Food Science: General and Food Microbiology

General and Food Microbiology Course Overview

• The course includes 30 hours of lectures and 30 hours of laboratory classes
• Laboratory classes will be held at the Department of Food Biotechnology and Microbiology
• Students are required to obtain specific materials, including a white cotton lab coat, a student's notebook, and other laboratory equipment

Microbiology Definition and History

• Microbiology is the study of microorganisms, defined by the size of the organisms studied and the techniques employed
• The study of microorganisms spans from ancient times to the present day, with contributions from scientists such as Roger Bacon, Antonie van Leeuwenhoek, and Louis Pasteur
• The spontaneous generation theory was disproved by scientists such as Francesco Redi, John Needham, and Lazzaro Spallanzani, leading to the development of modern microbiology

Microbiology Branches

• General microbiology branches include:
  • Bacteriology: the study of bacteria
  • Mycology: the study of fungi
  • Phycology: the study of algae
  • Virology: the study of viruses
  • Parasitology: the study of parasites
• Applied microbiology branches include:
  • Agricultural microbiology
  • Medical microbiology
  • Microbial biotechnology
  • Industrial microbiology
  • Pharmaceutical microbiology
  • Veterinary microbiology
  • Environmental microbiology
  • Soil microbiology
  • Water microbiology
  • Food microbiology

Microscopy

• Light microscopy uses a system of optical lenses to produce an image
• Electron microscopy uses a beam of electrons to produce an image
• Types of light microscopy include:
  • Bright-field microscopy
  • Dark-field microscopy
  • Phase contrast microscopy
  • Differential interference contrast microscopy
  • Fluorescence microscopy
• Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are two types of electron microscopy

Microbial Structure and Classification

• Microorganisms can be classified based on their size, shape, and structure
• The classification of microorganisms includes taxonomy, nomenclature, and identification
• Taxonomic ranks include domain, division, class, order, family, genus, and species
• Phylogenetic trees are used to represent the evolutionary relationships between microorganisms

Tree of Life

• The tree of life represents the evolutionary relationships between all living organisms
• The tree of life is divided into three domains: Archaea, Bacteria, and Eukarya
• Key events in the history of life on Earth include the formation of the Earth, the emergence of life, and the development of multicellular life

Taxonomy and Phylogeny

• Taxonomy is the classification of microorganisms based on their mutual similarity or evolutionary relatedness
• Phylogeny is the study of the evolutionary relationships between microorganisms
• Taxonomic ranks include domain, division, class, order, family, genus, and species
• Phylogenetic trees are used to represent the evolutionary relationships between microorganisms### Cellular Characteristics
• Bacteria and Archaea lack a membrane-enclosed nucleus with a nucleolus, whereas Eucarya have one.
• Complex internal membranous organelles are absent in Bacteria and Archaea, but present in Eucarya.
• Cell walls in Bacteria typically contain peptidoglycan with muramic acid, whereas Archaea have varied types without muramic acid, and Eucarya lack cell walls with muramic acid.

Membrane Lipid Structure

• Bacteria have ester-linked, straight-chained fatty acids in their membrane lipids.
• Archaea have ether-linked, branched aliphatic chains in their membrane lipids.
• Eucarya have ester-linked, straight-chained fatty acids in their membrane lipids.

Other Characteristics

• Gas vesicles are present in Bacteria and Archaea, but absent in Eucarya.
• Metabolism and similar ATPase are present in all three domains.
• Methanogenesis is absent in Bacteria, present in Archaea, and absent in Eucarya.
• Nitrogen fixation is present in Bacteria and Archaea, but absent in Eucarya.
• Chlorophyll-based photosynthesis is present in Bacteria, absent in Archaea, and present in Eucarya.
• Chemolithotrophy is present in Bacteria and Archaea, but absent in Eucarya.

RNA Characteristics

• Polycistronic mRNA is present in Bacteria and Archaea, but absent in Eucarya.
• mRNA introns are absent in Bacteria and Archaea, but present in Eucarya.
• mRNA splicing, capping, and poly(A)tailing are absent in Bacteria and Archaea, but present in Eucarya.

Ribosome Characteristics

• Bacteria and Archaea have 70S ribosomes, while Eucarya have 80S cytoplasmic ribosomes.

RNA Polymerase Characteristics

• Bacteria have one DNA-dependent RNA polymerase with a simple subunit pattern.
• Archaea have several DNA-dependent RNA polymerases with complex subunit patterns similar to eukaryotic enzymes.
• Eucarya have three DNA-dependent RNA polymerases with complex subunit patterns.