Bacteria are divided into two kinds, depending on their ability to absorb carbon dioxide from the environment. Heterotrophic bacteria-HB obtains carbon dioxide from organic substances like carbohydrates and proteins. Most bacteria are heterotrophic, including human pathogens and the majority of bacteria found in drinking water systems. Numerous varieties of heterotrophic bacteria are found in nature. Heterotrophic Bacteria play a vital part in the natural recycling of substances.
Habitat of Heterotrophic Bacteria
Heterotrophic bacteria are abundant in the environment, especially water -- including treated water and tap water. Due to its capacity to adapt itself to a malnourished environment of water systems, heterotrophic bacteria are able to outlive other microorganisms in water. The bacteria can exist in both high oxygen and low oxygen surroundings. They use organic substances from their natural habitat to generate energy, for general metabolism and for material to synthesize their own compounds.
Role of Heterotrophic Bacteria
Heterotrophic bacteria are an integral part of the ecosystem, as their significance in the denitrifying and decay process cannot be denied. Through respiration and fermentation, these bacteria release back many inorganic compounds into nature, which can be utilized by other living beings. These bacteria emit exoenzymes that can break down cellulose, lignin, keratin and other natural molecules that are difficult to decompose. The denitrifying and decomposition processes would not be able to take place as effectively without the functions carried out by these microorganisms.
Heterotrophic Plate Count-HPC
Heterotrophic Plate Count is a term that refers to the development of viable bacteria that exists naturally in water. HPC not only assesses the quality of disinfected water, but it also provides guidelines regarding the maintenance of disinfection residuals, the detection of the absence of bacterial regeneration and the efficacy of water treatment generally. In HPC, heterotrophic bacteria are isolated in non-selective, low nutrient, solid gel matrix called R2A agar. This water sample is left to incubate for five to seven days at room temperature by creating similar conditions that are conducive to the survival of these organisms. Results are measured by the growth of concentric bacterial colonies on the isolated sample plate.
Health Implications of Heterotrophic Bacteria
Since water contains a profuse amount of heterotrophic bacteria, health organizations all over the world have laid guidelines regarding a safe level of heterotrophic bacteria that water used for human consumption may contain. Heterotrophic bacteria may be present in drinking water even after it has been treated chemically. Sometimes these microbes may be pathogenic in nature, but in most cases do not have any adverse effects on human beings. According to a 2003 World Health Organization Conference entitled “"HPC and Drinking Water Safety: The Significance of Heterotrophic Plate Counts for Water Quality and Human Health,” it was concluded that heterotrophic bacteria does not hold any significant health concerns to consumers of drinking water.