Sorting of microbial cell samples

Lead Research Organisation: University of Birmingham
Department Name: Sch of Biosciences


Most biological experiments investigate large numbers of cells, anything from a few hundred to many million. Experiments of this type are useful for investigating the behaviour of a group of cells. However, in many cases, it is interesting to know what individual cells are doing. One can look at an individual cell down a microscope, but this is very time-consuming if a large number of individual cells are to be studied. Machines called flow cytometers have been developed that can look at large numbers of individual cells, one at a time, in quick succession (tens of thousand per second). A flow cytometer shines a laser onto a cell and measures the light that comes out of the cell. These measurements can reveal important information about the behaviour of the cell. These instruments can also sort cells depending upon their properties and allow further study of individual cells. Previously, these instruments have been used mainly with animal cells, which are relatively large. Newer instruments allow study of smaller cells, such as bacteria. This proposal aims to purchase a flow cytometer for use with bacteria and yeasts. Many researchers will use this equipment to ask a large number of questions about the properties and behaviour of bacteria and yeast cells. Scientists in Birmingham are investigating the way in which bacteria can be used in industrial processes. Some projects look at ways of making proteins using bacteria. This is widely used in the pharmaceutical industry to make drugs such as insulin. Other projects are investigating the use of bacteria to collect metals such as gold, palladium (used in catalytic converters in cars) and uranium (from the nuclear energy industry) from industrial wastes or polluted sites. The flow cytometer will be used to better understand these processes and improve them, allowing more efficient processes to be developed. A second group of projects are looking at bacteria and yeasts that cause disease in humans. The way in which two species of bacteria that cause food poisoning survive in the human body is currently being investigated. Scientists are also working on bacteria that are resistant to antibiotics, such as MRSA, and the way in which antibiotic resistance is passed from one bacterium to another. These questions are very important to human health, as many infections are now difficult to treat with antibiotics. Another project is investigating the way a species of yeast causes disease in humans. The flow cytometer will be used to investigate new aspects of all these projects. We will answer questions about single cells that would not be possible without the instrument. The research will help us understand how bacteria and yeast cause disease and survive in the human body. The flow cytometer will be used by many researchers to answer many questions about the way bacteria and yeasts can be used to help industry and the way in which they can cause disease. It will also allow projects to be developed that link researchers from different disciplines at the University and researchers from other institutions.

Technical Summary

Most microbiological techniques rely on analysis of populations of bacteria. However, advances in flow cytometry and fluorescence-activated cell sorting (FACS) have widened the scope of single-cell analysis from mammalian cells to smaller cells and allowed the study of individual bacteria within a population. We propose to purchase a state of the art flow cytometer and cell sorter primarily for microbiological research. Flow cytometry and FACS will be utilised by several research groups in a wide range of projects within the themes of bioprocessing, gene regulation and pathogenesis. Fundamental problems facing the bioprocessing industry will be addressed, including optimisation of recombinant protein production in E. coli and microbial fermentation processes. Environmentally important bioremediation and biomineralization of toxic and precious metals, including uranium and palladium, from industrial wastes will be studied. Mechanisms of E. coli gene regulation in response to stress and heterogeneity in the transcriptional response by individual bacteria within a culture will be studied. This project is relevant to industrial applications and pathogenesis. The regulation of flagella synthesis in the foodbourne pathogen Campylobacter jejuni will also be characterised. FACS will be used to study plasmid biology, addressing the regulation of maintenance and replication of potentially medically important plasmids. In addition, antibiotic resistance mechanisms will be studied including mupirocin biosynthesis in Pseudomonas and analysis of mixed populations of multi-drug resistant bacteria. In addition to work on prokaryotes, FACS will be used to study trafficking and signalling pathways in yeast and the mechanism by which the fatal human pathogen Cryptococcus evades the host immune system. A major aim of this application is to generate interdisciplinary projects linking researchers in the bioscience, medical and engineering fields.


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