Fundamentals of Biochemical Engineering Part 1 - Bailey J., Ollis D. 1989

Introduction to Microbiology
Major Cell Types

This section briefly reviews the Classification of the Kingdom Protista, which encompasses All living organisms with a very simple biological Organization compared to plants and animals. The protist kingdom includes all unicellular organisms, as well as multicellular forms composed of Cells of a single type only. In contrast, plants and animals feature a wide diversity of Cell types. At the end of this section, we will provide Examples of PLANT AND ANIMAL cells that can be cultivated on solid or liquid nutrient media.

Table 1.1 illustrates the division of the protist kingdom into taxa suitable for our purposes. These taxa differ in A number of characteristics: their sources and Methods of obtaining energy and nutrients, growth and excretion rates, modes of reproduction, motility and the means by which it is achieved. All these factors are crucial for the practical utilization of protists. Morphological differences—that is, variations in shape and Structure—also play a significant role in classifying various types of organisms. A microorganism's Morphology affects the mass transfer rate of nutrients and can also substantially determine the dynamic properties of Suspensions containing that Organism. All the data cited above indicate that each of the microbial taxa listed in Table 1.1 should be considered separately.

Class="center">Table 1.1. Classification of organisms in The Kingdom Protista

The art of biological classification is known as Taxonomy. Within this classification, the basic unit is the species; organisms of the same species are characterized by a high degree of morphological and biochemical similarity, while differing significantly in these properties from organisms of closely related species. A biological species is designated by two Latin words, the first of which is capitalized and denotes the genus of the organism, while the second (often descriptive) denotes the species itself. For example, the colon bacillus—a thoroughly studied bacterium found in the human intestine—is called Escherichia (genus name) coli (species name). Latin names are italicized; if the genus is clear from the context, the genus name is usually abbreviated to its initial letter, e.g., E. coli.

To organize species and genera systematically, a hierarchical taxonomic system has been developed, in which related genera are grouped into families, closely related families form orders, which in turn combine into classes; classes are then grouped into divisions, or phyla, and finally, related divisions are united into kingdoms. For example, Table 1.1 indicates the kingdom Protista, the division of Fungi, and the class of Yeasts. Often, however, differences in microbial properties are not clearly defined, making detailed classification somewhat artificial and arbitrary, particularly in the case of Bacteria and yeasts.