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1.
Shaikh A. Razzak Saad Aldin M. Ali Mohammad M. Hossain Alexis Nzila Mouanda 《Bioprocess and biosystems engineering》2016,39(11):1651-1658
The present research is focused on cultivation of microalgae strain Chlorella vulgaris for bio-fixation of CO2 coupled with biomass production. In this regard, a single semi-batch vertical tubular photobioreactor and four similar photobioreactors in series have been employed. The concentration of CO2 in the feed stream was varied from 2 to 12 % (v/v) by adjusting CO2 to air ratio. The amount of CO2 capture and algae growth were monitored by measuring decrease of CO2 concentration in the gas phase, microalgal cell density, and algal biomass production rate. The results show that 4 % CO2 gives maximum amount of biomass (0.9 g L?1) and productivity (0.118 g L?1 day?1) of C. vulgaris in a single reactor. In series reactors, average productivity per reactor found to be 0.078 g L?1 day?1. The maximum CO2 uptake for single reactor also found with 4 % CO2, and it is around 0.2 g L?1 day?1. In series reactors, average CO2 uptake is 0.13 g L?1 day?1 per reactor. TOC analysis shows that the carbon content of the produced biomass is around 40.67 % of total weight. The thermochemical characteristics of the cultivated C. vulgaris samples were analyzed in the presence of air. All samples burn above 200 °C and the combustion rate become faster at around 600 °C. Almost 98 wt% of the produced biomass is combustible in this range. 相似文献
2.
Zhong-Yu You Zhi-Qiang Liu Yu-Guo Zheng 《Applied microbiology and biotechnology》2014,98(4):1671-1680
A carbonyl reductase (SCR2) gene was synthesized and expressed in Escherichia coli after codon optimization to investigate its biochemical properties and application in biosynthesis of ethyl (S)-4-chloro-3-hydroxybutanoate ((S)-CHBE), which is an important chiral synthon for the side chain of cholesterol-lowering drug. The recombinant SCR2 was purified and characterized using ethyl 4-chloro-3-oxobutanoate (COBE) as substrate. The specific activity of purified enzyme was 11.9 U mg?1. The optimum temperature and pH for enzyme activity were 45 °C and pH 6.0, respectively. The half-lives of recombinant SCR2 were 16.5, 7.7, 2.2, 0.41, and 0.05 h at 30 °C, 35 °C, 40 °C, 45 °C, and 50 °C, respectively, and it was highly stable in acidic environment. This SCR2 displayed a relatively narrow substrate specificity. The apparent K m and V max values of purified enzyme for COBE are 6.4 mM and 63.3 μmol min?1 mg?1, respectively. The biocatalytic process for the synthesis of (S)-CHBE was constructed by this SCR2 in an aqueous–organic solvent system with a substrate fed-batch strategy. At the final COBE concentration of 1 M, (S)-CHBE with yield of 95.3 % and e.e. of 99 % was obtained after 6-h reaction. In this process, the space-time yield per gram of biomass (dry cell weight, DCW) and turnover number of NADP+ to (S)-CHBE were 26.5 mmol L?1 h?1 g?1 DCW and 40,000 mol/mol, respectively, which were the highest values as compared with other works. 相似文献
3.
Vojtech Kouba P. Widiayuningrum L. Chovancova P. Jenicek J. Bartacek 《Journal of industrial microbiology & biotechnology》2016,43(7):965-975
Energy consumption of municipal wastewater treatment plants can be reduced by the anaerobic pre-treatment of the main wastewater stream. After this pre-treatment, nitrogen can potentially be removed by partial nitritation and anammox (PN/A). Currently, the application of PN/A is limited to nitrogen-rich streams (>500 mg L?1) and temperatures 25–35 °C. But, anaerobically pretreated municipal wastewater is characterized by much lower nitrogen concentrations (20–100 mg L?1) and lower temperatures (10–25 °C). We operated PN/A under similar conditions: total ammonium nitrogen concentration 50 mg L?1 and lab temperature (22 °C). PN/A was operated for 342 days in a 4 L moving bed biofilm reactor (MBBR). At 0.4 mg O2 L?1, nitrogen removal rate 33 g N m?3 day?1 and 80 % total nitrogen removal efficiency was achieved. The capacity of the reactor was limited by low AOB activity. We observed significant anammox activity (40 g N m?3 day?1) even at 12 °C, improving the applicability of PN/A for municipal wastewater treatment. 相似文献
4.
Haydée De Clippeleir Siegfried E. Vlaeminck Fabian De Wilde Katrien Daeninck Mariela Mosquera Pascal Boeckx Willy Verstraete Nico Boon 《Applied microbiology and biotechnology》2013,97(23):10199-10210
Energy-positive sewage treatment can be achieved by implementation of oxygen-limited autotrophic nitrification/denitrification (OLAND) in the main water line, as the latter does not require organic carbon and therefore allows maximum energy recovery through anaerobic digestion of organics. To test the feasibility of mainstream OLAND, the effect of a gradual temperature decrease from 29 to 15 °C and a chemical oxygen demand (COD)/N increase from 0 to 2 was tested in an OLAND rotating biological contactor operating at 55–60 mg NH4 +–N?L?1 and a hydraulic retention time of 1 h. Moreover, the effect of the operational conditions and feeding strategies on the reactor cycle balances, including NO and N2O emissions were studied in detail. This study showed for the first time that total nitrogen removal rates of 0.5 g N?L?1?day?1 can be maintained when decreasing the temperature from 29 to 15 °C and when low nitrogen concentration and moderate COD levels are treated. Nitrite accumulation together with elevated NO and N2O emissions (5 % of N load) were needed to favor anammox compared with nitratation at low free ammonia (<0.25 mg N?L?1), low free nitrous acid (<0.9 μg N?L?1), and higher DO levels (3–4 mg O2?L?1). Although the total nitrogen removal rates showed potential, the accumulation of nitrite and nitrate resulted in lower nitrogen removal efficiencies (around 40 %), which should be improved in the future. Moreover, a balance should be found in the future between the increased NO and N2O emissions and a decreased energy consumption to justify OLAND mainstream treatment. 相似文献
5.
β-Glucosidase from Thermus thermophilus has specific hydrolytic activity for the outer glucose at the C-20 position in protopanaxadiol-type ginsenosides without hydrolysis of the inner glucose. The hydrolytic activity of the enzyme for gypenoside XVII was optimal at pH 6.5 and 90 °C, with a half-life of 1 h with 3 g enzyme l?1 and 4 g gypenoside XVII l?1. Under the optimized conditions, the enzyme converted the substrate gypenoside XVII to ginsenoside F2 with a molar yield of 100 % and a productivity of 4 g l?1 h?1. The conversion yield and productivity of ginsenoside F2 are the highest reported thus far among enzymatic transformations. 相似文献
6.
Javier Orduña-Rojas Luis Daniel García-Rodríguez Melina López-Meyer Rafael Riosmena-Rodríguez 《Journal of applied phycology》2013,25(6):1855-1861
Photosynthetic and respiratory responses (P–E curves) of Gracilaria parvispora from the southeast Gulf of California were studied at four temperatures (20, 25, 30, 35 °C) and salinity (25, 30, 35, 40 psu) combinations. The alga showed acclimation in its photosynthetic and respiratory responses to tropical temperature as well as to oceanic salinity. A positive effect of temperature on photosynthetic rate (P max) was observed for all salinities. Photosynthetic rates for treatments at 20 and 25 °C were lower (<9.2 mg O2?g dry weight (dw)?1?h?1) than for treatments at 30 and 35 °C (>12 mg O2 g dw?1?h?1). G. parvispora showed limited tolerance to low salinities (25 psu) and low temperatures (20 °C) and the interaction between temperature and salinity was significant (analysis of variance, P?<?0.05). Responses to salinity indicated adaptation to oceanic salinity. Photosynthetic responses were lower at 25 psu than at higher salinities. The lowest P max values (6.2–8.2 mg O2?g dw?1?h?1) were observed at the lowest salinity (25 psu) regardless of temperature. Compensation and saturation irradiances (26–170 and 57–149 μmol photons m?2?s?1, respectively) indicate adaptation to lower irradiances in shallow (1–2 m depth) habitats, where turbidity can be high, and the capacity of shade adaptation has been developed. Results suggest distribution of this species is mainly related to salinity or temperature. The potential mariculture efforts of G. parvispora would be limited by low temperatures in winter, and indicate that this species will probably not be able to spread further due to low temperatures (<15 °C) in the upper part of the Gulf of California. 相似文献
7.
Silicon deficiency is a lipid-promoting stress for many oleaginous diatoms. Literature reports suggest that reduced salinity in seawater, a primary component of which is sodium chloride, may inhibit metabolism of silicon in marine diatoms. We hypothesized that lowering sodium chloride below ocean levels may thus be effective in creating silicon stress and enhancing lipid productivity. We examined the interacting effects of silicon supply (0.05, 0.1, 0.2, and 0.8 mM) and sodium chloride concentration (50, 100, and 400 mM) on growth and lipid production in Chaetoceros gracilis. This was done in batch culture to facilitate the application of severe stress. Low levels of either sodium chloride or silicon resulted in at least 50 % increases in lipid content. The synergy of simultaneous, moderate sodium chloride and silicon stress resulted in lipid content up to 73 % of dry mass and lipid productivity of 1.7 g m?2 day?1; with a daily integrated photosynthetic photon flux of 17.3 mol photons m?2 day?1, the efficiency of lipid synthesis was thus 0.1 g mol?1 of photons. Decreased silicon also resulted in a 5 % shift in lipid chain length from C18 to C16 fatty acids. We observed a strong sodium chloride/silicon interaction on total and ash-free dry mass densities that arose because low sodium chloride concentrations were inhibitory to growth, but the inhibition was overcome with excessive silicon supply. This observation suggests that low levels of sodium chloride may have affected metabolism of silicon. The findings of this study can be used to enhance lipid production in oleaginous marine diatoms. 相似文献
8.
Global warming is associated with the continued increase in the atmospheric concentrations of greenhouse gases; carbon dioxide, methane (CH4) and nitrous oxide. Wetlands constitute the largest single natural source of atmospheric CH4 in the world contributing between 100 and 231 Tg year?1 to the total budget of 503–610 Tg year?1, approximately 60 % of which is emitted from tropical wetlands. We conducted diffusive CH4 emission measurements using static chambers in river channels, floodplains and lagoons in permanent and seasonal swamps in the Okavango Delta, Botswana. Diffusive CH4 emission rates varied between 0.24 and 293 mg CH4 m?2 h?1, with a mean (±SE) emission of 23.2 ± 2.2 mg CH4 m?2 h?1 or 558 ± 53 mg CH4 m?2 day?1. These emission rates lie within the range reported for other tropical wetlands. The emission rates were significantly higher (P < 0.007) in permanent than in seasonal swamps. River channels exhibited the highest average fluxes at 31.3 ± 5.4 mg CH4 m?2 h?1 than in floodplains (20.4 ± 2.5 mg CH4 m?2 h?1) and lagoons (16.9 ± 2.6 mg CH4 m?2 h?1). Diffusive CH4 emissions in the Delta were probably regulated by temperature since emissions were highest (20–300 mg CH4 m?2 h?1) and lowest (0.2–3.0 mg m?2 h?1) during the warmer-rainy and cooler winter seasons, respectively. Surface water temperatures between December 2010 and January 2012 varied from 15.3 °C in winter to 33 °C in summer. Assuming mean inundation of 9,000 km2, the Delta’s annual diffusive emission was estimated at 1.8 ± 0.2 Tg, accounting for 2.8 ± 0.3 % of the total CH4 emission from global tropical wetlands. 相似文献
9.
Yan Yao Ping Zhang Hui Liu Zhanyuan Lu Guijun Yan 《Plant Cell, Tissue and Organ Culture》2017,128(3):655-661
A bottleneck for genetic research and breeding of crop plants is the time taken to producing large pure line segregating populations so called recombinant inbred lines (RILs). One way to overcome this problem is through use of the single-seed-decent (SSD) process under in vitro conditions. A number of factors that may affect in vitro SSD approach of wheat including temperature, light duration and intensity, salt strength and carbohydrate concentration were investigated in this study. Under the in vitro conditions, 45 days per generation was achieved for an early flowering wheat genotype Emu Rock, allowing eight generations per annum; 58 days per generation was achieved for mid flowering genotypes, allowing six generations per annum. The results showed that a variation of growth environment before and after three-leaf stage allowed in vitro seed-set with a relatively short generation time. Specifically, the plantlets were first grown under 22?°C with a light intensity of 145 μmol m?2 s ?1 (16 h d?1) for 20 days (around three-leaf stage), and then moved to an environment of 28?°C and 500 μmol m?2 s?1 (20 h d?1) light. The culture medium was 1/2 strength Murashige and Skoog (MS) with modification of adding ten times of extra KH2PO4 and 4% sucrose. The fully in vitro protocol resulted in 100% flowering rate and average seed set rate of 91.5% in Emu Rock and Zippy. It can be further fine-tuned to suit different genotypes and it has a potential for factory scale mass-production of RILs for genetic studies and practical breeding programs. 相似文献
10.
The persistent edaphic stress on microbial succession due to dynamic changes during composting was explored for selection of multi-stress tolerant microbe(s) desirable for ethanol production. A total of 23 strains were isolated from mango compost using four successive enrichments in YP broth (g l?1): glucose, 100; 150; 250 with ethanol (40) and cycloheximide (0.4) at 40 °C, pH 6.0. Based on multi-gene ribotyping, 14 yeasts (61 %) of Saccharomycetaceae, 2 filamentous fungi (8.6 %) and 7 bacteria (30.4 %) were obtained. Phenetic and phylogenetic analysis of the 14 yeasts revealed 64.3 % tolerant to 500 g l?1 glucose, growth at 45 °C and resemblance to Candida sp. (14.3 %), Kluyveromyces marxianus (35.7 %), Pichia kudriavzevii (21.4 %) and Saccharomyces cerevisiae (28.6 %). Assessment of the 14 yeasts in glucose fermentation medium (pH 4.5 at 40 °C) showed ethanol productivity of ≥92 % by 12 yeasts with theoretical yields of 90–97 %. Fermentation of molasses (150 g l?1 glucose equivalent) by P. kudriavzevii D1C at 40 °C resulted in 73.70 ± 0.02 g l?1 ethanol and productivity of 4.91 ± 0.01 g l?1 h?1. Assessment of P. kudriavzevii D1C revealed multi-stress tolerance towards 5-hydroxymethyl furfural, ethanol (20 %, v/v), high gravity and H2O2 (0.3 M) indicating suitability for ethanol production using high gravity molasses and pre-treated lignocellulosic biomass fermentation. 相似文献
11.
A new strain of cyanobacteria was isolated from seawater samples collected near Jimo hot springs, Qingdao, China, and was identified as Cyanobacterium aponinum by 16S rDNA analysis. This study examined the effects of temperature, pH, light quality and high CO2 concentration on the growth of the cyanobacteria. Results showed that the strain exhibited a higher growth rate (about 168.4 mg L?1 day?1) at 35 °C than other temperatures (surviving at up to 50 °C) and a wide growth tolerance to acidic stress (pH 3.0 to 4.0) resulting from either H2SO4 or HNO3. The four light qualities, ranked by greatest to least biomass effect, were as follows: LED white light (LW) > LED red light (LR) > fluorescent white light (FW) > LED blue light (LB), achieving a higher lighting effect at a LW light intensity (60 μmol photons m?2 s?1) lower than other light qualities, which implied less energy consumption therewith. This strain demonstrates excellent CO2 tolerance at least 10% CO2 with the highest productivity in biomass (about 337.8 mg L?1 day?1) measured at 1% CO2 level. Results indicate that this strain is a promising candidate for use in biofixation of CO2 from flue gases emitted by thermoelectric plants. 相似文献
12.
Ashira Chanderman Adarsh Kumar Puri Kugen Permaul Suren Singh 《Bioprocess and biosystems engineering》2016,39(10):1577-1587
Optimization of process parameters for phytase production by Enterobacter sp. ACSS led to a 4.6-fold improvement in submerged fermentation, which was enhanced further in fed-batch fermentation. The purified 62 kDa monomeric phytase was optimally active at pH 2.5 and 60 °C and retained activity over a wide range of temperature (40–80 °C) and pH (2.0–6.0) with a half-life of 11.3 min at 80 °C. The kinetic parameters K m, V max, K cat, and K cat/K m of the pure phytase were 0.21 mM, 131.58 nmol mg?1 s?1, 1.64 × 103 s?1, and 7.81 × 106 M?1 s?1, respectively. The enzyme was fairly stable in the presence of pepsin under physiological conditions. It was stimulated by Ca+2, Mg+2 and Mn+2, but inhibited by Zn+2, Cu+2, Fe+2, Pb+2, Ba+2 and surfactants. The enzyme can be applied in dephytinizing animal feeds, and the baking industry. 相似文献
13.
Tobermolite effects on methane removal activity and microbial community of a lab-scale soil biocover
Kyung-Eun Moon Eun-Hee Lee Tae Gwan Kim Kyung-Suk Cho 《Journal of industrial microbiology & biotechnology》2014,41(7):1119-1129
Three identical lab-scale biocovers were packed with an engineered soil (BC 1), tobermolite only (BC 2), and a mixture of the soil and tobermolite (BC 3), and were operated at an inlet load of 338–400 g-CH4 m?2 d?1 and a space velocity of 0.12 h?1. The methane removal capacity was 293 ± 47 g-CH4 m?2 d?1 in steady state in the BC 3, which was significantly higher than those in the BC 1 and BC 2 (106 ± 24 and 114 ± 48 g-CH4 m?2 d?1, respectively). Quantitative PCR indicated that bacterial and methanotrophic densities (6.62–6.78 × 107 16S rDNA gene copy number g-dry sample?1 and 1.37–2.23 × 107 pmoA gene copy number g-dry sample?1 in the BC 1 and BC 3, respectively) were significantly higher than those in the BC 2. Ribosomal tag pyrosequencing showed that methanotrophs comprised approximately 60 % of the bacterial community in the BC 2 and BC 3, while they only comprised 43 % in the BC 1. The engineered soil favored the growth of total bacteria including methanotrophs, while the presence of tobermolite enhanced the relative abundance of methanotrophs, resulting in an improved habitat for methanotrophs as well as greater methane mitigation performance in the mixture. Moreover, a batch experiment indicated that the soil and tobermolite mixture could display a stable methane oxidation level over wide temperature (20–40 °C, at least 38 μmol g-dry sample?1 h?1) and pH (5–8, at least 61 μmol g-dry sample?1 h?1) ranges. In conclusion, the soil and tobermolite mixture is promising for methane mitigation. 相似文献
14.
Myall Lakes has experienced algal blooms in recent years which threaten water quality. Biomarkers, benthic fluxes measured with chambers, and pore water metabolites were used to identify the nature and reactivity of organic matter (OM) in the sediments of Bombah Broadwater (BB), and the processes controlling sediment-nutrient release into the overlying waters. The OM in the sediments was principally from algal sources although terrestrial OM was found near the Myall River. Terrestrial faecal matter was identified in muddy sediments and was probably sourced via runoff from farm lands. The reactive OM which released nutrients into the overlying waters was from diatoms, dinoflagellates and probably cyanobacteria. Microcystis filaments were observed in surface sediments. OM degradation rates varied between 5.3 and 47.1 mmol m?2 day?1 (64–565 mg m?2 day?1), were highest in the muddy sediments and sulphate reduction rates accounted for 20–40% of the OM degraded. Diatoms, being heavy sink rapidly, and are an important vector to transport catchment N and P to sites of denitrification and P-trapping in the sediments. Denitrification rates (mean ~4 mmol N m?2 day?1), up to 7 mmol N m?2 day?1 (105 mg N m?2 day?1) were measured, and denitrification efficiencies were highest (mean = 86 ± 4%) in the sandy sediments (~20% of the area of BB), but lower in the muddy sediments (mean = 63 ± 15%). These differences probably result from higher OM loads and anaerobic respiration in muddy sediments. Most DIP (>70%) from OM degradation was not released into overlying waters but remained trapped in surface sediments. Biophysical (advective) processes were responsible for the measured metabolite (O2, CO2, DSi, DIN and DIP) fluxes across the sediment–water interface. 相似文献
15.
L-asparaginase gene from Bacillus subtilis strain R5 (Asn-R5), comprising 990 nucleotides corresponding to a polypeptide of 329 amino acids, was cloned and expressed in Escherichia coli. Recombinant Asn-R5 was produced in soluble and active form exhibiting a specific activity of 223 μmol min?1 mg?1. The optimal temperature and pH for L-asparaginase activity of Asn-R5 were 35 °C and 9.0, respectively. Asn-R5 displayed a 50% activity with D-asparagine and 2% with L-glutamine compared to 100% with L-asparagine. No activity could be detected when D-glutamine was used as substrate. Half-life of the enzyme was 180 min at 35 °C and 40 min at 50 °C. There was no effect of metal ions and EDTA on the activity indicating that Asn-R5 enzyme activity is not metal ion dependent. The Km and Vmax values were 2.4 mM and 265 μmol min?1 mg?1, respectively. Activation energy for reaction catalyzed by Asn-R5 was 28 kJ mol?1. High L-asparaginase activity and thermostability of recombinant Asn-R5 may be beneficial for industrial production and application. 相似文献
16.
Ning Guo Jia Zheng Jian Tian Lishuang Wu Hongbo Zhou 《World journal of microbiology & biotechnology》2013,29(11):2095-2103
A putative endo-1,4-β-d-xylanohydrolase gene xyl11 from Aspergillus niger, encoding a 188-residue xylanase of glycosyl hydrolase family 11, was constitutively expressed in Pichia pastoris. The recombinant Xyl11 exhibited optimal activity at pH 5.0 and 50 °C, and displayed more than 68 % of the maximum activity over the temperature range 35–65 °C and 33 % over the pH range 2.2–7.0. It maintained more than 40 % of the original activity after incubation at 90 °C (pH 5.0) for 10 min and more than 75 % of the original activity after incubation at pH 2.2–11.0 (room temperature) for 2 h. The specific activity, K m and V max of purified Xyl11 were 22,253 U mg?1, 6.57 mg ml?1 and 51,546.4 μmol min?1 mg?1. It could degrade xylan to a series of xylooligosaccharides and no xylose was detected. The recombinant enzyme with high stability and catalytic efficiency could work over wide ranges of pH and temperature and thus has the potential for various industrial applications. 相似文献
17.
Mi-Hee Woo Young-Hyo Chang Hoi-Seon Lee Pyo June Pak Joong-Su Kim Namhyun Chung 《The protein journal》2014,33(1):110-117
A novel gene encoding thermostable endoglucanase was identified in Xanthomonas sp. EC102 from soil. The gene had 1,458 base pairs of open reading frame, which encode a 52-kDa protein of 486 amino acid residues. Sequence of the amino acid residues was similar with the endoglucanase from Xanthomonas campestris pv. campestris ATCC33913 (GenBank Accession No. NP_638867.1) (94 % identity). The endoglucanase was overexpressed in Escherichia coli BL21 and purified. Temperature for the highest enzymatic activity was 70 °C and pH optima was pH 5.5. The specific activity of the endoglucanase toward carboxymethylcellulose (CMC) was approximately 2 μmol min?1 mg?1, V max for CMC was 1.44 μmol mg?1 min?1, and K m values was 25.6 mg mL?1. The EC102 endoglucanase was stable at temperatures up to 60 °C, and it was activated by 0.1 mM of Mn2+ and Co2+. This is the first report about thermostable endoglucanase from Xanthomonas sp. 相似文献
18.
A putative endo-1,4-β-d-xylanohydrolase gene xyl10 from Aspergillus niger, encoding a 308-residue mature xylanase belonging to glycosyl hydrolase family 10, was constitutively expressed in Pichia pastoris. The recombinant Xyl10 exhibited optimal activity at pH 5.0 and 60 °C with more than 50 % of the maximum activity from 40 to 70 °C. It retained more than 90 % of the original activity after incubation at 60 °C (pH 5.0) for 30 min and more than 74 % after incubation at pH 3.0–13.0 for 2 h (25 °C). The specific activity, K m and V max values for purified Xyl10 were, respectively, 3.2 × 103 U mg?1, 3.6 mg ml?1 and 5.4 × 103 μmol min?1 mg?1 towards beechwood xylan. The enzyme degraded xylan to a series of xylooligosaccharides and xylose. The recombinant enzyme with these properties has the potential for various industrial applications. 相似文献
19.
Chou-Fei Wu Xiao-Ming Xu Qing Zhu Mao-Cheng Deng Lei Feng Juan Peng Jian-Ping Yuan Jiang-Hai Wang 《Applied microbiology and biotechnology》2014,98(8):3801-3807
The biodetoxification of cyanide-rich wastewater has become increasingly popular because of its cost-effectiveness and environmental friendliness. Therefore, we have developed an effective method, optimised by response surface methodology, for detoxifying cyanide-rich wastewater using Bacillus sp. CN-22, which was newly isolated from a cyanide-contaminated electroplating sludge and could tolerate a CN? concentration of 700 mg L?1. The concentration of CN? in the treated wastewater decreased from 200 to 6.62 mg L?1 after cultivation with 2.38 % inocula for 72 h on the medium, consisting of 0.05 % KH2PO4, 0.15 % K2HPO4, 1.0 mM MgCl2, 1.0 mM FeCl3, 0.1 % NH4Cl, and 0.1 % glycerol. The CN? degradability of 96.69 % is similar to the predicted value of 96.82 %. The optimal cultivation conditions were controlled as follows: initial pH, 10.3; temperature, 31 °C; and rotary speed, 193 rpm. The maintenance of higher pH in the overall treatment procedures may avoid the production of volatile HCN and the risk associated with cyanide detoxification. Additionally, the bacterial strain Bacillus sp. CN-22, with its potent cyanide-degrading activity at the initial CN– concentration of 200 mg L?1, may be employed to effectively treat cyanide-rich wastewater, especially electroplating effluent. 相似文献
20.
Shuang Li Jilin Xu Jiao Chen Juanjuan Chen Chengxu Zhou Xiaojun Yan 《Journal of applied phycology》2014,26(3):1389-1398
Diatoms are considered to have great potential as new biofuel sources because they can effectively accumulate triacylglycerols (TAGs). Detailed structure information of TAG in diatoms is much needed not only for the assessment of biofuel quality such as fatty acid chain length and unsaturation degree but also for the tracing of biosynthetic precursors because the biosynthesis of TAG is typically completed by utilizing the diacylglycerol acyltransferase in the cytoplasm. In this report, a comprehensive characterization of TAGs in marine diatoms was performed using ultra performance liquid chromatography–electrospray ionization–quadrupole time-of-flight mass spectrometry. Many types of major TAGs were identified for the first time in these diatoms: 12 TAGs in Chaetoceros debilis, 9 TAGs in Phaeodactylum tricornutum Bohlin, 16 TAGs in Nitzschia closterium f. minutissima, 16 TAGs in Thalassiosira weissflogii, 13 TAGs in Thalassiosira sp., 16 TAGs in Stephanodiscus asteaea and 7 TAGs in Skeletonema costatum. Semi-quantification of TAGs in these diatoms was also carried out, and it was found that the contents of individual TAGs ranged from 0.5?±?0.1 to 217.9?±?8.1 nmol mg?1 total lipids. In addition, the total lipid contents in diatoms ranged from 143.6?±?16.3 to 201.1?±?16.3 mg g?1 dry microalgae and the total TAG contents ranged from 36.8?±?9.5 to 793.2?±?54.4 nmol mg?1 total lipids. By comparative analysis of the compositions and concentrations of major TAGs in the seven algal strains, N. closterium f. minutissima with high abundance of TAGs containing the most monounsaturated fatty acids (mainly palmitoleic acid) was considered as one of the most promising diatom strains for microalgal biofuel production. Additionally, based on the information of sn-2 fatty acid obtained (mainly C16 in the sn-2 position), we propose the hypothesis that TAGs in diatoms are mainly derived from lipids in chloroplasts through the prokaryotic biosynthesis pathway, including monogalactosyldiacylglycerol and digalactosyldiacylglycerol. 相似文献