Bacterial Applications

Bacterial Culture Guide Bacterial Applications


Table of Contents

Applications

For centuries, bacterial strains have been used for the production of consumable products via fermentation. In recent years, bacteria have also been commercialized for use in quality control and the production of probiotics, antibiotics, vitamins, organic acids, and biofuel. Below, we further describe various bacterial applications. Please note that ATCC strains are for laboratory use only and are not for human or diagnostic use.

Quality Control

In the production of consumable products, it is essential that effective microbiological testing is performed to ensure the absence of contamination. The safety, reputation, and business performance of all processing companies depends on effective quality control. Strains used for quality control must have confirmed identity, viability, and purity that are backed by meticulous laboratory procedures that minimize subculturing. Since 1925, ATCC has been a leading provider of QC bacterial strains and has set the standard for authenticating and distributing biological materials for research and product testing. All bacterial strains authenticated and provided by ATCC have gone through both rigorous phenotypic and genotypic characterization; these procedures are described in detail in the previous chapter, “Bacterial Authentication

Consumable Products

Bacterial strains are commonly used in the production of various fermented food products including vinegar, pickled goods, or an assortment of dairy products. These consumable products are generated by the fermentation of compounds such as lactose or ethanol into lactic- or acetic-acid, respectively. For example, in the production of cheese and yogurt, Lactobacillus, Streptococcus, and Bifidobacterium species are commonly used for lactose fermentation. The subsequent formation of lactic acid results in a change in both the texture and flavor of the milk product. In contrast, vinegar generation requires the fermentation of ethanol by Acetobacter species, resulting in an aromatic, tangy product. Overall, as compared to many non-fermented foodstuffs, these aforementioned products are often less susceptible to spoilage and may provide additional health benefits such as improved digestion.

Probiotics

Probiotic bacterial species are thought to be beneficial to the host organism. When administered in adequate amounts, these live strains can promote healthy digestion, absorption, and a reduction in the number of enteric pathogens.37 Lactobacillus and Bifidobacterium species are the most commonly used probiotic bacterial strains and are often provided within fermented foods such as yogurt. Species within these genera have been found to naturally synthesize antibiotics, vitamins, and amino acids. Additionally, these microbes promote favorable pH levels and the absorption of nutrients including calcium, magnesium, and iron. Overall, the antimicrobial properties and health benefits associated with probiotic strains can promote proper bowel function and assist in the treatment of various conditions including gastroenteritis, colitis, and irritable bowel syndrome.

Vitamins

Many bacterial strains produce several B- and K-complex vitamins to aid in a variety of metabolic processes including DNA synthesis and the catabolism of fats, carbohydrates, or proteins. Human intestinal bacteria, for example, are known to synthesize vitamin K1, biotin (B7), folic acid (B9), niacinamide (B3), cobalamin (B12), riboflavin (B2), pantothenic acid (B5), and thiamine (B1). Many of these bacterial-produced vitamins are used in humans as coenzymes or cofactors and are considerably essential for proper metabolism. In particular, vitamin K is necessary for the formation of several blood-clotting factors in the liver. In contrast, both pantothenic acid and biotin function as coenzymes in carbohydrate oxidation and carboxylation reactions, respectively.

Antibiotics

Antibiotics are compounds used to either destroy or impede the growth of bacterial or fungal microorganisms via a variety of mechanisms such as the inhibition of protein or DNA synthesis. Many currently known antibiotics are produced by members of the bacterial class Actinomycetes; in particular, by members of the genus Streptomyces. Streptomyces species are filamentous soil bacteria that produce antibiotics through secondary metabolite pathways using various precursors such as amino acids, small fatty acids, sugars, and nucleic acids.38 Bacterial strains are believed to produce antibiotics as a means to diminish or eradicate the growth of other invading species that may be either harmful or in competition for a similar food source. Within human society, antibiotic production is critical for the treatment of infectious diseases and is often used agriculturally in the biological control of plant pathogenic microorganisms.39

Organic Acids

Various organic acids, such as citric, lactic, succinic, and gluconic acid, can be produced by bacterial species as a metabolic byproduct. Citric acid, for example, is a byproduct of the Citric Acid Cycle and is therefore important in metabolism. In contrast, the production of lactic acid often occurs as an end product to lactose fermentation. Organic acids are applicable for a variety of purposes including food preservation, emulsification, and flavoring. They have also been used in a more industrial function within buffer solutions, detergents, cosmetics, and rust removers.

Biofuels

Currently most of our energy is supplied through petroleum, coal, and natural gas deposits. These sources of energy, however, are both finite and non-renewable. Recently, efforts have been made to generate sustainable energy via the production of biofuels from commercially available products such as corn and sugar cane. However, these novel sources of energy require food to be used as fuel rather than for human sustenance. To resolve these aforementioned issues, current biofuel research is focusing on the use of bacteria in the catabolism of cellulose into desired hydrocarbon fuel compounds. The goal is to engineer bacterial strains that have metabolic pathways that can generate biofuels through the degradation of biowastes or weeds, thus creating a sustainable form of energy without diminishing the food supply

Reporter-labeled Strains

Fluorescence- and luminescence-based reporter-labeled strains have a diverse array of applications in the basic and applied sciences, including microbial quantification and detection, the analysis of hostpathogen interactions, drug discovery, and food testing. For example, these strains provide a unique tool for analyzing the invasion, colonization, localization, and pathogen load of a specific bacterial pathogen within host cells and tissues under different physiological conditions or stages in an infection cycle. Further, this ability to easily visualize and quantify bacteria allows for an efficient means of screening a large number of antimicrobial therapeutics and determining the growth inhibitory dose. Overall, these studies could significantly contribute to the knowledge of microbial pathogenesis, with significant implications in the development and evaluation of novel therapeutics and quality control assays.