#Bacillus subtilis endospore stain manual#

Many of the Gram negative bacteria residing in the GI tract are members of the Family Enterobacteriaceae. Generally, Gram positive cocci and bacilli are considered “probiotic” because of the health promoting benefits associated with these bacteria, while Gram negative species are commensals that can induce inflammation if their proliferation is not kept in check. The small and large intestines are home to the largest number of bacterial species, which contribute greatly to human health and disease. In a clinical laboratory, differentiating the nonpathogenic microbiota found in the GI tract from pathogenic species has historically relied on phenotypic tests. Oxygen Growth Requirement Category_ Differentiating Among Bacterial Species State what evidence from test results indicates the bacteria use this pathway. _ Colonial morphologyĭistinguishing among bacterial species begins with examining colonial morphology, which you will do using the cultures listed below: Write the name and BSL for each of the cultures below: Observable differences start at the cellular level.Ī volunteer from your lab bench should obtain cultures from your instructor, who will provide you with the species names. The bacteria we will examine in this lab include both Gram positive and Gram negative species of bacilli, each in a different genus. Morphological Evaluation of Bacterial Isolates And like last week, we will begin by observing colonial and cellular morphology. Once again, although they are morphologically similar, the bacteria who have “volunteered” for this week’s lab differ in many ways and can be distinguished from each other by observing morphological and physiological characteristics. Using previous methods and additional tests, we will develop profiles of the bacilli as a way to distinguish among the various species.

The group of bacteria included in this lab includes both Gram positive and Gram negative species.

Gram-negative bacilli are typically distinguished by size, shape, motility, and oxygen growth categories. Gram positive bacilli are further subdivided according to whether they form endospores, have filamentous growth or hyphae, and if they are acid-fast.

#Bacillus subtilis endospore stain manual#

A few species of bacilli produce endospores or other types of cellular inclusion bodies, such as metachromatic granules and parasporal crystals.īergey ’ s Manual initially divides the bacilli according to Gram stain reaction. Some bacilli are short and plump little rods, while others are extremely slender and long.

To continue the investigation, we will use a similar approach to examine the cellular and metabolic characteristics of a second group of bacteria, this time all bacilli.īacilli show great diversity at the cellular level, beginning with the overall size and shape of the cells themselves. Previously, we studied the colonial, cellular, and chemical characteristics of a group of bacteria that had a common cellular morphology (they were cocci), but were quite diverse metabolically.