Abstract:A bacterial strain capable of growing on propachlor (2-chloro-N-isopropylacetanilide) was isolated from soil by using enrichment and isolation techniques. The strain isolated, designated GCH1, was classified as a member of the genus Pseudomonas. Washed-cell suspensions of strain GCH1 accumulated N-isopropylacetanilide, acetanilide, acetamide, and catechol. Pseudomonas strain GCH1 grew on propachlor with a generation time of 4.2 h and a rate of substrate utilization of 1.75 ؎ 0.15 mol h ؊1 . Gene expression did… Show more
“…Characterization studies of the isolate from these experiments, as well as of those by other researchers, indicate that bacteria belonging to the genus pseudomonas are gram negative, rodshaped, highly oxidative and metabolically versatile, able to degrade aromatic hydrocarbons, oil, petroleum products and pesticides (Hashmi, 2000;Martin, et al, 2000;Ramanathan and Lalithakumari, 1999;Lee, et al, 1998;Ramos, et al, 1995;Maloney, et al, 1988).…”
Section: Identification and Characterization Of Bacterial Isolatementioning
ABSTRACT:The biodegradation of Cypermethrin (20 to 125 mg/L) in an effluent using batch activated sludge was studied. Degradation was found to occur to a great extent only in the presence of Pseudomonas (IES-Ps-1) culture. Under aerobic conditions using mechanical aerators, Cypermethrin (20 mg/L) was almost completely degraded in just over 48 h at ambient temperature. Further loading of organic compound in subsequent experiments demonstrated that IES-PS-1was capable to degrade 82 % Cypermethrin at 40 mg/L dose in approximately 48 h. When the concentration was increased to 80 mg/L, 50% degradation of this compound was observed. Over this time period the cells could utilize only 17 % of Cypermethrin when it was given 125 mg/L, respectively. These findings indicate that increased concentration of Cypermethrin has a marked effect on biodegradation performance of IES-Ps-1 with a modest increased in the duration of lag phase, but did not lead to complete inhibition or cell death. These results proved that IES-Ps-1 is responsible for Cypermethrin degradation. Such finding may be useful in designing a scale-up in situ or on-site hazardous waste bioremediation process for field application.
“…Characterization studies of the isolate from these experiments, as well as of those by other researchers, indicate that bacteria belonging to the genus pseudomonas are gram negative, rodshaped, highly oxidative and metabolically versatile, able to degrade aromatic hydrocarbons, oil, petroleum products and pesticides (Hashmi, 2000;Martin, et al, 2000;Ramanathan and Lalithakumari, 1999;Lee, et al, 1998;Ramos, et al, 1995;Maloney, et al, 1988).…”
Section: Identification and Characterization Of Bacterial Isolatementioning
ABSTRACT:The biodegradation of Cypermethrin (20 to 125 mg/L) in an effluent using batch activated sludge was studied. Degradation was found to occur to a great extent only in the presence of Pseudomonas (IES-Ps-1) culture. Under aerobic conditions using mechanical aerators, Cypermethrin (20 mg/L) was almost completely degraded in just over 48 h at ambient temperature. Further loading of organic compound in subsequent experiments demonstrated that IES-PS-1was capable to degrade 82 % Cypermethrin at 40 mg/L dose in approximately 48 h. When the concentration was increased to 80 mg/L, 50% degradation of this compound was observed. Over this time period the cells could utilize only 17 % of Cypermethrin when it was given 125 mg/L, respectively. These findings indicate that increased concentration of Cypermethrin has a marked effect on biodegradation performance of IES-Ps-1 with a modest increased in the duration of lag phase, but did not lead to complete inhibition or cell death. These results proved that IES-Ps-1 is responsible for Cypermethrin degradation. Such finding may be useful in designing a scale-up in situ or on-site hazardous waste bioremediation process for field application.
“…These substrate inhibition difficulties can be overcome by strategies such as cell immobilization to protect microbial cells against phenol toxicity (24). Aerobic granulation is a recently reported form of cell immobilization technology that is attracting considerable research attention (27,38).…”
Aerobic granules are self-immobilized aggregates of microorganisms and represent a relatively new form of cell immobilization developed for biological wastewater treatment. In this study, both culture-based and cultureindependent techniques were used to investigate the bacterial diversity and function in aerobic phenol-degrading granules cultivated in a sequencing batch reactor. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes demonstrated a major shift in the microbial community as the seed sludge developed into granules. Culture isolation and DGGE assays confirmed the dominance of -Proteobacteria and high-G؉C gram-positive bacteria in the phenol-degrading aerobic granules. Of the 10 phenol-degrading bacterial strains isolated from the granules, strains PG-01, PG-02, and PG-08 possessed 16S rRNA gene sequences that matched the partial sequences of dominant bands in the DGGE fingerprint belonging to the aerobic granules. The numerical dominance of strain PG-01 was confirmed by isolation, DGGE, and in situ hybridization with a strain-specific probe, and key physiological traits possessed by PG-01 that allowed it to outcompete and dominate other microorganisms within the granules were then identified. This strain could be regarded as a functionally dominant strain and may have contributed significantly to phenol degradation in the granules. On the other hand, strain PG-08 had low specific growth rate and low phenol degradation ability but showed a high propensity to autoaggregate. By analyzing the roles played by these two isolates within the aerobic granules, a functional model of the microbial community within the aerobic granules was proposed. This model has important implications for rationalizing the engineering of ecological systems.
“…Cell immobilization has been employed for biological removal of pesticides due to the possibility of maintaining catalytic activity over long periods of time (Richins et al, 2000;Chen & Georgiou 2002;Martin et al, 2000). Cell immobilization consists of restricting cellular mobility within a defined space, thereby retaining catalytic activity.…”
Section: The Immobilization Of Microorganisms For Massive Pesticides mentioning
confidence: 99%
“…Immobilization of microorganisms has been applied in many areas including wastewater treatment and remediation of toxic chemicals from this technique generally provides several advantages over cultures using suspended cells that include greater cellular content in the support, enhanced cellular viability (weeks or months) and greater tolerance to high concentrations of pollutants. However, the main limitations to this method are low oxygen diffusion and interference by the materials used as the support (Martin et al, 2000;Georgiou et al, 2005). Encapsulation and biofilm formation methods are commonly used in environmental contexts.…”
Section: The Immobilization Of Microorganisms For Massive Pesticides mentioning
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