Microbiology

Introduction to microbiology; the classification of living beings; the optical microscope. The Gram stain. The bacterial wall. The cell wall of Saccharomyces cerevisiae. The capsule; flagella, cilia and pili; bacterial endospore. Examples of spore-forming bacteria: Bacillus thuringiensis, Bacillus licheniformis and Clostridium botulinum. The cell membrane and membrane transport. The nutritional and energy needs of microorganisms. The chemical / physical environmental needs of microorganisms: microorganisms and oxygen. The chemical / physical environmental needs of microorganisms: microorganisms and osmotic pressure (water activity). Bacterial reproduction: the bacterial growth curve; the asexual reproduction of Saccharomyces cerevisiae. Cultivation media: classification based on physical state, chemical composition and function. The concept of sterility and the tools used for work in sterility; the types of sowing. The determination of the microbial load with direct and indirect measurements: the total microbial count with counting chambers; description and calculation examples for the vital count with the method of sowing serial decimal dilutions (the concept of CFU, the weighted average for the calculation of CFU). The eumycetes: filamentous fungi, the classification of eumycetes on the basis of asexual and sexual reproduction. Soil bacteria. Soil-plant-microorganism interactions: rhizosphere, root nodules of legumes, nitrogen fixation, Agrobacterium, mycorrhizae. Introduction to cellular metabolism: ATP and its formation. Free electron carriers (NAD and NADP). The production routes of pyruvate: Embden-Meyerhof route, pentose phosphate and Entner-Doudoroff. The definition of the catabolic processes of respiration and fermentation. The different types of fermentation in bacteria (alcoholic, lactic, mixed acid, butylene glycol, propionic, butyric and homoacetic fermentations). The fructose-6-phosphate phosphoketolase pathway. Lactic bacteria and their metabolism; acetic bacteria and their metabolism. Hints of anabolism. Principles of microbial genetics; the central dogma of biology; the regulation of transcription (lac operon, operon, tryptophan operon, regulon maltose); protein synthesis in prokaryotes. The concept of life in biology and viruses; bacteriophages; the plasmids. How microbial biodiversity is generated: horizontal gene transfer. The mechanisms of natural genetic recombination in bacteria: transformation, conjugation and transduction. Ongoing assessment of students' preparation. The polymerase chain reaction. Taxonomy and bacterial identification. The 16S rRNA gene; the 16S rRNA gene in bacterial identification and in the study of bacterial phylogeny.

Laboratory activities program
During the exercises in the educational laboratories, the importance and ways of working in sterility in microbiology are illustrated (explanation of the Bunsen burner, oxidizing flame, sterility cone); the instruments used in classical microbiology are shown and used (loops, spatulas, pipettes, test tubes, slants, flasks, Petri dishes, liquid and agarized culture media); taught how to prepare decimal serial dilutions starting from samples of different origin of unknown concentration and then continue with sowing techniques by spatulation and incorporation on selective soils, following which it is explained how to perform the calculation of vital count from the colony forming units grown in the plate ; from suspensions of yeasts or bacteria of unknown concentration it is shown how to perform a calculation of the total count through the counting chamber under the optical microscope and also the viable count by means of methylene blue; the smear seeding technique is shown to obtain isolated colonies and pure cultures with the use of selective media; examples of biochemical assays to be carried out in plates are shown to highlight some microbial enzymatic activities (catalase, amylase, protease); tests of fermentative metabolism of lactobacilli are carried out with assays of use of different sources of sugars, and how the growth of anaerobic microorganisms is promoted; Gram staining is explained and performed; the principles of phase contrast optical microscopy are illustrated, with examples of observation of fresh preparations of different bacteria and yeasts, and of staining of bacteria from complex food matrices.