Diagnostic Microbiology for the Laboratory Sciences - Essay Example

The major groups of glucose-fermenting bacteria include Escherichia coli, Streptococci (e.g. Streptococci lactic), and Lactobacilli (e.g. Lactobacillus casei, L. pentoses), which produce lactic acid as the end product of fermentation (Buchanan & Cibbons, 1974). Other glucose-fermenting bacteria that produce these acids are Proteus, Shigella, Salmonella, Escherichia coli, Microbacterium, and Leuconostoc (Buchanan & Cibbons, 1974).

Organisms producing measurable acid by-products

When using the phenol red indicator in the broth media, two bacterias that ferment glucose were E. coli and Shigella sonnei, they produced measurable acid by-products because the broth media changed from red to yellow. Therefore, organisms like Escherichia coli ferment glucose through fermentation thereby liberating large amounts of three types of acids succinic, lactic, and acetic, which change the media from yellow to red (McDevitt, 2009).

Uses of Voges-Proskauer test

The Voges – Proskauer test is appropriate because of the detection capability of acetoin, which is produced by the bacteria that use it as a metabolic intermediate by following the butane diol pathway (Buchanan & Cibbons, 1974). This test is used when differentiating Escherichia coli from other Enterobacter species like Enterobacter aerogenes because E. coli is positive in Methyl red yet negative Voges-Proskauer while the Enterobacter aerogenes is negative in Methyl red test and positive in Voges-Proskauer (McDevitt, 2009).

Organisms using alternative pathways to metabolize glucose

Availability of the main source of food determines the enzymes and the pathway of glucose metabolism because different nutrients require specific enzymes hence determining the pathway (Dannessa, 2014). However, alternative pathways are used when organisms require a specific amount of ATP since different pathways produce a certain amount of ATP after the oxidation of glucose (Dannessa, 2014).