Australia, has been disturbed in the past for mining of the mineral sand ilmenite. Currently, there is no information available on whether these past mining disturbances have affected the distribution, diversity, and survival of beneficial soil microorganisms in the sand dunes of the island. This in turn could deleteriously affect the success of the natural regeneration, plant growth, and establishment on the sand dunes. To support ongoing restoration efforts at sites like these mesophilic actinomycetes were isolated using conventional techniques, with particular emphasis on the taxa previously reported to produce plant-growth-promoting substances and providing support to mycorrhizal fungi, were studied at disturbed sites and compared with natural sites. In the natural sites, foredunes contained higher densities of micromonosporae replaced by increasing numbers of streptomycete species in the successional dune and finally leading to complex actinomycete communities in the mature hind dunes. Whereas in the disturbed zones affected by previous mining activities, which are currently being rehabilitated, no culturable actinomycete communities were detected. These findings suggest that the paucity of beneficial microflora in the rehabilitated sand dunes may be limiting the successful colonization by pioneer plant species. Failure to establish a cover of plant species would result in the mature hind dune plants being exposed to harsh salt and climatic conditions. This could exacerbate the incidence of wind erosion, resulting in the destabilization of well-defined and vegetated successional dunal zones.

Fighting foam with phages?

Seventeen (17) phages infective for the mycolata were isolated from six samples of activated sludge using 21 prospective hosts from the genera Dietzia, Gordonia, Nocardia, Rhodococcus, Tsukamurella and Mycobacterium. Their morphology indicated that they were all members of the viral family Siphoviridae, but they varied in the size of the icosahedral head and length of non-contractile tail, suggesting they were different. This was confirmed by host-range studies with 47 strains of mycolata, which showed that each phage had a unique host-range, and this was polyvalent in the majority (15/17) of cases, with 12 phages infective for hosts representing two or three of the genera Gordonia, Nocardia and Rhodococcus. The potential for use of these phages in the control of foaming and other applications is discussed.

Isolation of Dermatophilus congolensis phage from the 'lumpy wool' of sheep in Western Australia

A lytic phage with species-specific activity was isolated from wool samples infected with the actinomycete Dermatophilus congolensis, the agent of 'lumpy wool', collected from properties in Western Australia. The physiochemical properties, plaque morphology, host range and particle morphology of the phage isolated were characterized. The isolated phage reduced the cell numbers of Dermatophilus congolensis on infected wool samples in vitro. It may therefore have potential as a biocontrol agent of dermatophilosis.

Possible roles of competition for thiamine, production of inhibitory compounds, and hyphal interactions in suppression of the take-all fungus by a sterile red fungus

Possible mechanisms involved in the suppression of the take-all fungus (Gaeumannomyces graminis var. tritici) by a sterile red fungus were examined. Studies on the effects of foliar application of thiamine to plants showed a reduction in take-all suppression by the sterile red fungus thereby indicating that competition for this particular vitamin, required by both fungi, could be one of the mechanisms of antagonism. Treatment with the exudate produced by the sterile red fungus on solid substrates resulted in lysis of the hyphae of the take-all fungus. Exudate produced on sterilised wheat seeds was more inhibitory to the take-all fungus than that produced on ryegrass seeds. Fungal inhibition increased as the duration of exposure to the exudate increased. The primary effects of hyphal interactions between the sterile red fungus and the take-all fungus were evident as coiling and contact lysis. It is possible that a combination of mechanisms including the above may be involved in suppression of the take-all fungus by the sterile red fungus.Key words: take-all suppression, sterile red fungus.

Detection and identification of novel actinomycetes

The actinomycetes are well known as a group of filamentous, Gram-positive bacteria that produce many useful secondary metabolites, including antibiotics and enzymes. Although they have been intensively studied for both theoretical and practical objectives, there is much scope for developing our basic knowledge of the means of detection and isolation of these microbes. This session concentrated on new methods for the detection and identification of novel actinomycetes from a range of environments. Approaches to the detection of actinomycetes ranged from investigations of neglected habitats and extreme environments (e.g. alkaline soils and oil drills) to the analysis of DNA extracted from the environment and use of specific phages. The continuing problems of the identification of actinomycete isolates were also considered. Topics discussed included use of phage typing, DNA probes, and correlation between phenetic and genotypic species of Streptomyces.

Occurrence of Actinomadura phage in organic mulches used for avocado plantations in Western Australia

Phage infecting Actinomadura verrucosospora, Actinomadura pusilla, and Nocardiopsis flava were isolated from mulches applied to avocado trees at the University of Western Australia experimental plots. The physiochemical properties, plaque morphology, host range, and particle morphology of the phage isolated are described. Taxonomic implications of the reactions of some cell wall chemotype III actinomycetes to Actinomadura phage are also discussed.Key words: Actinomadura phage.

Use of bacteriophage for the selective isolation of thermophilic actinomycetes from composted eucalyptus bark

A method was developed to reduce the numbers of thermophilic bacteria on isolation plates, which in turn facilitated the detection and isolation of thermophilic actinomycetes. The method involves exposing the test material to bacteriophage suspensions prior to inoculation on isolation plates. This method was applied to composted eucalyptus bark samples, which were then inoculated on R8 and 1/2 TSA + 0.2% casein hydrolysate agar plates. The phage susceptibility of thermophilic bacteria provided a selective means of reducing their numbers on isolation plates and hence increased the numbers of Thermomonospora, Saccharopolyspora rectivirgula, and thermophilic Streptomyces spp. on these media in comparison with the numbers recorded from control plates.

Use of polyvalent phage for reduction of streptomycetes on soil dilution plates

An isolation method was developed in which prior to inoculation soil suspensions were exposed to suspensions of polyvalent phage isolated to Streptomyces spp. The phage susceptibility of streptomycetes provided a selective means of reducing streptomycetes on isolation plates subsequent to inoculation, and this reduction was persistent after long incubation periods. The efficiency and applicability of the method developed were checked with different samples from a range of sources. The increased chances of development of other genera after the reduction of streptomycetes on soil dilution plates were assessed.