Outline
- Abstract
- 1. Introduction
- 2. Enzymes
- 2.1. Introduction to Enzymes
- 2.2. Enzyme Nomenclature
- 2.3. Enzyme Classification
- 3. Microbial Enzymes in Bioremediation
- 3.1. Microbial Oxidoreductases
- 3.1.1. Microbial Oxygenases
- 3.1.2. Monooxygenases
- 3.1.3. Microbial Dioxygenases
- 3.2. Microbial Laccases
- 3.3. Microbial Peroxidases
- 3.3.1. Classification of Peroxidase Enzymes
- 4. Microbial Hydrolytic Enzymes
- 4.1. Microbial Lipases
- 4.2. Microbial Cellulases
- 4.3. Microbial Proteases
- References
رئوس مطالب
- چکیده
- 1.مقدمه
- 2. آنزیم ها
- 2.1 مقدمه ای بر آنزیم ها
- 2.2 فهرست نام های آنزیم ها
- 3.2 شناسایی یک آنزیم خاص
- 3. آنزیم های میکروبی در اصلاح زیستی
- 3.1 اکسیدورداکتاز های میکروبی
- 3.1.1 اکسیژناز میکروبی
- 3.1.2 مونوکسید نازها
- 3.1.3 دی اکسیژناز میکروبی
- 3.2 لاکاز های میکروبی
- 3.3 پروکسیدهای میکروبی
- 3.3.1 دسته بندی آنزیم های پراکسیداز
- 4. آنزیم های هیدرولیتیک میکروبی
- 4.1 لیپازهای میکروبی
- 4.2 سلولز میکروبی
- 4.3 پروتئاز میکروبی
Abstract
A large number of enzymes from bacteria, fungi, and plants have been reported to be involved in the biodegradation of toxic organic pollutants. Bioremediation is a cost effective and nature friendly biotechnology that is powered by microbial enzymes. The research activity in this area would contribute towards developing advanced bioprocess technology to reduce the toxicity of the pollutants and also to obtain novel useful substances. The information on the mechanisms of bioremediation-related enzymes such as oxidoreductases and hydrolases have been extensively studied. This review attempts to provide descriptive information on the enzymes from various microorganisms involved in the biodegradation of wide range of pollutants, applications, and suggestions required to overcome the limitations of their efficient use.
4. Microbial Hydrolytic Enzymes
The pollution of soil and water by industrial chemicals and petroleum hydrocarbons is a serious problem of the modern world. Due to their extensive use, they are found as environmental contaminants in numerous aquatic and terrestrial ecosystems. The use of bioremediation technologies for removing these contaminants provides a safe and economic alternative to commonly used physical-chemical treatment. Bacterial activity is the major process involved in the hydrolysis of organic pollutants (Table 1). Extracellular enzyme activity is a key step in degradation and utilization of organic polymers, since only compounds with molecular mass lower than 600 daltons can pass through cell pores [46].
Table 1: Industrial applications of microbial enzymes.
Hydrolytic enzymes disrupt major chemical bonds in the toxic molecules and results in the reduction of their toxicity. This mechanism is effective for the biodegradation of oil spill and organophosphate and carbamate insecticides. Organochlorine insecticides such as DDT and heptachlor are stable in well-aerated soil but readily degrade in anaerobic environments [12, 46, 47]. Hydrolases also catalyze several related reactions including condensations and alcoholysis. The main advantages of this enzyme class are ready availability, lack of cofactor stereoselectivity, and tolerate the addition of water-miscible solvents. Hydrolases belong to group 3 of enzyme class and may further be classified according to the type of bond hydrolyzed [48].
Extracellular hydrolytic enzymes such as amylases, proteases, lipases, DNases, pullulanase, and xylanases have quite diverse potential usages in different areas such as food industry, feed additive, biomedical sciences, and chemical industries [49]. The hemicellulase, cellulase, and glycosidase are of much importance due to its application in biomass degradation [39].