Microbiology

A.Y. 2020/2021
6
Max ECTS
56
Overall hours
SSD
AGR/16
Language
Italian
Learning objectives
To provide basic knowledge on microbial world, mandatory to
properly study following microbiology-related courses. Specific
attention will be given to agro-food bacteria and microorganisms
involved in carbon and nitrogen cycles in soil.
Expected learning outcomes
Knowledge of morphology and biochemical structure of bacteria
and viruses; methodologies of isolation and identification (by
classic and molecular methods) of specific bacteria; knowledge of
microbial energetic metabolism; comprehension of the principles
supporting ecological adaptation, selection and genetic variability
of bacteria.
Course syllabus and organization

Single session

Lesson period
First semester
To provide the teaching offer to all students in compliance with the restrictions established by regulations relating to COVID 19 emergency, the lessons will be held synchronously through the Microsoft Teams platform in accordance with the official calendar. The audio and video recordings of the lessons will be available to students asynchronously through the Ariel platform and/or Microsoft Teams.

In addition, the course will include 6 hours of classroom meetings for the two on-going (in itinere) tests, intended exclusively for those students who have participated in the sync lessons. Students can choose to participate by registering through the booking application made available by UNIMI.

Verification: written exam in classroom at the Faculty. If the presence at the Faculty won't be possible, the exam will be oral through the Microsoft Teams platform. Registration to the exam session through UNIMIA system is mandatory.

The procedures of carrying out the laboratory exercises will be communicated during the first lessons of the course.
Course syllabus
Introduction to microbiology; the classification of living organisms; the optical microscope. Gram staining. The bacterial cell wall. The cell wall of Saccharomyces cerevisiae. The capsule; flagella, cilia and pili; the 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 requirements of microorganisms: microorganisms and oxygen. The chemical / physical environmental needs of microorganisms: microorganisms and osmotic pressure (water activity). Bacterial reproduction: the bacterial growth curve; asexual reproduction of Saccharomyces cerevisiae. Culture 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 inoculum. The determination of the microbial count with direct and indirect measurements: the total microbial count with counting chambers; description and examples of calculation for the viable count by serial decimal dilutions (the concept of CFU, the weighted average for the calculation of the CFU). Eumycetes: filamentous fungi, the classification of eumycetes based on asexual and sexual reproduction. Soil bacteria. Interaction soil-plant-microorganisms: the rhizosphere, the root nodules of legumes, nitrogen fixation, Agrobacterium, mycorrhizae. Introduction to cellular metabolism: ATP and its formation. Free electron transporters (NAD and NADP). The pyruvate production pathways: Embden-Meyerhof, pentose phosphate and Entner-Doudoroff pathways. The definition of the catabolic processes of respiration and fermentation. The different types of fermentation in bacteria (the alcoholic, lactic, mixed acid, butilenglicole, propionic, butyric and omoacetic fermentations). The fructose-6-phosphate phosphoketolase pathway. Lactic acid bacteria and their metabolism; acetic bacteria and their metabolism. Outline of anabolism. Principles of microbial genetics; the central dogma of biology; transcription regulation (the lac operon, the operon, tryptophan operon, maltose regulon); 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 evaluation of student preparation. 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.

Program of the laboratory exercitations
During the practical part of the course in the didactic laboratories, the importance and the modalities through which working in sterility in microbiology (explanation of the bunsen burner, oxidizing flame, cone of sterility) are illustrated; the instruments used in classical microbiology are shown and used (loops, spatulas, pipettes, test tubes, slants, shaking flasks, Petri dishes, liquid and agar culture media); it is taught how to prepare serial decimal dilutions starting from a sample of unknown concentration and then continuing with spread plate and encapsulation techniques on selective culture media, following which it is explained how to perform the viable count calculation from the colony forming units grown on the plate; from suspensions of yeasts or bacteria of unknown concentration, it is shown how to perform a calculation of total counts through the counting chamber with an optical microscope; the technique of plate striping is shown to obtain isolated colonies and pure cultures with the use of selective media; examples of biochemical assays to be performed on agar plates are shown to highlight some microbial enzyme activities (catalase, amylase, protease); tests of fermentative metabolism of lactobacilli are carried out with tests of use of different sources of sugars, and how the growth of anaerobic microorganisms is promoted; the 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 bacteria stained from complex food matrices.
Prerequisites for admission
Principles of biology and basic concepts of organic chemistry
Teaching methods
The teaching will be delivered through lectures lasting 2 academic hours. Furthermore, practical exercitations are planned at the educational microbiology laboratory; the communication of the dates of the exercitations and the registration to them takes place during the first lessons in the classroom.
Teaching Resources
Exam preparation material is available in Ariel and in Microsoft Teams. The reference texts and other information are available in the file called "Organizzazione del corso e modalità d'esame" available in Ariel and in Teams.
Assessment methods and Criteria
- Type of exam: a written test with open answers lasting 60 minutes. Students can take part in the test only after registering through the UNIMIA services (formerly SIFA). Furthermore, there are two ongoing (in itinere) tests for students attending the lessons.
- Evaluation parameters: demonstration of acquisition of the concepts; ability to organize knowledge discursively. Importance will be given to the correct use of the specialized vocabulary.
- Evaluation: mark out of thirty.
- Method of communicating the results of the test: through the UNIMIA services (formerly SIFA) with the possibility of refusal of the vote by the student.

N.B.: during COVID-19 emergency, exams will consist of oral test through Microsoft Teams.
AGR/16 - AGRICULTURAL MICROBIOLOGY - University credits: 6
Laboratories: 16 hours
Lessons: 40 hours
Educational website(s)