Microbiology

Overview of Microbiology

  • Microbiology is the scientific study of microorganisms, including bacteria, viruses, archaea, fungi and protozoa.
  • These microscopic organisms are ubiquitous in nature and play crucial roles in ecosystems, including the energy flow and nutrient cycling.

Types of Microorganisms

  • Bacteria are prokaryotic microorganisms, typically single-celled, that come in various shapes and sizes. They are crucial for processes like nitrogen fixation and decomposition.
  • Archaea, also prokaryotic, physically resemble bacteria but metabolically and genetically are distinct. They inhabit extreme environments such as hot springs and salt lakes.
  • Protozoa are single-celled eukaryotes that display heterotrophic mode of nutrition, often consuming bacteria, archaea and other protozoa.
  • Fungi are eukaryotic organisms that can be single-celled (yeasts) or multicellular (mushrooms, moulds). They act as decomposers and are integral to nutrient cycles.
  • Viruses are unique as they are not cells, but nucleic acid-protein complexes that infect host cells to replicate.

Cellular Respiration in Microorganisms

  • Microorganisms like bacteria and fungi undertake cellular respiration, a set of metabolic reactions transforming nutrients into ATP, the energy currency in cells.
  • This involves glycolysis, the Kreb’s cycle and the electron transport chain, occurring in the cytosol and across the cell membranes in prokaryotes.
  • Oxygen serves as the final electron acceptor in aerobic respiration, while other molecules like sulfate or nitrate can act as electron acceptors in anaerobic respiration.

Fermentation in Microorganisms

  • When oxygen is unavailable, some microorganisms execute fermentation, an anaerobic process that allows them to continually perform glycolysis to generate ATP.
  • In alcoholic fermentation, glucose is converted into ethanol and carbon dioxide. This is performed by yeasts and some bacteria, with large industrial applications.
  • In lactate fermentation, glucose is converted into lactic acid. This is carried out by certain bacteria (e.g., Lactobacillus) and is crucial in dairy production.

Photosynthesis in Microorganisms

  • Photosynthetic bacteria, like cyanobacteria, and green algae convert sunlight into chemical energy similarly to plants. They utilize chlorophyll or bacteriochlorophylls for this.
  • The process involves light-dependent reactions and a light-independent reaction (Calvin cycle), creating glucose and releasing oxygen.

Impact of Environmental Factors on Microbial Activity

  • Environmental factors such as temperature, pH, and nutrient availability impact the rate of microbial processes, including photosynthesis and respiration.
  • Optimal conditions are necessary for these processes with any deviations causing decreased activity or possibly leading to cell death.

Importance of Microbiology in Energy Cycling and Biotechnology

  • Microbiology is crucial in understanding energy cycling in ecosystems and harnessing such processes for biotechnological applications.
  • This includes waste treatment, biofuel production, and the creation of fermented foods.