Bioaugmentation is the addition of bacterial cultures required to speed up the degradation of a contaminant.
One of the most common applications of bioaugmentation is to remove soil contaminants or pollutants due to industrial waste/ by-products. Polycyclic and halogenated aromatic hydrocarbons make up a large percentage of the contaminants originating from oil refineries, wood preservatives, and pharmaceutical industries. These chemicals are very dangerous due to their high mutagenic and carcinogenic properties, as well as their ability to accumulate up the food chain.
Different chemical approaches to clean up of pollutants are the most effective but they are also the most costly. Bioremediation is used because certain microbes posses the ability to efficiently break down toxic pollutants.
Some issues with bioaugmentation are the survival of certain strains which is influenced by biotic and abiotic factors. Some abiotic factors include temperatures, Ph, moisture and nutrient content. Biotic factors include competition between indigenous and exogenous microorganisms.
Delivery of microorganisms to an area can be quite challenging if the contaminant is underground. Different methods of distribution have been used to penetrate the surface such as applying microorganisms with foams or surfactants.
Microorganisms for bioaugmentation- A majority of microorganisms used for bioaugmentation were isolated from contaminated areas and industrial wastewater treatment plants. The gram negative microbe, Pseudomonas, is commonly used because it has been well studied. But in many cases mixtures of microorganisms suitable for contamination clean up were more effective than a single strain.
Genetically Modified Organisms- In order to enhance the biodegradation of certain bacteria, different genetic techniques have been used. Conjugation, a type of horizontal gene transfer, is one method to transfer different catabolic encoded plasmids to endogenous microbial species. This is a useful technique since most bacteria are capable of up-taking foreign DNA and transcribing it to a functional protein. Another reason this is advantageous is because you are not introducing another specie into an area. Bioaugmentation is not a brand new field but the use of next generation sequencers and other genetic techniques has allowed scientists to isolate and analyze complex cultures, in order to identify which microorganisms are better adapted to different situations. It also allows you to monitor the microbes within a contaminated area.
References:(1) Mrozik, A., & Piotrowska-Seget, Z. (2010). Bioaugmentation as a strategy for cleaning up of soils contaminated with aromatic compounds. Microbiological Research, 165(5), 363-375.
(2) Sangwan, Naseer, Pushp Lata, Vatsala Dwivedi, Amit Singh, Neha Niharika, Jasvinder Kaur, Shailly Anand, Jaya Malhotra, Swati Jindal, Aeshna Nigam, Devi Lal, Ankita Dua, Anjali Saxena, Nidhi Garg, Mansi Verma, Jaspreet Kaur, Udita Mukherjee, Jack A. Gilbert, Scot E. Dowd, Rajagopal Raman, Paramjit Khurana, Jitendra P. Khurana, and Rup Lal. "Comparative Metagenomic Analysis of Soil Microbial Communities across Three Hexachlorocyclohexane Contamination Levels." Ed. Kelly A. Brayton. PLoS ONE 7.9 (2012): E46219. Web. 3 Sept. 2014.