69153 - Biology Of Microrganisms

Learning outcomes

After this course, the student knows the structural, physiological and metabolic characteristics of the various microbial species and is able to manage and optimize the activity in the fermentative processes for the transformation of food raw material and to prevent the activity of pathogenic and toxinogenic microorganisms

Course contents

Introduction. What is microbiology and general descriptions. Difinition of microrganisms and importance of the microbiological heritage.

Bacterial classification. Phylogenesis. Methods for classification; genotype and phenotype. Definition of the most important genera and species of interest for the Food sector. Taxonomy of Bacteria: most important Phyla (Proteobacteria, Firmicutes, Actinobacteria). Characteristics of the main microbial groups: Pseudomonadacee, Enterobacteriacee, Acetobacteraceae, Acinetobacter and Chromobacterium, Vibrio e Photobacterium, lactic acid bacteria, Bacillus, Clostridium, Staphyilococci, Micrococci, Listeria, Corinebacteria, propionic bacteria, bifidobacteria.

Taxonomy of fungi: yeasts and moulds. Sexual and asexual reproduction among fungi: ascomycetes and basidiomycetes.

Structure of cells. Composition and functions of the microbial cells. Eukaryotic and prokaryotic cells: differences and common traits. Morphology and structure of microbial cells. Spore formation.

Microbial growth. Culture media: definition, classification, preparation. Microbial counting. Microbial growth curve: lag, exponential, stationary ans death phase. Diauxic growth. Chemostats. Homeostasis. Main factors able to influence growth curve: temperature, pH, aw and oxygen.

Nutrition and transport systems. Chemical component of cells. Energy (phototrophy, chemiotrophy, lithotrophy). Organic substance (autotrophy and organotrophy). Growth factors. Transport systems (primary, secundary group translocation).

Microbial metabolism. Energetic strategies. Fermentation and respiration. Electronic chain, redox potential and bioenergetics. Membrane carrier (NADH, quinones, cytochrome, Fe S proteins, flavoproteins). Proton Motive Force (PFM). ATP and CoA. Steps of the generation of PFM. ATPase

Energetic pathways. Glicolysis, Entner Doudoroff pathway. Oxidation of pentose phosphate. Fermentations: homolactic, heterolactic, alcoholic, mixed acid, butandiolic, acetic, butyric, propionic, homoacetic, bifidobacteria pathway, Stickland reaction. Aerobic and anaerobic respiration. Krebs cycle. Anapleorotic and glyossilic pathway. Catabolism of macromolecules.

Assimilative metabolism and biosynthesis. Key intermediate products. Gluconeogenesis. Nitrogen assimilation. Sulphur assimilation. Phosphate assimilation. Aminoacid biosynthesis, Nucleotide biosynthesis.

Virus: Viral structure. Genetic material in viruses. Steps of viral replication. Bacterial viruses (fagi). Virulent fagi virulenti and temperate fagi. Characteristic of lysogenic fagi

Laboratory classes will be held by Prof. Andrea Gianotti (2 CFU)

Laboratory work will provide students an opportunity to apply theoretical and conceptual knowledge and will include:

• use of an optical microscope to observe different cell morphologies: bacteria, yeasts and moulds
• techniques for the purification and characterization of microbial isolates
• staining to differentiate and highlight components of the microbial cells: Gram and spore staining
• physiological and enzymatic test for the characterization of microbial isolates: catalase, oxidase, Voges-Proskauer test.
• tests to evaluate nutrients, oxygen and growth temperature requirements
• identification of isolates
• enumeration of cell cultures through direct and direct methods: optical density, Thoma cell counting chamber, direct plate counting
• evaluation of cell growth by plate counting techniques (inclusion and surface inoculum)
• analysis and discussion of experimental data: construction of growth curves and determination of growth parameters

 

Readings/Bibliography

Brock. Biologia dei microrganismi. Microbiologia generale, ambientale e industriale. Pearson editor

Teaching methods

Theorical lessions and pratical laboratory course. If possible, seminars and lectures with experts in the field will be organized. Also guided tour in food industry, when possible, will be planned.

Assessment methods

The preparation of the students will be tested through a test with two types of questions. There are three open questions for each of which a maximum score of 3 points will be assigned. Then there are 25 multiple choice questions, for each of which a maximum of 1 points will be assigned. The time available to complete the test is 90 minutes. Text books, notes, and other tools are not admitted. The test is passed if a score of 18 points is reached. Score of 33 determines the obtaining of laude.

The final evaluation of the the course "Biology of Microorganisms and Food Inspection" is calculated as the arithmetic meas of the two units "Biology of Microorganisms" and "Food Inspection". Because it is an integrated course, the final score will be registered by Prof. Gerardo Manfreda

Teaching tools

Slides and seminars

Office hours

See the website of Francesca Patrignani

See the website of Andrea Gianotti