Utilizing microarrays of bacterial genes

will increase the levels of fecally derived bacteria. Similarly, in Microarrays can be employed to identify bacteria, polluted aquifers and the overlying soil, unwanted bacteria may be identified. Antibiotic resistant bacteria may appear as a result of changes in their genomes and the expression of their genes. Bacterial genomes are very small and simple compared to the the use antibiotics in animals raised for food, and on crops and human genome. Nevertheless there is enormous genetic diversity orchards. Within ourselves, changes in the "normal" bacteria among bacterial genomes. The diversity is manifest in two ways. present in the intestinal tract (due, for example, to the administration of antibiotics) may decrease our resistance to First, some genes are in found in many species. These genes exhibit small changes in their sequences and as the species get subsequent infection. further apart the proportion of differences increases. Second, Proper monitoring of bacteria requires correct some species have genes that are not found in a second species classification. Traditionally, bacterial classification depends upon This is expected for organisms that manage to inhabit every niche the environmental sources of the specimen and a series of imaginable. Bacteria in different habitats will need different sets biochemical tests. These biochemical tests assay the functional of genes to survive and their small size and need for rapid growth presence of one or a few genes in the bacterial genome. In selects for discarding unnecessary genes, essence, microbiologists have exploited the limited genome size and the wide variety of enzymes necessary to survive in diverse Bacteria are found everywhere. In ourselves and other environments as a tool to classify bacteria. However, knowing the animals, bacteria are normally present in our nose and mouth, environmental source and a few of enzymes present in genome skin, and intestines. In our world, bacteria inhabit food, drinking can unambiguously classify only limited number of bacterial water, soil, aquifers, streams, rivers, beaches, oceans, sewage species. Indeed, good classification is available only for a few wastes, hot springs, volcanoes, deep sea vents, Antarctica, and medically important species. surfaces. On surfaces, biofilms containing bacteria are found anywhere there is moisture including on trees, rocks, in pipes and Microarrays have the potential to incorporate the tubing. In addition, seasonal differences have been documented, multiple biochemical tests used to classify bacteria into a single Different species of bacteria with distinct genomes have adapted test. A microarray consisting of a probe for each of the enzymes to each of these environments and conditions. In common assayed by each biochemical test could be substituted for the set environments like our intestines and freshwater, there are of biochemical tests. For example, the harmlessEscherichia coli estimated to be hundreds of species, including species which may KI2 and the potential deadly bloody diarrhea causing E. coli be unique to a particular environment. O157:H7 may be differentiated by any of the 1500 out of 5000 genes that are found in one, but not both genomes [6]. Although In certain settings, there is value to periodic monitoring of investigators were surprised by the magnitude of the number of bacterial populations, to confirm that specific bacteria are (or are genes that distinguish the two E. coli strains, the principle that not) present: among others, this includes routine monitoring of distinct strains will have a number of genetic differences was drinking water supplies, monitoring of harvest areas for shellfish, expected. Since microarrays can be created with numerous monitoring of water for recreational purposes, and monitoring of probes, the expectation is that a single microarray will be used to food and food products. This monitoring is usually performed by distinguish several environmentally and biochemically related attempting to grow the bacteria on or in appropriate bacteriologic species. However, before such a microarray can be construct the growth media. If monitoring bacteria was simple and sequence of the relevant genes and their function must be known. inexpensive, monitoring might well be performed in other Using microarrays to assign function to known DNA sequences locations as well. will be discussed later. Microarray will be employed to monitor changes in the bacterial community including changes in frequency of the An alternative microarray for classifying bacteria is to existing species and the appearance of new species. The short use sequence differences anmng homologous genes. Homology lifecycle and clear responses to selective pressure in bacteria refers to genes that are genetically related and are found in enhance the probability that fluctuation in the bacterial different organisms. The paradigm in bacteria is the 16s community will be indicators of wanted and unwanted changes in ribosomal RNA gene. Ribosomal RNA is necessary for the the environment. A well known example is that a sewage spill translation of messenger RNA into protein and found is in every known bacteria. Although some small (20-30 base pairs) regions of the 16s sequence do not vary among bacteria, the majority of