Bioremediation Author’s profile Hi, my name is Guanchen Zhu. I’m an undergraduate student in biomedical science and this is my last year of study. When mentioned about the crude oil spilling, I always feel that’s far away from me. However the spillage of petroleum happened a few years ago in my home town impressed me especially when I saw those beautiful and crowded beach suddenly became such a cold and cheerless place which covered with black, sticky and smelly oil… It’s said that even though most of the oil has been removed, the remaining could require more than a decade to recover. So I’m so worried about it and looking for a way that could solve it faster. Could this method be biodegradation? ure/2010/07/oil_spill_in_dalian_ china.html Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Background Petroleum is a mixture of hydrocarbons of various molecular weights and other organic compounds. According to their carbon structures, the compositions can be divided into alkanes, cycloalkanes, aromatics and asphaltene and most of them are saturated hydrocarbons alkanes and cycloalkanes. Bioremediation is an acceleration of the natural fate of oil pollutants and hence a natural or ‘green solution’ to the problem of oil pollutants that causes minimal ecological effects (Ronald, 1995). Bioremediation is recognized as an efficient, economic and versatile alternative to physicochemical treatment. During the last decade, bioremediation has attracted much attention and new strains with faster degrading has been identified (Zhang et al, 2010) However even though low-molecular-weight molecules are found to be readily degraded by many micro-organisms, long-chain alkanes and polycyclic aromatic hydrocarbons (PAH) are generally considered to be only slightly biodegradable due to their higher hydrophobicity (Kanaly and Harayama, 2000). Since then, exploiting more efficient micro-organisms has become central to petroleum microbiology. Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Executive summary In both of the papers, new strains were found and isolated which has greater capability of degrading petroleum. Degradation of high-molecular-weight molecules in the petroleum and the strains with wide range of degrading diversity and efficiency are currently the central problems in petroleum remediation. Pseudomonas aeruginosa DQ8 is able to degrade n-alkanes and polycyclic aromatics. While the noval Dietzia strain is capable of degrading wide range of petroleum hydrocarbons(C6-C40) Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Degradation of n-alkanes and polycyclic aromatic hydrocarbons in petroleum by a newly isolated Pseudomonas aeruginosa DQ8 Zhengzhi Zhang, Zhaowei Hou, Chunyu Yang, Cuiqing Ma, Fei Tao, Ping Xu In the present study, the gram negative pseudomonas aeruginosa strain, designated as DQ8, was isolated from oil-contaminated soils. The results of capability of degradation showed that DQ8 is able to significantly degrade the crude oil in MBSM containing 10% of crude oil, a part of the crude oil when MBSM was supplemented with 25% crude oil in 10 days. The degradation activities were confirmed by the experiments of degrading pure n-alkanes and PAH which both gave the positive results. In this research, the end product of metabolic pathway of n-alkane were octadecanoic acid and hexadecanoic acid. The end product of metabolic pathway of PAH were 9-fluorenol, 9-fluorenone, 3-propanoic acid, 2- acetic acid and 1- indanone. These results indicated that this newly isolated P. aeruginosa DQ8 could grow with crude oil as the sole carbon and energy source and degrade the oil efficiently. Two major components of the crude oil, n-alkane and PAHs were both tested to be degraded by P. aeruginosa DQ8. Therefore, P. aeruginosa DQ8 may be of great significance of bioremediation of petroleum pollution. Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Degradation of petroleum hydrocarbons (C6–C40) and crude oil by a novel Dietzia strain Xingbiao Wang, Changqiao Chi, Yong Nie, Yueqin Tang, Yan Tan, Gang Wu, Xiaolei Wu. A novel strain, DQ b was selected and isolated from the oil-pollutated waster water due to its good ability of alkane degradation in the cultivation. In the following study of this strain, growth of DQ b was observed in the medium with different pure carbon sources. The result was shown in Table 1. When n- alkanes (C6-C40) and other compounds were tested as the sole carbon sources for strain DQ b, growth was observed in all cases even though the growth under some of the carbon sources was slower ( in Table 2). Also, a different alkane utilization pattern was observed. Thus, this novel Dietzia strain was demonstrated able to grow and utilize alkane from C6-C40 and aromatic compounds as the sole carbon sources. The unique pattern of alkane utilization also suggests a novel long- chain alkane oxidation pathway exists. Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference Table 1

Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Comparison of two papers P. aeruginosa DQ8 (Zhang et al.) and DQ b (Wang et al.) isolated were both capable of degrading long-chain hydrocarbons. The ability of growing under different molecular weight of carbon sources was tested and demonstrated in Wang. But there was no data supports capability of degrading wide range of alkanes in Zhang even though it was mentioned. The efficiency of degradation was tested with both pure supplements and crude oil. Both of the strains were demonstrated to be able to degrade long-chain hydrocarbons which were considered as the most difficult part of bioremediation. Lastly, the metabolic pathway of the p.aeruginosa DQ8 was described but the metabolic pathway of DQ b was not clarified due to the purpose of a novel pathway. Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Critical comment Both of the scientific work were done in high quality. Controls were properly used and blanks were subtracted. In Zhang et al, the authors claimed that P.aeruginosa DQ8 was able to degrade wide rage of petroleum compounds. Even though authors mentioned about the short-chained hydrocarbons were completely degraded, no detailed data was provided to prove the diversity of the capability of degradation. Perhaps this was not the important point of the paper. In Wang et al. the end product was not tested and the metabolic pathway they proposed was not a ordinary pathway. We could not predict the end product of DQ b’s metabolism. Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

Personal comment Petroleum spill causes disastrous damage to the local environment, marine ecology and fishery. Due to uncertain factors, accidents could not always be avoided. Thus efficient and eco-friendly methods of cleaning up the pollutants is very important and necessary for us. The other issue I considered was that if the end product of the bioremediation would cause another environmental issue because what I noticed is that the most of the end products were acids. Will they again disrupt the ecology further? Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference

1.Atlas, R.M. (1995). Bioremediation of Petroleum Pollutants. International Biodeterioration & Biodegradation (1995) Zhengzhi Zhang, Zhaowei Hou, Chunyu Yang, Cuiqing Ma, Fei Tao, Ping Xu (2010). Degradation of n-alkanes and polycyclic aromatic hydrocarbons in petroleum by a newly isolated Pseudomonas aeruginosa DQ8. Bioresource Technology 102 (2011) Xingbiao Wang, Changqiao Chi, Yong Nie, Yueqin Tang, Yan Tan, Gang Wu, Xiaolei Wu (2011)Degradation of petroleum hydrocarbons (C6–C40) and crude oil by a novel Dietzia strain. Bioresource Technology 102 (2011) Author’s profile Background Executive Summary Paper 1 ( Zhang et al.) Paper 1 ( Zhang et al.) Paper 2 (Wang et al.) Paper 2 (Wang et al.) Table 2 Comparison Critical comment Personal comment Reference