IJLSSR,VOLUME 3, ISSUE 1, JANUARY 2017 : 828-831

    
Research Article (Open Access)

Effect of Physical Parameters and Amino acids on the Oil degradation Activity of Bacteria Isolated from Oil Contaminated Sites

Praveen Reddy P1, Ravi A2*
1Research Scholar, Department of Microbiology, Acharya Nagarjuna University, Guntur, AP, India
2Lecturer, Department of Biotechnology, Vivekananda Degree & PG College, Karimnagar, Telangana, India

*Address for Correspondence: Mr. A. Ravi, Lecturer, Department of Biotechnology, Vivekananda Degree & PG College, Karimnagar, Telangana, India
Received: 12 November 2016/Revised: 05 December 2016/Accepted: 27 December 2016

ABSTRACT- Mechanical workshops release huge levels of used engine oil into the surroundings. Many mechanical workshops do not have proper disposal mechanisms and eventually used engine oil reaches the surrounding soil. The hydrocarbons present in used engine oil damage the environment and human health. There are microbes in nature which have the ability to degrade the used engine oil. Such microbes can be isolated and used for the biodegradation of hazardous and recalcitrant hydrocarbons occurring in used engine oil. The present study deals with the four used engine oil degrading bacterial species isolated from oil contaminated sites of mechanical workshops. The bacterial species were Bacillus, Acinetobacter, Pseudomonas and Micrococcus. The optimum pH and temperature on the oil degradation activity of bacterial species were determined. In addition, effect of various amino acids on the oil degradation ability of these bacterial species was studied and best amino acid for oil degrading activity was determined. All the four bacterial species exhibited highest oil degrading activity at pH 7.0. The optimal temperature required for maximum oil degradation activity by Bacillus and Acinetobacter species was 330C and 350C respectively. At 310C Pseudomonas and Micrococcus species had shown maximum oil degradation activity. All the bacterial species had shown enhanced oil degradation activity in methionine supplemented medium. Bacillus species was found to be efficient among all the four species.
Key-Words- Mechanical workshops, Used engine oil, Oil degrading bacteria, Optimum, pH, Temperature, Amino acids

INTRODUCTION- Used engine oil causes potential damage to the environment. Engine oil is filled in the motor vehicles for the functioning of engine. The engine oil is combusted during its usage. At intervals used engine oil is replaced with fresh engine oil. The used engine oil is disposed into the environment from mechanical workshops. Used engine oil consists of hazardous aliphatic, polyaromatic, organosulfur compounds and heavy metals [1]. These compounds and heavy metals are mutagenic and carcinogenic to humans [2]. Nearly six million tons of crude oil is disposed into the environment from various sources [3]. Many of the organic compounds present in used engine oil are recalcitrant. The soils polluted with used engine oil contain immobilized minerals, such soils lose water holding capacity, permeability and binding ability resulting in loss of soil fertility [4]. There are microbes which can degrade the hazardous organic compounds occurring in used engine oil into non-toxic simple molecules. This process is known as biodegradation and the microbes are called biodegrading microbes. The biodegradation process is eco-friendly and simple [5]. Microbes which can degrade oil hydrocarbons include Flavobacterium, Pseudomonas, Arthrobacter, Alcaligenes etc., [6]. In the present work four bacterial species were isolated from oil contaminated sites of mechanical workshops of Kaman region of Karimnagar town, Telangana, India and identified till genus level. The bacteria were identified as Bacillus, Acinetobacteria, Pseudomonas and Micrococcus species. All the four isolated bacterial species were able to degrade the used engine oil by utilizing the hydrocarbons of used engine oil as carbon source. The present paper deals with the study of effect of physical parameters (pH and temperature) and various amino acids on the biodegradation ability of these four bacterial species. The physical parameters required for oil biodegradation activity were optimized and best amino acid source for enhanced oil degradation activity was determined.

MATERIALS AND METHODS-
The present work was carried out in the Department of Biotechnology, Vivekananda Degree and PG College, Karimnagar for a period of six months. Oil degradation activity studies were performed using minimal salt (MS) medium with composition, 0.2 g (NH4)2SO4, 0.1 g MgSO4.7H2O, 0.076 g Ca(NO3)2.4H2O and 40 mM phosphate buffer per liter distilled water [7]. The minimal salt medium is supplemented with 5% used engine oil (obtained from light motor vehicles mechanical workshops). The hydrocarbons (organic compounds) present in used engine oil serves as sole carbon source for the bacteria.

Inoculum preparation- Each bacterial culture was inoculated into 10 ml of MS medium with 5% used engine oil and incubated overnight at 300C. After incubation the culture was centrifuged at 3500 rpm to get cell pellet. After washing each cell culture’s pellet was inoculated into MS medium with 5% used engine oil and grown till the optical density of each culture broth was 1 at 600 nm. One ml of such each bacterial culture serves as inoculum source [8].

Optimization of Physical parameters- Each bacterial culture is grown at pH 5.0, 6.0, 7.0 & 8.0 at 300C to determine the optimum pH for maximum oil degradation activity. Then each bacterial culture is grown at its optimum pH within a range of temperatures 300C to 400C to determine the optimum temperature for oil degradation process.

Determination of optimum amino acid source- Each bacterium was grown at its optimum pH and temperature in different amino acids. Each amino acid concentration supplemented in the medium was 1mg/ml [9]. The amino acids used for the study were Proline (Pro), Alanine (Ala), Phenylalanine (Phe), Tyrosine (Tyr), Arginine (Arg), Lysine (Lys), Cysteine (Cys), Methionine (Met) and Glutamine (Gln). Then optimum amino acid source required for each bacterium was determined.
For all the studies 1ml of each bacterial culture was added to 100 ml of MS medium with 5% used engine oil and incubated in shakers. The growth was measured in terms of optical density (at 600 nm) of biomass of each bacterial culture after 2 weeks. The growth each bacterial culture is proportional to the oil degradation activity. More growth is an indication of higher oil degradation activity. All the studies were made in triplicates and standard deviation was calculated for each record.

RESULTS AND DISCUSSION-
The four bacterial species, Bacillus, Acinetobacter, Pseudomonas and Micrococcus isolated from oil contaminated sites of mechanical workshops were grown in MS medium with used engine oil as sole carbon source. The bacteria were grown at various pH and temperatures to determine the optimal physical parameters for the degradation of used engine oil. The optimal pH for the oil degradation activity (growth) of all the four bacterial species was pH 7.0 (Table 1). Bacillus subtilis had shown maximum growth & protease activity and Acinetobacter sp. ISTPCP-3 exhibited maximum growth at pH 7.0 [10-11]. Similarly pH 7.0 was found to be optimum for the growth of Pseudomonas marginalis and Micrococcus species [12-13].
The optimal temperature required for maximum oil degradation activity by Bacillus and Acinetobacter species was 330C and 350C respectively (Table 2). Bacillus subtilis KC3 had shown maximum growth at 330C [14] and most of the Acinetobacter species show highest growth between temperatures 33-350C [15]. The optimal temperature for Pseudomonas and Micrococcus species was found to be 310C (Table 2). All the bacterial species were isolated from mesophilic environment and hence, the optimum temperature for all the isolated species is around 30oC.
Maximum oil degradation activity was recorded in all the four bacterial species when used engine oil containing medium was amended with Methionine [9] followed by cysteine. All the four bacterial species had shown similar response to Methionine and Cysteine and varied response towards remaining amino acids (Table 3). The order of used engine oil degradation activity by the four bacterial species in response to various amino acids is given below:

Bacillus: Methionine > Cysteine > Glutamine > Proline > Alanine > Tyrosine > Arginine > Phenylalanine > Lysine

Acinetobacter: Methionine > Cysteine > Glutamine > Proline > Alanine > Arginine > Tyrosine > Phenylalanine > Lysine

Pseudomonas: Methionine > Cysteine > Glutamine > Proline > Alanine > Tyrosine > Arginine > Lysine > Phenylalanine

Micrococcus: Methionine > Cysteine > Proline > Glutamine > Alanine > Tyrosine > Phenylalanine > Arginine > Lysine

Table 1: Effect of pH on oil biodegradation activity of bacterial species

S. No. Bacterial Species OD values at 600 nm at different pH conditions
5.0 6.0 7.0 8.0
1 Bacillus 0.90 ± 0.05 1.20 ± 0.09 1.41 ± 0.05 1.10 ± 0.12
2 Acinetobacter 0.61 ± 0.12 0.64 ± 0.09 0.71 ± 0.08 0.62 ± 0.05
3 Pseudomonas 0.84 ± 0.05 1.00 ± 0.05 1.26 ± 0.08 0.98 ± 0.09
4 Micrococcus 0.72 ± 0.08 0.91 ± 0.05 1.10 ± 0.09 0.87 ± 0.09

Table 2: Effect of temperature on oil biodegradation activity of bacterial species
S. No. Bacterial Species OD at 600 nm at different temperatures
300 310 320 330 340 350 360 370 380 390 400
1 Bacillus 1.43 ± 0.12 1.49 ± 0.05 1.56 ± 0.05 1.63 ± 0.09 1.59 ± 0.05 1.44 ± 0.09 1.38 ± 0.05 1.30 ± 0.09 1.22 ± 0.08 1.03 ± 0.08 0.92 ± 0.05
2 Acinetobacter 0.70 ± 0.08 0.77 ± 0.12 0.84 ± 0.05 0.91 ± 0.08 0.98 ± 0.12 1.18 ± 0.05 1.10 ± 0.08 1.06 ± 0.05 1.03 ± 0.05 1.00 ± 0.12 0.97 ± 0.12
3 Pseudomonas 1.19 ± 0.09 1.28 ± 0.05 1.11 ± 0.09 1.03 ± 0.05 0.96 ± 0.09 0.89 ± 0.12 0.80 ± 0.08 0.72 ± 0.05 0.67 ± 0.09 0.61 ± 0.12 0.55 ± 0.08
4 Micrococcus 1.06 ± 0.05 1.11 ± 0.08 1.01 ± 0.08 0.97± 0.05 0.91 ± 0.08 0.84± 0.08 0.77± 0.08 0.69 ± 0.08 0.62± 0.05 0.57± 0.05 0.50 ± 0.08

Table3: Effect of various amino acids on oil biodegradation activity of bacterial species
S. No. Bacterial Species OD at 600 nm of bacterial broth cultures in various amino acids with concentration 1mg/ml (bacteria grown at their respective optimal pH and temperatures)
Pro Ala Phe Tyr Arg Lys Cys Met Gln
1 Bacillus 1.73 ± 0.12 1.69 ± 0.09 1.59 ± 0.09 1.66 ± 0.05 1.62 ± 0.05 1.57 ± 0.09 1.80 ± 0.05 1.84 ± 0.12 1.76 ± 0.09
2 Acinetobacter 1.34 ± 0.05 1.31 ± 0.12 1.22 ± 0.12 1.25 ± 0.09 1.28 ± 0.12 1.20 ± 0.12 1.40 ± 0.14 1.44 ± 0.09 1.37 ± 0.05
3 Pseudomonas 1.47 ± 0.08 1.44 ± 0.09 1.30 ± 0.08 1.40 ± 0.16 1.37 ± 0.09 1.33 ± 0.16 1.54 ± 0.05 1.59 ± 0.12 1.50 ± 0.05
4 Micrococcus 1.40 ± 0.09 1.31 ± 0.05 1.24 ± 0.05 1.28 ± 0.05 1.20± 0.09 1.15 ± 0.08 1.46 ± 0.12 1.50 ± 0.05 1.36 ± 0.12

All the bacterial species oil degrading activity was enhanced when they were grown in amino acid supplemented media. No amino acid had been decreased the oil biodegra dation activity. The Bacillus species was found to be efficient oil degrading species when compared to other three oil degrading bacterial species [16].

CONCLUSION- Used engine oil is disposed from various mechanical workshops reach the surrounding environment. Some hydrocarbons present in used engine oil are recalcitrant, hazardous and cause deleterious effects to environment and human health. These hazardous hydrocarbons present in used engine oils can be degraded by microbes to clean up the environment. In the present work used engine oil degrading ability of four bacterial species viz., Bacillus, Acinetobacter, Pseudomonas and Micrococcus isolated from oil contaminated sites of mechanical workshops of Kaman area of Karimnagar town under different parameters was studied. The bacteria were grown in MS medium with 5% used engine oil to study their oil degradation activity under different parameters. The physical parameters pH and temperature for each bacterium were optimized and best amino acid to be amended to increase the oil degrading activity was determined. Bacillus species was found to be efficient among all the four species. Further these bacteria can be identified till species level, genetically improved and used for bioremediation. As Bacillus found to be the efficient species among the four, more emphasis can be made on its oil degradation activity.

ACKNOWLEDGMENT- We are extremely thankful to the Head, Department of Biotechnology, Vivekananda Degree & PG College, Karimnagar, Telangana, India for permitting us to use the laboratory to carry out the work related to this paper. We are also thankful to Principal, Administrative officer and staff for their support. Finally we thank Head, Department of computer science for permitting us to use the computer lab and internet during the preparation of the paper.

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How to cite this article:
Reddy PP, Ravi A: Value Effect of Physical Parameters and Amino acids on the Oil degradation Activity of Bacteria Isolated from Oil Contaminated Sites. Int. J. Life. Sci. Scienti. Res., 2017; 3(1): 828-831. DOI:10.21276/ijlssr.2017.3.1.13
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