Overview of Environmental Microbiology

Overview of Environmental Microbiology

• Environmental microbiology is the study of microbial communities in the environment (soil, water, air, and sediments) and their application in resolving environmental problems.
• The field interfaces with various subspecialties, including soil, aquatic, and aeromicrobiology, bioremediation, water quality, occupational health and infection control, food safety, and industrial microbiology.

Mission of Environmental Microbiologists

• The mission is to pursue environmental sustainability, which is the utilization of environmental resources for human health and welfare without harming the physical environment or biological communities.

Characteristics of Microbes

• Microbes are small (10-6 m = 1 μm), unicellular, and diverse in metabolism and physiology.
• They can produce energy in different ways (heterotrophic and autotrophic) and are adaptable, ubiquitous, and can survive in various environments.

Prokaryotes

• Prokaryotes include bacteria and archaea, which are small (0.1-600 μm), unicellular, and have diverse metabolism and physiology.
• They are ubiquitous, with 10^6 cells/mL in natural waters and 10^9 cells/g in soils and sediments.

Cell Morphology

• Bacterial shapes include coccus, rod, spirillum, spirochete, stalk, hypha, and filamentous.
• Cell size varies with nutritional state, and smaller cells have a higher surface-to-volume ratio, allowing them to take up nutrients efficiently.

Chemical Composition

• Bacteria and archaea have a dry weight (DW) to wet weight (WW) ratio of 0.2-0.4, with 70% water content.
• The DW composition includes C (50%), P (3%), O (20%), K (2%), N (14%), S (1%), and others.

Bacterial Cell Walls

• Bacteria are classified into Gram-negative and Gram-positive based on their cell walls.
• Peptidoglycan is the primary component of bacterial cell walls, and Gram-positive bacteria have a higher peptidoglycan content.

Appendages

• Flagella (singular flagellum) allow bacteria to move towards a point source of nutrients.
• Fimbriae (singular fimbria) aid in attachment to surfaces and are involved in biofilm formation and infection processes.
• Pili (singular pilus) are involved in mating processes and are found only in Gram-negative bacteria.

Internal Structure

• Ribosomes turn mRNA into proteins and are evolutionarily conserved structures.
• Cytoplasm is the gel-like fluid that fills each cell, providing an aqueous environment for chemical reactions.
• DNA contains the genetic material and instructions for the cell's abilities and characteristics.

Eukaryotes

• Eukaryotes include protozoa, fungi, and other organisms that are found in freshwater, marine, and soil environments.
• They can be free-living, parasitic, or mutualistic and have ecological importance in nutrient recycling, wastewater treatment, and as environmental quality indicators.

Ecological Importance of Protozoa and Fungi

• Protozoa aid in nutrient recycling, sustain bacterial populations, and participate in wastewater treatment.
• Fungi can degrade complex polymers, produce useful byproducts, and have pharmaceutical importance.