The Occurrence of Bioactive Micromonosporae in Aquatic Habitats of the Sunshine Coast in Australia

Screening strategies based on the ecological knowledge of antibiotic producing microorganisms and their roles in the natural environment are being increasingly employed in the search for novel antibiotic agents. Micromonosporae are common inhabitants of aquatic habitats and have proved to be a continuing source of novel bioactive compounds including antibacterial and antitumor agents. The ecological distribution and frequency of bioactive micromonosporae in Sunshine Coast region aquatic habitats were studied through a range of selective isolation procedures designed to negatively select against the isolation of unwanted microbial taxa commonly associated with marine environments. It was revealed that bioactive compound producing species of micromonosporae were present in the aquatic habitats of the Sunshine Coast region in Australia

Streptophage-mediated control of off-flavour taint producing streptomycetes isolated from barramundi ponds

Off-flavour taint of aquaculture products is a global issue reducing consumer confidence in the farmed produce as they are taken up via the gills of fish, and deposited in the lipids of the animal. If the fish are not purged, resulting undesirable muddy earthy flavour taint can be tasted by consumers. These undesirable flavour and odour is caused by the terpenoid compounds namely geosmin and 2-methylisoborneol, produced as secondary metabolites by certain bacteria including the cyanobacteria and actinomycetes. Current strategies to remediate the problem rely on treating the symptoms not the cause and involve the use of time consuming purging methods and costly chemicals. Biological control using bacteriophages, specific to the problem causing bacteria, offers a natural alternative to chemical control, which might reduce further complications of copper based algaecides and its subsequent implications on water quality. In an adaptation of such biological control approach streptomycetes isolated from barramundi ponds were tested for their susceptibility to streptophages to understand whether host destruction via phage lysis would subsequently eliminate off-flavour taint productions by these isolates. Following the determination of the streptophage susceptibility of the isolates one of the most odourous streptomycete species (USC-14510) was selected to be tested further using different pond simulations resembling real-life applications. Geosmin was tested as the indicator of off-flavour taint production and as it has been previously reported that the cyanobacteria-actinomycete interactions occurring in ponds result in even greater levels of geosmin and 2-methylisoborneol, the geosmin levels for the isolate in the presence of cyanobacteria and streptophages were also tested. Findings indicated that the highly odourous Streptomyces species (USC-14510) once infected with streptophages, can lose its capacity to produce off-flavour taints. Pond simulation studies also revealed geosmin production was significantly reduced when streptophages were introduced into the pond water where streptomycete species were grown. The bacteriophage control method developed in the presented study might again confirm significant potential for the bacteriophage-mediated remediation strategy to be adapted by the aquaculture industry

Detecting co-cultivation induced chemical diversity via 2D NMR fingerprints

Rediscovery of already known compounds is a major issue in microbial natural product drug discovery. In recent years, progress has been made in developing more efficient analytical approaches that quickly identify known compounds in a sample to minimise rediscovery. In parallel, whole genome sequencing of microorganisms has revealed their immense potential to produce secondary metabolites, yet the majority of biosynthetic genes remain silent under common laboratory culturing conditions. Therefore, increased research has focused on optimising culturing methods to activate the silent biosynthetic gene clusters. Co-cultivation of different microbial strains can activate biosynthetic gene clusters that remain silent under standard laboratory fermentations involving monocultures, hence, the technique has great potential for natural product drug discovery. However, innovative methods are still needed to evaluate the success of any cocultured fermentation end-product. Here, the application of HSQC-TOCSY NMR spectra and subsequent PCoA to identify changes in the metabolite diversity induced through co-cultivation is described

Taxonomy of prokaryotic viruses : 2018-2019 update from the ICTV Bacterial and Archaeal Viruses Subcommittee

This article is a summary of the activities of the ICTV's Bacterial and Archaeal Viruses Subcommittee for the years 2018 and 2019. Highlights include the creation of a new order, 10 families, 22 subfamilies, 424 genera and 964 species. Some of our concerns about the ICTV's ability to adjust to and incorporate new DNA- and protein-based taxonomic tools are discussed.Peer reviewe

The global catalogue of microorganisms 10K type strain sequencing project: closing the genomic gaps for the validly published prokaryotic and fungi species

Genomic information is essential for taxonomic, phylogenetic and functional studies to comprehensively decipher the characteristics of microorganisms, to explore microbiomes through metagenomics, and to answer fundamental questions of nature and human life. However, large gaps remain in the available genomic sequencing information published for bacterial and archaeal species, and the gaps are even larger for fungal type strains. The Global Catalogue of Microorganisms (GCM) leads an internationally coordinated effort to sequence type strains and close gaps in the genomic maps of microbes. Hence, the GCM aims to promote research by deep-mining genomic data.This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant XDA19050301), the Bureau of International Cooperation of the Chinese Academy of Sciences (grants 153211KYSB20160029 and 153211KYSB20150010), the National Key Research Program of China (grants 2017YFC1201202, 2016YFC1201303, and 2016YFC0901702), the 13th Five-year Informatization Plan of the Chinese Academy of Sciences (grant XXH13506), and the National Science Foundation for Young Scientists of China (grant 31701157).info:eu-repo/semantics/publishedVersio

Screening of Oomycete Fungi for Their Potential Role in Reducing the Biting Midge (Diptera: Ceratopogonidae) Larval Populations in Hervey Bay, Queensland, Australia

Biting midges are globally distributed pests causing significant economic losses and transmitting arbovirus diseases to both animals and humans. Current biological and chemical control strategies for biting midge target destruction of adult forms, but strategies directed at immature stages of the insect have yet to be explored in Australia. In the present study, coastal waters of Hervey Bay region in Queensland, Australia were screened to detect the habitats of biting midge at immature stages. These results were then correlated to local environmental conditions and naturally occurring entomopathogenic fungal flora, in particular the Oomycete fungi, to determine their reducing effect on insect immature stages in the search for biological control agents in the region. The dominant species of biting midge found within this study was Culicoides subimmaculatus occuring between mean high water neaps and mean high water spring tide levels. Within this intertidal zone, the presence of C. subimmaculatus larvae was found to be influenced by both sediment size and distance from shore. Halophytophthora isolates colonized both dead and alive pupae. However, the association was found to be surface colonization rather than invasion causing the death of the host. Lack of aggressive oomycete fungal antagonists towards midge larvae might correlate with increased incidences of biting midge infestations in the region

Use of bacteriophages as biological control agents in horticulture

Bacterial diseases in horticultural settings or infestation of fresh produce with human pathogenic bacteria can constitute a serious public health risk. To control horticultural bacterial diseases, chemical control strategies have traditionally been used, such as the application of bactericides and copper-based products, which resulted in development of resistance in bacteria against these agents. Moreover, the use of such chemical preventative measures on fresh produce can detrimentally affect human, animal and ecosystem health. Bacteriophages have been used to control pathogenic bacteria since the 1920s due to their specificity against host bacteria, as well as their ability to survive and infect their host without detrimental effects to the surrounding environments. As a result, their targeted host specific applications in horticultural settings can be of interest to growers as well as to the consumers. In this laboratory report, the efficacy of a bacteriophage cocktail when applied to fresh herbs inoculated with Escherichia coli was determined. Significant (P ≤ 0.001) reductions in E. coli colony forming units were observed in phage treated herb samples compared to counts in the control. These findings suggest that bacteriophage present as an alternative biocontrol for E. coli in horticulture

Assessment of the Role of Local Strawberry Rhizosphere—Associated Streptomycetes on the Bacterially—Induced Growth and Botrytis cinerea Infection Resistance of the Fruit

The future need for sustainable agriculture will be met in part by wider use of biological control of plant pathogens over conventional fungicides hazardous to the environment and to public health. Control strategies involving both (i) direct use of microorganisms antagonistic to the phytopathogen, and (ii) use of bioactive compounds (secondary metabolites/antibiotic compounds) from microorganisms on the phytopathogen were both adapted in order to investigate the ability of streptomycetes isolated from the rhizosphere of strawberry plants to promote the growth of the fruit and suppress Botrytis cinerea causing strawberry rot on the Sunshine Coast, Queensland, Australia. In vitro studies showed that 25/39 streptomycetes isolated from strawberry field soils inhibited B. cinerea growth by antifungal activity, ranging from antibiosis to volatile compound production. However, when non-volatile antifungal compounds were extracted and applied aerially to the actively growing strawberry fruits infected with B. cinerea, a significant disease reduction was not recorded. On the other hand, plant and fruit growth was promoted by the presence of actively growing streptomycetes in container media. Findings might indicate that live streptomycete inoculum can be used as growth promoting agent in container media for this economically important crop.strawberry; Botrytis cinerea ; streptomycetes; biological control; growth promotion

Taxonomic and Metabolite Diversity of Actinomycetes Associated with Three Australian Ascidians

Actinomycetes are known to be the most prolific producers of biologically active metabolites. Here, we investigated the host species-specificity and the related secondary metabolites of actinomycetes that are associated with three different Australian ascidians, namely Symplegma rubra, Aplidium solidum, and Polyclinum vasculosum. Results indicated that while isolates from the genera Streptomyces and Micromonospora were highly diverse in the ascidian samples, only two culturable actinomycete Operational Taxonomic Units (OTUs) overlapped between all of the ascidians, pointing to some degree of host species-specificity of the isolates and selective acquisition of microbial associates by the host from the surrounding environment. LC-MS/MS profiling of extracts obtained from the ascidians and their actinomycete associates revealed many overlapping ions between hosts and actinomycetes, indicating that these compounds were likely to be synthesised by the microbial associates. Laboratory cultures of the actinomycetes displayed even more diverse metabolomes than those of their ascidian hosts; thus, making ascidian-associated actinomycetes an excellent target for natural product drug discovery and biotechnology