Harvesting biohydrogen from cellobiose from sulfide or nitrite-containing wastewaters using Clostridium sp. R1

Harvesting biohydrogen from inhibiting wastewaters is of practical interest since the toxicity of compounds in a wastewater stream commonly prevents the bioenergy content being recovered. The isolated Clostridium sp. R1 is utilized to degrade cellobiose in sulfide or nitrite-containing medium for biohydrogen production. The strain can effectively degrade cellobiose free of severe inhibitory effects at up to 200 mg l⁻¹ sulfide or to 5 mg l⁻¹ nitrite, yielding hydrogen at >2.0 mol H₂ mol⁻¹ cellobiose. Principal metabolites of cellobiose fermentation are acetate and butyrate, with the concentration of the former increases with increasing sulfide and nitrite concentrations. The isolated strain can yield hydrogen from cellobiose in sulfide-laden wastewaters. However, the present of nitrite significantly limit the efficiency of the biohydrogen harvesting process.     

Bio-kinetic analysis on treatment of textile dye wastewater using anaerobic batch reactor

An anaerobic digestion technique was applied to textile dye wastewater aiming at the colour and COD removal. Pet bottles of 5 L capacity were used as reactor which contains methanogenic sludge of half a liter capacity which was used for the treatment of combined synthetic textile dye and starch wastewater at different mixing ratios of 20:80, 30:70, 40:60, 50:50 and 60:40 with initial COD concentrations as 3520, 3440, 3360, 3264 and 3144 mg L⁻¹, respectively. The reactor was maintained at room temperature (30 ± 3 °C) with initial pH of 7. The maximum COD and colour removal were 81.0% and 87.3% at an optimum mixing ratio of 30:70 of textile dye and starch wastewaters. Both Monod’s and Haldane’s models were adopted in this study. The kinetic constants of cell growth under Haldane’s model were satisfactory when compared to Monod’s model. The kinetic constants obtained by Haldane’s model were found to be in the range of μ_max = 0.037-0.146 h⁻¹, K_s = 651.04-1372.88 mg L⁻¹ and K_i = 5681.81-18727.59 mg L⁻¹.     

Time dependent degradation of mixture of structurally different azo and non azo dyes by using Galactomyces geotrichum MTCC 1360

Galactomyces geotrichum MTCC 1360, a yeast species showed 88% ADMI (American dye manufacturing institute) removal of mixture of structurally different dyes (Remazol red, Golden yellow HER, Rubine GFL, Scarlet RR, Methyl red, Brown 3 REL, Brilliant blue) (70 mg l⁻¹) within 24 h at 30 °C and pH 7.0 under shaking condition (120 rpm). Glucose (0.5%) as a carbon source was found to be more effective than other sources used. The medium with metal salt (CaCl₂, ZnSO₄, FeCl₃, MgCl₂, CuSO₄) (0.5 mM) showed less ADMI removal as compared to control, but did not inhibit complete decolorization. The presence of tyrosinase, NADH-DCIP reductase and induction in laccase activity during decolorization indicated their role in degradation. HPTLC (High performance thin layer chromatography) analysis revealed the removal of individual dyes at different time intervals from dye mixture, indicating preferential degradation of dyes. FTIR (Fourier transform infrared spectroscopy) and HPLC (High performance liquid chromatography) analysis of samples before and after decolorization confirmed the biotransformation of dye. The reduction of COD (Chemical oxygen demand) (69%), TOC (Total organic carbon) (43%), and phytotoxicity study indicated the conversion of complex dye molecules into simpler oxidizable products having less toxic nature.     

Dynamics of microbial community for X-3B wastewater decolorization coping with high-salt and metal ions conditions

In this study, decolorization of Reactive Brilliant Red X-3B wastewater by the biological process coping with high salinity and metal ions conditions was investigated, and 16S rDNA based fingerprint technique was used to investigate microbial population dynamics. Results of sequencing batch tests showed that the microbial community could keep efficient with high concentration of dye (1100 mg L⁻¹), salt (150 g L⁻¹ NaCl) and some metal ions such as Mg²⁺, Ca²⁺ (1–10 mmol L⁻¹) and Pb²⁺ (1 mmol L⁻¹). 16S rDNA-based molecular analysis techniques demonstrated that the microbial community shifted during the acclimatization process affected by salt or metal ions. Some stains similar to Bacillus, Sedimentibacter, Pseudomonas, Clostridiales, Streptomyces and some uncultured clones acted for the dynamic succession, supposed as potential decolorization bacteria. This study provided insights on the decolorization capability and the population dynamic shifts during decolorization process of azo dye wastewater coping with salt and metal ions.     

Influence of food colorant and initial COD concentration on the efficiencies of micro-aerobic sequencing batch reactor (micro-aerobic SBR) for casein recovery under non-sterile condition by Lactobacillus casei TISTR 1500

The acid biocoagulants produced from non-sterile lactic acid fermentation by Lactobacillus casei TISTR 1500 were used to settle colloidal protein, mainly casein, at the isoelectric point in dairy effluent prior to secondary treatment. High concentration of azo dye (Ponceau 4R) in the dairy wastewater and the stress of starvation decreased the efficiencies of the micro-aerobic SBR. Consequently, low casein recovery obtained and organic removal suffered a decline. The number of lactic acid bacteria (LAB) also declined from log 7.4 to log 5.30 in the system fed with 400 mg L⁻¹ of the dye containing wastewater. The recovery of the system, however, showed that 25,000 mg COD L⁻¹ influent with 200 mg L⁻¹ of the dye maintained the growth of LAB in the range of log 7.74–8.12, with lactic and acetic production (2597 and 197 mg L⁻¹) and 83% protein removal. The results in this study suggested that the inhibitory effects were compensated with high organic content feeding.     

Comparison of polysialic acid production in Escherichia coli K1 during batch cultivation and fed-batch cultivation applying two different control strategies

The polysialic acid (PSA) production in Escherichia coli (E. coli) K1 was studied using three different cultivation strategies. A batch cultivation, a fed-batch cultivation at a constant specific growth rate of 0.25 h⁻¹ and a fed-batch cultivation at a constant glucose concentration of 50 mg l⁻¹ was performed. PSA formation kinetics under different cultivation strategies were analyzed based on the Monod growth model and the Luedeking-Piret equation. The results revealed that PSA formation in E. coli K1 was completely growth associated, the highest specific PSA formation rate (0.0489 g g⁻¹ h⁻¹) was obtained in the batch cultivation. However, comparing biomass and PSA yields on the glucose consumed, both fed-batch cultivations provided higher yields than that of the batch cultivation and acetate formation was prevented. Moreover, PSA yield on glucose was also correlated to the specific growth rate of the cells. The optimal specific growth rate for PSA production was 0.32 h⁻¹ obtained in the fed-batch cultivation at a constant glucose concentration of 50 mg l⁻¹, with highest conversion efficiency of 43 mg g⁻¹.     

An in vitro propagation protocol of two submerged macrophytes for lake revegetation in east China

Thirty-six programs have been set up to revegetate the degraded lake wetlands in east China since 2002. Most projects however faced deficiency of submerged macrophyte propagules. To solve the problem, alternative seedling sources must be found besides traditional field collection. This paper deals with an in vitro propagation protocol for two popularly used submerged macrophytes, Myriophyllum spicatum L. and Potamogeton crispus L. Full strength Murashige and Skoog-based liquid media (MS) plus 3% sucrose in addition to 0–2.0 mg l⁻¹ 6-benzylaminopurine (BA) and 0–1.0 mg l⁻¹ indoleacetic acid (IAA) were tried for shoot regeneration. Meanwhile, full, half or quarter strength MS in addition to 0, 0.1 or 0.2 mg l⁻¹ naphthaleneacetic acid (NAA) were tested for root induction, respectively. Results indicated that both species had the ability of regeneration from stem fragments in MS without further regulators. However, the addition of 2.0 mg l⁻¹ BA with 0.2 or 1.0 mg l⁻¹ IAA in MS drastically stimulated the regeneration efficiency of M. spicatum, while the addition of 2.0 mg l⁻¹ BA with 0.2 or 0.5 mg l⁻¹ IAA in MS significantly stimulated that of P. crispus. For root induction, full strength MS in combination with 0.1or 0.2 mg l⁻¹ NAA was preferred by M. spicatum, and the same MS without or with 0.1 mg l⁻¹ NAA was preferred by P. crispus. Seedlings of each species produced from tissue culture room had a 100% survival rate on clay, sandy loam or their mixture (1:1) in an artificial pond, and phenotypic plasticity was exhibited when the nutrient levels varied among the three types of sediments. This acclimation of seedlings helped develop the shoot and root systems, which ensured seedling quality and facilitated the transplantation. Our study has established an effective protocol to produce high quality seedlings for lake revegetation programs at a larger scale. Since the two species we tested represent different regeneration performances in nature but shared similar in vitro propagation conditions, this study has indicated a potentially wide use of the common media for preparing seedlings of other submerged macrophytes.     

Anaerobic degradation of tetrachlorobisphenol-A in river sediment

This study investigated the anaerobic degradation of tetrachlorobisphenol-A (TCBPA) in sediment samples collected at three sites along the Erren River in southern Taiwan. TCBPA anaerobic degradation half-lives (t_1/2) in the sediment were 12.6, 16.9 and 21.7 d at concentrations of 50, 100, and 250 ??g g⁻¹, respectively. TCBPA (50 ??g g⁻¹) anaerobic degradation half-lives (t_1/2) in the sediment were 10.1, 11.8, 11.0, 11.6, 10.8, 9.1, 8.5, 18.2, 19.3, and 16.1 d by the addition of yeast extract (5 mg l⁻¹), cellulose (0.96 mg l⁻¹), sodium chloride (1%), brij 30 (130 mg l⁻¹), brij 35 (43 mg l⁻¹), rhamnolipid (55 ??M), surfactin (91 ??M), phthalic esters (2 mg l⁻¹), nonylphenol (2 mg l⁻¹), and heavy metals (2 mg l⁻¹), respectively. The degradation rate of TCBPA was enhanced by the addition of yeast extract, cellulose, sodium chloride, brij 30, brij 35, rhamnolipid, or surfactin. However, it was inhibited by the addition of phthalic esters, nonylphenol, or heavy metals. Also noted was the presence of dichlorobisphenol-A and bisphenol-A, two intermediate products resulting from the anaerobic degradation of TCBPA accumulated in the sediments.     

Biochemical degradation pathway of reactive blue 13 by Candida rugopelliculosa HXL-2

A strain HXL-2 from a lab-scale sequence batch reactor (SBR) was identified as Candida rugopelliculosa based on its physiological, biochemical characteristics, and 26S rDNA D1/D2 gene phylogenetic analysis. About 90% of the 50 mg/L Reactive blue 13(RB13) was degraded in 48 h after inoculation with strain HXL-2. The optimum efficiency of pH on decolorization was obtained at pH 5.The optimum efficiency temperature of C. rugopelliculosa HXL-2 decolorization RB13 was obtained at 28 °C. The color removal efficiency was obtained at 80.3% when the feed concentration reached 2000 mg/L. We first detected naphthalene-like compound is produced as degradation intermediate after the cleavage of RB13 azo bond, detected 1-chloro-3-aniline- 2,4,6-triazine. We proposed degradation pathway of Reactive blue 13 by Candida sp and proved RB13 degradation pathway by Candida sp. has some difference from RB13 degradation pathway by Pseudomonas sp.     

Isolation and characterization of a fungus able to degrade pyrethroids and 3-phenoxybenzaldehyde

Fungal strain HU, isolated from activated sludge and identified as a member of the genus Cladosporium based on morphology and sequencing of 28S rRNA, was shown to degrade 90% of fenvalerate, fenpropathrin, β-cypermethrin, deltamethrin, bifenthrin, and permethrin (100 mg L⁻¹) within 5 days. Fenvalerate was utilized as sole carbon and energy source and co-metabolized in the presence of sucrose. Degradation of fenvalerate occurred at pH 5-10 at 18-38 °C. The fungus first hydrolyzed the carboxylester linkage to produce α-hydroxy-3-phenoxy-benzeneacetonitrile and 3-phenoxybenzaldehyde, and subsequently degraded these two compounds with a q_max, K_s and K_i of 1.73 d⁻¹, 99.20 mg L⁻¹ and 449.75 mg L⁻¹, respectively. Degradation followed first-order kinetics. These results show that the fungal strain may possess potential to be used in bioremediation of pyrethroid-contaminated environments.     

Enhanced production and partial characterization of an extracellular polysaccharide from newly isolated Azotobacter sp. SSB81

A strain was selected by its highest extracellular polysaccharide (EPS) production ability compare to other isolates from the same rhizospheric soil. The selected strain was identified by 16S rDNA sequencing and designated as SSB81. Phylogenetic analysis of the gene sequence showed its close relatedness with Azotobacter vinelandii and Azotobacter salinestris. Maximum EPS (2.52 g l⁻¹) was recovered when the basal medium was supplemented with glucose (2.0%), riboflavin (1 mg l⁻¹) and casamino acid (0.2%). The EPS showed a stable viscosity level at acidic pH (3.0–6.5) and the pyrolysis temperature was found to be at 116.73 °C with an enthalpy (ΔH) of 1330.72 Jg⁻¹. MALDI TOF mass spectrometric result suggests that polymer contained Hex₅Pent₃ as oligomeric building subunit. SEM studies revealed that the polymer had a porous structure with small pore size distribution indicating the compactness of the polymer. This novel EPS may find possible application as a polymer for environmental bioremediation and biotechnological processes.     

Microbial treatment of high-strength perchlorate wastewater

To treat wastewater containing high concentrations of perchlorate, a perchlorate reducing-bacterial consortium was obtained by enrichment culture grown on high-strength perchlorate (1200 mg L⁻¹) feed medium, and was characterized in a sequence batch reactor (SBR) over a long-time operation. The consortium removed perchlorate in the SBR with high reduction rates (35-90 mg L⁻¹ h⁻¹) and stable removal efficiency over 200-day operations. The maximum specific perchlorate reduction rate (q_max), half saturation constant (K_s), and optimal pH range were 0.67 mg-perchlorate mg-dry cell weight⁻¹ h⁻¹, 193.8 mg-perchlorate L⁻¹, and pH 7-9, respectively. The perchlorate reduction yield was 0.48 mol-perchlorate mol-acetate⁻¹. A clone library prepared using the amplicons of cld gene encoding chlorate dismutase showed that the dominant (per)chlorate reducing bacteria in the consortium were Dechlorosoma sp. (53%), Ideonella sp. (28%), and Dechloromonas sp. (19%).     

Biodegradation of phenanthrene and pyrene by Ganoderma lucidum

Biodegradation of two polycyclic aromatic hydrocarbons (PAHs), phenanthrene and pyrene, by a white rot fungus, Ganoderma lucidum, in broth cultures was investigated. It was found that the biomass of the organism decreased with the increase of PAH concentration in the cultures. In the cultures with 2 to 50 mg l⁻¹ PAHs, the degradation rate constants (k₁) increased with the PAH concentration, whereas, at the level of 100 mg l⁻¹, the degradation rate constants decreased. In the presence of 20 mg l⁻¹ PAHs, the highest degradation rates of both PAHs occurred in cultures with an initial pH of 4.0 at 30 °C. The addition of CuSO₄, citric acid, gallic acid, tartaric acid, veratryl alcohol, guaiacol, 2,2′-azino-bis-(3- ethylbenzothazoline-6-sulfonate) (ABTS) enhanced the degradation of both PAHs and laccase activities; whereas the supplement of oxalate, di-n-butyl phthalate (DBP), and nonylphenol (NP) decreased the degradation of both PAHs and inhibited laccase production. In conclusion, G. lucidum is a promising white rot fungus to degrade PAHs such as phenanthrene and pyrene in the environment.     

Enhanced 2,3-butanediol production by Klebsiella oxytoca using a two-stage agitation speed control strategy

Batch fermentative production of 2,3-butanediol by Klebsiella oxytoca was investigated using various oxygen supply methods though varying agitation speed. Based on the analysis of three kinetic parameters including specific cell growth rate (μ), specific glucose consumption rate (q_s) and specific 2,3-butanediol formation rate (q_p), a two-stage agitation speed control strategy, aimed at achieving high concentration, high yield and high productivity of 2,3-butanediol, was proposed. At the first 15 h, agitation speed was controlled at 300 rpm to obtain high μ for cell growth, subsequently agitation speed was controlled at 200 rpm to maintain high q_p for high 2,3-butanediol accumulation. Finally, the maximum concentration of 2,3-butanediol reached 95.5 g l⁻¹ with the yield of 0.478 g g⁻¹ and the productivity of 1.71 g l⁻¹ h⁻¹, which were 6.23%, 6.22% and 22.14% over the best results controlled by constant agitation speeds.     

Purification and characterization of two extracellular endochitinases from Massilia timonae

Two extracellular chitinases (designated as Chi-56 and Chi-64) produced by Massilia timonae were purified by ion-exchange chromatography, ammonium sulfate precipitation, and gel-filtration chromatography. The molecular mass of Chi-56 was 56 kDa as determined by both SDS-PAGE and gel-filtration chromatography. On the other hand, Chi-64 showed a molecular mass of 64 kDa by SDS-PAGE and 28 kDa by gel-filtration chromatography suggesting that its properties may be different from those of Chi-56. The optimum temperature, optimum pH, pI, K_m, and V_max of Chi-56 were 55 °C, pH 5.0, pH 8.5, 1.1 mg mL⁻¹, and 0.59 μmol μg⁻¹ h⁻¹, respectively. For Chi-64, these values were 60 °C, pH 5.0, pH 8.5, 1.3 mg mL⁻¹, and 1.36 μmol μg⁻¹ h⁻¹, respectively. Both enzymes were stimulated by Mn²⁺ and inhibited by Hg²⁺, and neither showed exochitinase activity. The N-terminal sequences of Chi-56 and Chi-64 were determined to be Q-T-P-T-Y-T-A-T-L and Q-A-D-F-P-A-P-A-E, respectively.     

Azo dye decolorization with a mutant Escherichia coli strain

A recombinant Escherichia coli strain (E. coli NO3) containing genomic DNA fragments from azo-reducing wild-type Pseudomonas luteola strain decolorized a reactive azo dye (C.I. Reactive Red 22) at approx. 17 mg dye h^–1 g cell. The ability to decolorize the azo dye probably did not originate from the plasmid DNA. Acclimation in azo-dye-containing media gave a nearly 10% increase in the decolorization rate of E. coli NO3. Growth with 1.25 g glucose l^–1 completely stopped the decolorization activity. When the decolorization metabolites from E. coli NO3 were analyzed by HPLC and MS, the results suggested that decolorization of the azo dye may be due to cleavage of the azo bond.     

Ecofriendly degradation of sulfonated diazo dye C.I. Reactive Green 19A using Micrococcus glutamicus NCIM-2168

Micrococcus glutamicus NCIM-2168 exhibited complete decolorization and degradation of C.I. Reactive Green 19A (an initial concentration of 50 mg l⁻¹) within 42 h at temperature 37 °C and pH 8, under static condition. Extent of mineralization was determined with total organic carbon (TOC) and chemical oxygen demand (COD) measurement, showing a satisfactory reduction of TOC (72%) and COD (66%) within 42 h. Enzyme studies shows involvement of oxidoreductive enzymes in decolorization/degradation process. Analytical studies of the extracted metabolites confirmed the significant degradation of Reactive Green 19A into various metabolites. The microbial toxicity and phytotoxicity assay revealed that the degradation of Reactive Green 19A produced nontoxic metabolites. In addition, the M. glutamicus strain was applied to decolorize a mixture of ten reactive dyes showing a 63% decolorization (in terms of decrease in ADMI value) within 72 h, along with 48% and 42% reduction in TOC and COD under static condition.     

Decolorization kinetics of a recombinant Escherichia coli strain harboring azo-dye-decolorizing determinants from Rhodococcus sp.

A 6.3 kb DNA fragment containing genes responsible for azo-dye decolorization was cloned and expressed in Escherichia coli. The resulting recombinant strain E. coli CY1 decolorized 200 mg azo dye (C.I. Reactive Red 22) l^–1 at 28 °C at 8.2 mg g cell^–1 h^–1, while the host (E. coli DH5) had no color-removal activity. Addition of 0.5 mM isopropyl--d-thiogalacto-pyranoside (IPTG) increased the decolorization rate 3.4-fold. The dependence of the decolorization rate on initial dye concentration essentially followed Monod-type kinetics and the maximal rate occurred with the dye at 600 mg l^–1. The decolorization rate of E. coli CY1 was optimal at 40 °C and pH 11. Aeration (increased dissolved O₂ level) strongly inhibited the decolorization, but decolorization occurred effectively under static incubation conditions (no agitation was employed). The CY1 strain also exhibited excellent stability during repeated-batch operations.     

Ecology of aquatic Ranunculus communities under the Mediterranean climate

The Iberian Peninsula encompasses more than 80% of the species richness of European aquatic ranunculi. The floristic diversity of the phytocoenosis characterised by aquatic Ranunculus and the main physical–chemical factors of the water were studied in 43 localities of the central Iberian Peninsula. Four aquatic Ranunculus communities are found in most of the aquatic environments. These are species-poor and have an uneven distribution: three species of Batrachium are heterophyllous and their communities are distributed in different aquatic ecosystems on silicated substrates; one species is homophyllous and its community occurs in various aquatic ecosystems with carbonated waters. In the Mediterranean climate, Ranunculus species are present in different habitats, as shown by the results of all the statistical analyses. Ranunculus trichophyllus communities occur in base-rich waters with a high buffering capacity (2273.44 ± 794.57 mg CaCO₃ L⁻¹) and a high concentration of cations (Ca²⁺, 121 ± 33.12 mg L⁻¹; Mg²⁺, 71.64 ± 82.77 mg L⁻¹), nitrates (2.89 ± 4.80 mg L⁻¹), ammonium (2.19 ± 1.36 mg L⁻¹) and sulphates (216.25 ± 218.54 mg L⁻¹). Ranunculus penicillatus communities are found in flowing waters with a high concentration of phosphates (0.48 ± 0.6 mg L⁻¹) and intermediate buffering capacity (683.66 ± 446.76 mg CaCO₃ L⁻¹). Both Ranunculus pseudofluitans and Ranunculus peltatus communities grow in waters with low buffering capacity (R. pseudofluitans, 385.91 ± 209.2 mg CaCO₃ L⁻¹; R. peltatus, 263.3 ± 180.36 mg CaCO₃ L⁻¹), and a low concentration of cations (R. pseudofluitans: Ca²⁺, 12.57 ± 9.42 mg L⁻¹; Mg²⁺, 3.42 ± 1.67 mg L⁻¹; R. peltatus: Ca²⁺, 15 ± 18.26 mg L⁻¹; Mg²⁺, 6.26 ± 8.89 mg L⁻¹) and nutrients (R. pseudofluitans: nitrates, 0.23 ± 0.2 mg L⁻¹; phosphates, 0.09 ± 0.1 mg L⁻¹; R. peltatus: nitrates, 0.19 ± 0.21 mg L⁻¹; phosphates, 0.09 ± 0.12 mg L⁻¹); the first in flowing waters, the latter in still waters.     

Biodecolorization of textile azo dyes by isolated yeast from activated sludge: Issatchenkia orientalis JKS6

An ascomycetous yeast strain isolated from activated sludge could decolorize Reactive Black 5 azo dye at 200 mg l^?1 up to 90 % within 12–18 h under agitated condition. Yeast decolorization ability was investigated at different RB5 concentrations and, at higher dye concentration, 500 mg l^?1, the decolorization was found to be 98 % after 36 h incubation time. Extensive decolorization (95–99 %) was obtained in presence of five other azo dyes, Reactive Orange 16, Reactive Red 198, Direct Blue 71, Direct Yellow 12, and Direct Black 22, by isolated yeast. HPLC analysis, UV–vis spectra and colorless biomass obtained after complete decolorization showed that the decolorization occured through a biodegradation mechanism. Decolorization was occurred during the exponential growth phase which is associated to primary metabolism. Laccase production by the yeast cells was not detected. The isolated yeast was characterized according to phenotypical and molecular procedures and was closely related (99 % identity) to Issatchenkia orientalis.