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ABSTRACT: In this study, a lab-scale serial photobioreactor composed of three column reactors was constructed and continuously operated to investigate several parameters influencing photohydrogen production when using the synthetic wastewater and the anaerobic hydrogen fermentation effluents as the influents. The results indicated that better hydrogen production rate was obtained when the serial photobioreactor was operated under cellular recycling at a short HRT of 8h. The serial photobioreactor maintained high hydrogen content ca. 80% in the produced gas and 0.4× dilution ratio was the suitable ratio for hydrogen production. When the photobioreactor fed with the real wastewater (Effluent 1) containing 100 mg/L NH4Cl, Column 1 reactor successfully reduced ammonia concentration to about 60 mg/L for cell synthesis, resulting in a steady hydrogen production in the following two column reactors. The average hydrogen production rate was 205 mL-H2/L/d.
Bioresource technology 04/2011; 102(18):8350-6. · 4.25 Impact Factor
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ABSTRACT: This study used a DNA recombination method to knock out the poly-β-hydroxybutyrate (PHB) synthesis gene phbC in the photosynthetic bacterium Rhodopseudomonas palustris WP3-5. The experimental results indicated that the mutant strain Rps. palustris M23 could be successfully screened. Fluorescent observation with Nile blue staining showed no significant PHB granule accumulation in the mutant cells. Batch mode experiments using acetic acid as a carbon source revealed a 29.1% and 25.9% hydrogen gas content from M23 and WP3-5, respectively. However, this trend did not appear when using propionic acid as carbon source. Under continuous operation, the hydrogen gas content from M23 could be maintained above 72%. The average hydrogen production rates of the WP3-5 and M23 strains were 264 mL-H(2)/L/day and 457 mL-H(2)/L/day, respectively. The total biogas volume collected from M23 was 1.7 times higher than that from the wild type.
Bioresource technology 09/2010; 102(9):5418-24. · 4.25 Impact Factor
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ABSTRACT: The objectives of this research were to monitor the variations of species in mixed cultures during the enrichment period, isolate species and identify and characterize the pure 4-chlorophenol (4-CP) degrading strains from enriched mixed cultures. Strain Rhizobium sp. 4-CP-20 was isolated from the acclimated mixed culture. The DGGE result indicated that strain Rhizobium sp. 4-CP-20 was undetectable at the beginning but detectable after 2 weeks of enrichment. The optimum growth temperatures for Rhizobium sp. 4-CP-20 were both 36 degrees C using 350 mg l(-1) glucose or sodium acetate as the substrate. The optimum pH range for degrading 100 mg l(-1) 4-CP was between 6.89 and 8.20. Strain Rhizobium sp. 4-CP-20 could degrade 4-CP completely within 3.95 days, as the initial 4-CP concentration was 100 mg l(-1). If the initial 4-CP concentration was higher than 240 mg l(-1), the growth of bacterial cells and the activity of degrading 4-CP were both inhibited.
Biodegradation 07/2008; 19(3):329-36. · 2.02 Impact Factor
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ABSTRACT: Pentachlorophenol (PCP) has been used as a wood preservative for more than 100 years. The extensive use of PCP has widely contaminated soil and groundwater. PCP is toxic to living organisms. The main objective of this research was to inoculate the pure PCP-degrading bacterium strain Sphingomonas chlorophenolica PCP-1, isolated from PCP-contaminated soils, into PCP-contaminated groundwater for remediation purposes. The factors that influenced the bioremediation were explored with batch experiments using the inoculated immobilized and suspended cells as inoculation. A biological treatment system inoculated with immobilized cells was set up to estimate the microbial capability to degrade PCP. The results indicated that the suspended and immobilized cells could be inoculated into PCP-contaminated groundwater without adding other supplementary nitrogen and phosphate sources in batch conditions. Moreover, PCP decomposition was accompanied with released Cl- and decreasing pH value. The optimum HRT in the bioreactor system was 12.6h. PCP removal in the bioreactor remained stable and PCP removal efficiency was higher than 92% at this phase. Furthermore, PCP concentration in the biotreatment system effluent remained undetectable. It is possible to bioremediate PCP-contaminated groundwater using immobilized S. chlorophenolica PCP-1 cells in a bioreactor system. The proposed biological treatment system could be maintained for at least for 2 months.
Journal of Hazardous Materials 04/2008; 152(1):159-65. · 4.17 Impact Factor
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ABSTRACT: Many chlorophenols tend to persist in the environment, and they may become public health hazards. Among chlorophenols, pentachlorophenol (PCP) is a priority pollutant that has been used widely as a general biocide in commercial wood treatment. Owing to the rapid industrial growth, serious soil and water pollutions by chlorophenols has been reported in Taiwan. In this study, 10 indigenous PCP-degrading bacterial strains were isolated from a PCP-degrading mixed culture, and the potential of both the pure and mixed cultures for PCP degradation compared. Moreover, the physiological characteristics and optimum growth conditions of the PCP-degrading bacteria were investigated. One of the isolated bacterial strains with good potential for PCP degradation was characterized and identified as Sphingomonas chlorophenolica by 16S rDNA gene analysis. The result of the optimum growth temperatures revealed that this organism was a mesophile. The optimum pH for PCP removal by S. chlorophenolica was between 6.9 and 7.6. Increase in concentration of PCP has a negative effect on the biodegradation potential of S. chlorophenolica and PCP concentration above 600 mg l(-1) was inhibitory to its growth. The results of this study indicate that this S. chlorophenolica strain has a better potential for PCP degradation compared to the enriched mixed culture. The physiological characterization of the isolates also indicates the possible application of this strain for bioremediation of sites contaminated with PCP.
Chemosphere 03/2006; 62(5):709-14. · 3.21 Impact Factor
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ABSTRACT: Chlorophenols are common environmental contaminants that have been used as the major component in wide-spectrum biocides in industry and agriculture. Many chlorophenols tend to persist in the environment and may become public health hazards. This research studied the ability of the pentachlorophenol (PCP)-degrading bacterium Sphingomonas chlorophenolica to degrade and dechlorinate other chlorophenols. In addition, the characteristics of S. chlorophenolica were also investigated. When S. chlorophenolica cells were preincubated with PCP, the lag phase PCP degradation periods became shorter and the PCP concentrations that could be removed became higher. S. chlorophenolica was able to completely degrade 2,3,6-trichlorophenol (2,3,6-TCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and PCP within 38.1, 15.1, 11.8, and 11.8 h, and to release concentrations of 50.1, 60.9, 63.7, and 58.5 mg/L chloride at the same period of time. In the presence of supplementary carbon sources, the PCP removal efficiency increased with the presence of glucose or pyruvate. However, the removal efficiency of 75 mg/L 2,4-dichlorophenol did not increase with supplemental carbon sources.
Current Microbiology 10/2005; 51(3):156-60. · 1.82 Impact Factor
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ABSTRACT: 酚與氯酚化合物是環境常見的污染物，如何以對環境友善之生物處理方式去除是重要的課題；而新分類生物聚合物(polythioesters, PTEs)在2001年首度發現，其中以基因工程方式聚合之poly(3- mercaptopropionate, PMP)經研究顯示具有強大的應用價值，然因為以非自然方式合成，因此後續的分解也是值得注意的課題。本研究主軸分成兩大部分，第一部份著重於酚與氯酚化合物生物降解相關研究，首先分離相關酚與氯酚分解菌，並研究其相關生理特性；另外，接續先前研究植種生理特性詳盡瞭解之五氯酚分解菌Sphingobium chlorophenolicum PCP-1(昔為Sphingomonas chlorophenolica)復育受五氯酚污染之地下水；最後，針對五氯酚分解菌PCP-1降解基因作定性、定序與表現相關研究。研究結果顯示，經馴化後，分離出純種酚分解菌Pseudomonas resinovorans P-1與Brevibacillus sp. P-6、4-氯酚分解菌Rhizobium sp. 4-CP-20與2,4-二氯酚分解菌Burkholderia cepacia 1-3b；該些菌株都不含質體，菌株P-1與P-6的酚最高降解濃度分別為600與200 mg/l，以菌株P-1具有較高之應用潛力；菌株4-CP-20最高降解濃度為100 mg/l，最適生長溫度與降解pH分別是36℃與7.59；而菌株1-3b最高降解濃度為75 mg/l，除2,4-二氯酚外，對酚、2-氯酚與4-氯酚也具有降解能力。植種懸浮態與固定化五氯酚分解菌於生物反應槽系統復育受150 mg/l五氯酚污染地下水之結果顯示，無須再額外添加氮、磷與碳源於地下水中，最佳連續流條件為植種菌體包埋濃度為8.5 mg/l-alginate之固定化細胞於水力停留時間12.6小時下操作，在該操作條件下，出流水五氯酚濃度可維持低於偵測極限，操作時間至少可維持2個月。五氯酚分解菌之五氯酚代謝途徑經定性顯示與文獻相同，此外，亦定序出菌株S. chlorophenolicum之降解基因pcpA、pcpB、pcpC、pcpD與pcpE序列；表現五氯酚降解限制步驟之基因pcpB的結果顯示，PcpB成功以pET-23a於E. coli BL21(DE3)、C41(DE3)與Origami(DE3)pLysS菌體內表現，唯最終以inclusion body形式存在。第二主軸為突變菌株Paucimonas lemoignei之PHA depolymerase基因phaZ1、phaZ5與phaZ7，使其從具PHB (poly(3-hydroxybutyrate))水解能力改變具PMP水解能力之酵素，結果顯示基因phaZ1、phaZ5與phaZ7皆以pET系統配合不同寄主細胞成功誘導表現，其中誘導表現之PhaZ1與PhaZ5具有降解dPHB (denatured PHB)活性，可於培養基上形成透明環，基因phaZ1與phaZ5經商業化XL1-red competent cells system突變後，從各基因分別篩選15000個突變株，但都不具PMP水解能力；以UV mutation方式突變結果顯示，分別從基因phaZ1與phaZ5挑選2500與1295個突變株，但突變株同樣都不具水解PMP之能力。本研究先以傳統馴化與分離方式先行分離目標菌株，進而瞭解生理特性，進而應用菌株於生物復育上，研究顯示詳盡瞭解作用菌株生理特性後將可成功應用於生物復育上；鑑於分子生物技術於環境工程領域上日益重要，應用基因工程加以監測與改造微生物作用基因達到污染物去除目的也是一種方式，因此，研究也以基因工程方式對於作用菌株之基因進行表現研究後，進而突變基因使其改變原有功能，雖然突變結果目前無法獲得預期成果。 Chlorophenolic compounds are common environmental contaminants and they are hazardous to human being. Especially pentachlorophenol (PCP) is toxic to all forms of life since it is an oxidative phosphorylation inhibitor. Thus, removing them from environment and decreasing their toxicity is an important issue. Biological treatment is harmless environmental friendly and relative economical treated procedure. Therefore, one part of this research focused on phenol and chlorophenols (CPs) biodegradation. In this field, pure phenol and CPs degrading pure strains were enriched, isolated and characterized. Moreover, PCP-degrading strain Sphingobium chlorophenolicum PCP-1 isolated previously was applied for PCP-contaminated groundwater bioremediation, and its genes involving in PCP degradation were also identified, sequencing and expressed. From phenol and CPs acclimated mixed cultures, we isolated and identified two phenol-degrading strains (Pseudomonas resinovorans strain P-1 and Brevibacillus sp. strain P-6), one 4-CP-degrading strain (Rhizobium sp. 4-CP-20) and one 2,4-dichlorophenol (2,4-DCP) strain (Burkholderia cepacia strain 1-3b). After investigation, the optimum growth temperatures for strain P-1 and P-6 were 31°C and 39°C respectively. Strain P-1 could degrade 600 mg/l phenol completely within 57.5 hr, and the maximum degraded phenol concentration of stain P-6 was 200 mg/l within 93.1 hr. Strain P-1 showed higher applied potential than strain P-6. The optimum growth temperature and 4-CP degrading pH for strain 4-CP-20 were 36°C and 7.59, respectively. Strain 4-CP-20 could degrade 100 mg/l 4-CP completely within 3.95 days, but the bacterial growth and the 4-CP degrading activity were both inhibited while the initial 4-CP concentration was higher than 240 mg/l. The maximum 2,4-DCP degrading concentration of strain 1-3b was 75 mg/l. Strain 1-3b not only utilized 2,4-DCP but also phenol, 2-CP and 4-CP as sole carbon source. After inoculating immobilized Sphingobium cells to bioremediate PCP-contaminated groundwater with a biological treatment system, the results indicated the immobilized cells could be inoculated into PCP-contaminated groundwater without adding other supplementary nitrogen, phosphate and carbon sources. The optimum HRT in the bioreactor system was 12.6 hr. PCP removal in the bioreactor remained stable and PCP removal efficiency was higher than 92% at this phase, and PCP concentration in the biotreatment system effluent remained undetectable. It is possible to bioremediate PCP-contaminated groundwater using immobilized Sphingobium cells in a bioreactor system. The proposed biological treatment system could be maintained for at least for two months. Besides, PCP metabolic pathway of strain Sphingomonas chlorophenolica PCP-1 was the same with previous study, and its PCP-degrading genes pcpA, pcpB, pcpC, pcpD and pcpE were sequenced. Gene pcpB was successfully expressed with pET-system, but the expressed protein was aggregated into inclusion body form.Another part of this study was concerned with recalcitrant biopolymer biodegradation. Polythioesters (PTEs) are the newest eighth class of biopolymers, and the first PTEs member was identified in 2001. Among PTEs, homopolymer poly(3-mercaptobutyrate) (PMP) synthesized using non-natural pathway displays good potential for application. However, before its extensive utilization, the PMP biodegradability has to be addressed more throughoutly. In this field, PHA depolymerase genes (phaZ1, phaZ5 and phaZ7) from strain Paucimonas lemoignei were identified, sequenced, expressed and mutated. Our result demonstrated that gene phaZ1 and phaZ5 of strain P. lemoignei could be expressed by strain E. coli and pET-23a system and the expressed proteins contained activities of degrading dPHB granules. After mutation with XL1-red competent cells system and UV light, no mutant containing PMP degrading ability was successfully screened. The third gene phaZ7 also could be expressed, but its nPHB degrading ability was not detectable.According to all results mentioned above, we can summarize that functional strains could be applied successfully for bioremediation after appropriate enrichment and detailed characterization. Moreover, basing on the role of molecular biotechnology on environmental engineering becomes gradually important. To approach recalcitrant compounds biodegradation, sometimes genomic engineering methods could be powerful tools and the background of functional genes in functional strain also must be investigated carefully. We tried to change the substrate specificity of gene phaZ using molecular biotechnological methods. However, the results were not so successful.
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ABSTRACT: The objectives of this research were to isolate pure phenol-degrading strains from enriched mixed cultures, monitoring the variations of species during the enrichment period. Two strains were isolated from the acclimated mixed culture. They were identified as Pseudomonas resinovorans strain P-1 and Brevibacillus sp. strain P-6. DGGE indicated that strain P. resinovorans appeared at the beginning, and maintained well during the enrichment period. The second strain, Brevibacillus sp., did not appear in the initial stage, but showed up after 2 weeks of enrichment. The optimum growth temperatures for P. resinovorans and Brevibacillus sp. were 31 and 39 °C, respectively. P. resinovorans could degrade phenol completely within 57.5 h, when the initial phenol concentration was lower than 600 mg l−1. If the initial phenol concentration was lower than 200 mg l−1, Brevibacillus sp. could remove phenol completely within 93.1 h. It was obvious that the phenol-degrading ability of P. resinovorans was much better than that of Brevibacillus sp. The metabolic pathway for P. resinovorans phenol degradation was assigned to the meta-cleavage activity of catechol 2,3-dioxygenase.
International Biodeterioration & Biodegradation.
