An important part of the SafeFish remit is to build capability in food safety and market access for the Australian seafood industry. To assist with this, SafeFish offers post-graduate grant and summer student placement opportunities to encourage blue sky and/or applied research projects around priority issues on the SafeFish agenda, whilst simultaneously building our researchers of the future.

Post-graduate Students

A $10,000 pa supplementary grant is available to Australian post-graduate students undertaking a research project relating to food safety or market access of Australian seafood. Example research areas include contamination of any hazard (microbial, chemical or physical) in seafood either produced or imported into Australia, public health aspects, risk assessment, risk management or risk communication, supply chain/processing activities that impact food safety, traceability, seafood fraud related to food safety, or other high priority topics deemed acceptable to the SafeFish partnership. Applicants may apply for access to the grant for one to three years.

In January 2023 a notice for the grant was sent to 43 Australian Universities and sent directly to relevant researchers/consultants. There were 6 applications received which included research focusses on ciguatoxins, climate change, biotoxins, food safety and vibrios (2). There were two successful candidate selected for the 2023 period, these were Ms. Madeline Petrusic from Swinburne University of Technology and Felipe Hernan Henriquez from the University of Technology Sydney.

The SafeFish post-graduate grant will be made available again for the 2024 period. Interested applicants should contact the secretariat for more information.

2023 Successful applicants:

Madeline Petrusic, Swinburne University of Technology

Bacteriophage biocontrol for Vibrios in Oysters

To meet increasing consumer demand, Australia’s rapidly growing aquaculture industry must develop new and innovative ways of ensuring safe and sustainable seafood. Vibrio parahaemolyticus, which occurs naturally in warm coastal waters, is a key concern for oyster growers. Oysters and other bivalve shellfish are filter-feeders and may concentrate bacteria from the surrounding water in their digestive systems. As most people consume oysters raw, V. parahaemolyticus contamination poses a high risk of illness. Although outbreaks of vibriosis in Australia have been historically rare, they are increasing in frequency due to rising ocean temperatures.

Current measures for controlling V. parahaemolyticus contamination in oysters include depuration and rapid cooling to limit bacterial growth during transport and storage. However, given the increased risk of V. parahaemolyticus contamination due to climate change, additional or alternative approaches are needed to combat this problem. One potential approach is bacteriophage biocontrol. Bacteriophages are highly host-specific viruses that infect bacteria. Bacteriophage biocontrol is a method which involves the application of virulent bacteriophages to foods to destroy specific pathogens of concern. Commercial bacteriophage products have been developed to inhibit Listeria monocytogenes and Escherichia coli in processed foods, and many others are in development. However, to date, there has been limited research into their potential use in oysters. A key advantage of bacteriophage biocontrol when compared to thermal or chemical control measures is that it does not affect the organoleptic properties of the food. This is an important consideration for oysters, which have a delicate flavour and texture.

This PhD project aims to explore the potential of bacteriophages to control V. parahaemolyticus during oyster production. To achieve this aim, two Vibrio-specific bacteriophages provided by the Australian Crayfish Hatchery will be assessed to determine their suitability as biocontrol candidates for food safety applications. This will involve biological characterisation, including morphological examination, host range studies, growth curve assays, and stability studies. In addition, whole genome sequencing will be performed to confirm the absence of transferable toxigenic and antibiotic resistance traits. Following this assessment, the bacteriophages will be subjected to conditions present during food production stages to determine the effects on infectivity and the optimum conditions for application. This will include testing the effects of temperature, pH, UV, chlorination and salinity on bacteriophage infectivity. The final phase of the project will involve testing the ability of the bacteriophages to inhibit V. parahaemolyticus in oysters. This will involve testing the ability of the bacteriophages to destroy V. parahaemolyticus in live oysters in a laboratory-scale depuration system under various conditions to mimic depuration systems used during harvesting.

The findings from this project will contribute to our understanding of how bacteriophage biocontrol may be used to disinfect oysters through the various stages of “farm-to-fork” production. If bacteriophages are proven to be an effective method of controlling V. parahaemolyticus in oysters, they can be developed into natural food preservatives. As a natural food preservative, bacteriophages can be used during harvesting, processing, handling and storage in the shellfish industry.

Felipe Hernan Henriquez, University of Technology, Sydney

Monitoring for food safety in the shellfish industry

Global bivalve production has significantly grown over the past decades, with approximately 90% of the produce coming from aquaculture. In this context, the occurrence of harmful algal blooms (HABs) represents a significant and ongoing issue for the shellfish industry (especially of the filter-feeders), as some species of microalgae naturally produce marine biotoxins that can prevail in the water column and enter the food web, causing sicknesses and/or death of higher trophic organisms that consume them, including humans.

Currently, morphotype-based identification methods such as microscopy, are traditionally the standard monitoring tool to assess and manage regional ecosystems for the potential of HABs. However, it can be difficult to identify very small species, species that are misshapen due to the use of cell-fixing agents, and cryptic species. This is the case with some species of the former Alexandrium tamarense species complex, which are highly cryptic. Similarly, for many species within the diatom genus Pseudo-nitzschia, it is difficult to distinguish to species level without confirmatory molecular analyses. Other disadvantages of the current methods include difficulties with the logistics, such as transportation and cold-chain requirements, and the need of specialized laboratories, expensive reagents and equipment, and often time-consuming processing of the samples. Molecular genetic techniques that can be implemented in an aquaculture setting as rapid management tools, such as a multiplex qPCR assays to detect multiple HAB species in one assay, have the potential to be a feasible method for routine monitoring for seafood safety, giving comparable results to those of microscopy-based methods for analysing HAB abundance and distribution.

The aim of the present project is to develop and test a multiplex qPCR assay that can simultaneously detect Dinophysis species that produce Diarrhetic Shellfish Toxins (DST), a gene involved in Paralytic Shellfish Toxins (PST) biosynthesis (sxtA), and certain clade of Pseudo-nitzschia species that produce Amnesic Shellfish Toxins (AST). To achieve this aim, specific primers and probes were designed for a novel qPCR assay for the detection of Dinophysis species. Later, specificity, sensitivity, and efficiency of this multiplex qPCR assay aiming three different targets (ASP, DSP, and PSP) was tested in laboratory conditions with satisfactory results. Following this assessment, further evaluation of this multiplex qPCR assay with environmental samples is needed. The final stage of this project will consist in comparing qPCR results with current monitoring methods such as microscopy and biotoxin testing of shellfish flesh to evaluate the feasibility of the use of both methods to better understand HABs development, and act as an early warning monitoring system for food safety.

The development of this novel multiplex qPCR assay has the potential to provide a rapid, portable, low cost, and potentially automatised tool that can be used on farm, with data made available on-site, to develop an early warning system for managing HABs with specific application to the aquaculture shellfish industry.

Summer Students

To assist with building capability and understanding in seafood food safety in Australia, SafeFish also have the capacity to offer two 4-week summer placement opportunities per year to assist with delivering components of the SafeFish work program. For more information, please contact the Secretariat for more information.