When food goes bad: understanding biofilm formation to prevent food spoilage
Lead Research Organisation:
Quadram Institute
Department Name: Microbes in the Food Chain
Abstract
Almost 10% of the world's population do not get enough to eat. Since the global population is predicted to rise to 9.8 billion by 2050, we need to increase levels of food availability by at least 50% to be able to feed the world's population. One proposed solution has been to reduce food loss and wastage (FLW), since it is estimated that around 1/3 of the total food produced for human consumption worldwide is either lost or wasted. A major contributor to FLW is spoilage by microbes. Given these drastic numbers, many governments and global organisations are adopting a multi-pronged approach to ensure we can feed the world over the coming decades. Indeed, the importance of understanding biological processes that lead to food spoilage falls within the BBSRC's Strategic Challenge '3.2.1 Bioscience for Sustainable Agriculture and Food' and the Responsive Mode Priority of 'Reducing Waste in the Food Chain'.
Microbes (bacteria, viruses and fungi) grow on the surfaces of food, or on surfaces in the food chain, in a slimy film called a biofilm. Biofilms are found everywhere, from the slimy deposits that form on the bathroom sink, shower and fridge, to the slime seen in ponds or on rocks in nature. The slimy coating acts as a protective layer, making it very difficult to kill microbes when they are in biofilms and to physically remove the biofilm once it has formed. A major group of bacteria that cause spoilage of a range of meat, dairy and vegetable products are broadly called Pseudomonas species. When food in your fridge goes off and you throw it out, it is very likely to be due to these bacteria growing in biofilms on spoiled salad leaves, meat or on the aggregates in spoiled milk. On average 280 kg of food is lost or wasted per adult in the UK, which contributes to approx. 6.7 million tonnes, or 152,000 full lorries, of food wasted each year in the UK alone.
There are currently no strategies that directly target biofilm formation on food surfaces to either extend the shelf life of food or stop food spoilage. Overall, the work in this Fellowship aims to:
1. Determine if we can stop Pseudomonas species forming biofilms on food by targeting a common component of the slimy part of biofilms, extracellular DNA (eDNA). Many bacteria have eDNA in the biofilm slime, which provides strength and structure to the biofilm and helps the biofilm resist attempts to remove it. My preliminary data shows that there is eDNA in Pseudomonas species biofilms. I have access to an enzyme called NucB, which can break down eDNA. In this work I will test if putting NucB on food surfaces stops bacteria forming biofilms and if I can remove a biofilm that is already formed on food with NucB.
2. Understand how Pseudomonas species grow in biofilms on food to bring about food spoilage. By understanding this process in detail, we will then be able to develop new ways to stop biofilms forming on food, or on surfaces in the food chain (e.g. in food processing plants or on food packaging) to extend the shelf-life and reduce food spoilage.
This work could be directly translated into solutions to reduce the growth of bacteria on food and thus food spoilage. Additionally, the techniques developed in this Fellowship will be very useful in understanding how other bacteria, for instance those that cause food poisoning, are transmitted through the food chain.
Microbes (bacteria, viruses and fungi) grow on the surfaces of food, or on surfaces in the food chain, in a slimy film called a biofilm. Biofilms are found everywhere, from the slimy deposits that form on the bathroom sink, shower and fridge, to the slime seen in ponds or on rocks in nature. The slimy coating acts as a protective layer, making it very difficult to kill microbes when they are in biofilms and to physically remove the biofilm once it has formed. A major group of bacteria that cause spoilage of a range of meat, dairy and vegetable products are broadly called Pseudomonas species. When food in your fridge goes off and you throw it out, it is very likely to be due to these bacteria growing in biofilms on spoiled salad leaves, meat or on the aggregates in spoiled milk. On average 280 kg of food is lost or wasted per adult in the UK, which contributes to approx. 6.7 million tonnes, or 152,000 full lorries, of food wasted each year in the UK alone.
There are currently no strategies that directly target biofilm formation on food surfaces to either extend the shelf life of food or stop food spoilage. Overall, the work in this Fellowship aims to:
1. Determine if we can stop Pseudomonas species forming biofilms on food by targeting a common component of the slimy part of biofilms, extracellular DNA (eDNA). Many bacteria have eDNA in the biofilm slime, which provides strength and structure to the biofilm and helps the biofilm resist attempts to remove it. My preliminary data shows that there is eDNA in Pseudomonas species biofilms. I have access to an enzyme called NucB, which can break down eDNA. In this work I will test if putting NucB on food surfaces stops bacteria forming biofilms and if I can remove a biofilm that is already formed on food with NucB.
2. Understand how Pseudomonas species grow in biofilms on food to bring about food spoilage. By understanding this process in detail, we will then be able to develop new ways to stop biofilms forming on food, or on surfaces in the food chain (e.g. in food processing plants or on food packaging) to extend the shelf-life and reduce food spoilage.
This work could be directly translated into solutions to reduce the growth of bacteria on food and thus food spoilage. Additionally, the techniques developed in this Fellowship will be very useful in understanding how other bacteria, for instance those that cause food poisoning, are transmitted through the food chain.
Technical Summary
Almost 10% of the world's population do not get enough to eat. As the global population is predicted to rise to 9.8 billion by 2050, levels of food availability need to increase by >50%. The importance of understanding biological processes that lead to food loss through spoilage is in the BBSRC's Strategic Challenge '3.2.1 Bioscience for Sustainable Agriculture and Food' and the Responsive Mode Priority of 'Reducing Waste in the Food Chain'.
Food spoilage bacteria grow on food in 3D matrix-encased communities called biofilms. Non-pathogenic Pseudomonas species are common food spoilers however, very little is known about the mechanisms of biofilm formation and matrix composition, particularly under food chain-relevant conditions. This project will address this knowledge gap by characterising in situ biofilm formation by P. fluorescens, in 3 Objectives:
1. Identify food spoilage P. fluorescens isolates and characterise biofilm formation on chicken and lettuce.
I will develop a sophisticated imaging and analysis workflow to characterise formation of P. fluorescens biofilms in situ.
2. Characterise the role of eDNA in P. fluorescens biofilm formation on chicken and lettuce and explore the use of DNase to target biofilms in situ
I will determine if and where eDNA is present in P. fluorescens biofilms in situ and if a thermostable DNase can inhibit de novo biofilm formation and/or eradicate biofilms. Live biofilms on food will be imaged with sophisticated fluorescence microscopy.
3. Identify the genes involved in P. fluorescens biofilm formation on chicken and lettuce. I will use genomics and transcriptomics to identify genes involved in P. fluorescens biofilm development in situ. I will then use seq-fluorescence in situ hybridisation (seq-FISH), to visualise where and when key genes for biofilm formation are expressed during biofilm formation on food. I will also use functional genomics to further characterise their role in biofilm development.
Food spoilage bacteria grow on food in 3D matrix-encased communities called biofilms. Non-pathogenic Pseudomonas species are common food spoilers however, very little is known about the mechanisms of biofilm formation and matrix composition, particularly under food chain-relevant conditions. This project will address this knowledge gap by characterising in situ biofilm formation by P. fluorescens, in 3 Objectives:
1. Identify food spoilage P. fluorescens isolates and characterise biofilm formation on chicken and lettuce.
I will develop a sophisticated imaging and analysis workflow to characterise formation of P. fluorescens biofilms in situ.
2. Characterise the role of eDNA in P. fluorescens biofilm formation on chicken and lettuce and explore the use of DNase to target biofilms in situ
I will determine if and where eDNA is present in P. fluorescens biofilms in situ and if a thermostable DNase can inhibit de novo biofilm formation and/or eradicate biofilms. Live biofilms on food will be imaged with sophisticated fluorescence microscopy.
3. Identify the genes involved in P. fluorescens biofilm formation on chicken and lettuce. I will use genomics and transcriptomics to identify genes involved in P. fluorescens biofilm development in situ. I will then use seq-fluorescence in situ hybridisation (seq-FISH), to visualise where and when key genes for biofilm formation are expressed during biofilm formation on food. I will also use functional genomics to further characterise their role in biofilm development.
