Co-production of microbial oil and exopolysaccharide by the oleaginous yeast Sporidiobolus pararoseus grown in fed-batch culture

The production cost of microbial oil was reduced by improving the exopolysaccharide (EPS) production to share the production cost using Sporidiobolus pararoseus JD-2. Batch fermentation demonstrated that S. pararoseus JD-2 has the potential to co-produce oil and EPS with 120 g L⁻¹ glucose, 20 g L⁻¹ corn steep liquor and 10 g L⁻¹ yeast extract as carbon and nitrogen sources. Using fed-batch fermentation for 72 h resulted in oil and EPS production of 41.6 ± 2.5 g L⁻¹ and 13.1 ± 0.6 g L⁻¹ with the productivity of 0.58 g L⁻¹ h⁻¹ and 0.182 g L⁻¹ h⁻¹, respectively. The fat soluble nutrients in the oil were studied, indicating that it was constituted of 79.19% unsaturated fatty acids and contained 505 mg per kg-oil of carotenoids. Moreover, the EPS contained only one type of polysaccharide; the main monosaccharide compositions were galactose, glucose and mannose in a proportion of 16 : 8 : 1. These results implied that EPS produced by S. pararoseus JD-2 was a new type of EPS.

The production cost of microbial oil was reduced by improving the exopolysaccharide (EPS) production to share the production cost using Sporidiobolus pararoseus JD-2.     

Nutrient value of fish manure waste on lactic acid fermentation by Lactobacillus pentosus

The aim of this work was to study the feasibility of using fish manure waste as a nutrient source for lactic acid fermentation. Fish waste contains nitrogen and minerals that could support the growth of lactic acid bacteria (LAB), making it a good candidate as the nutrient source for lactic acid fermentation. Two different fish manure wastes, from Nile tilapia and channel catfish aquaculture, were investigated for their performance on different sugar substrates. Both fish waste types showed low efficiency in the direct fermentation of glucose, but satisfactory efficiencies in simultaneous saccharification and fermentation (SSF) of cellulosic materials, such as pure cellulose and paper sludge. The highest lactic acid yield obtained was 87% and 91%, with a corresponding volumetric productivity of 1.006 and 0.580 g L⁻¹ h⁻¹, and corresponding lactic acid concentration of 96 and 56 g L⁻¹ for cellulose and paper sludge, respectively. Fish waste concentrations did not show much impact on lactic acid production for the SSF process, where increasing fish waste from 10 to 30 g L⁻¹ resulted in less than a 10% yield increase. In the present study, fish manure waste was shown to be an effective and economic nutrient source for lactic acid production by SSF.

Fish manure wastes are an effective nutrient source for lactic acid production using simultaneous saccharification and fermentation.     

Co-production of solvents and organic acids in butanol fermentation by Clostridium acetobutylicum in the presence of lignin-derived phenolics

Co-production of solvents (butanol, acetone, and ethanol) and organic acids (butyrate and acetate) by Clostridium acetobutylicum using lignocellulosic biomass as a substrate could further enlarge the application scope of butanol fermentation. This is mainly because solvents and organic acids could be used for production of fine chemicals such as butyl butyrate, butyl oleate, etc. However, many phenolic fermentation inhibitors are formed during the pretreatment process because of lignin degradation. The present study investigated the effects of five typical lignin-derived phenolics on the biosynthesis of solvents and organic acids in C. acetobutylicum ATCC 824. Results obtained in 100 mL anaerobic bottles indicated that butanol concentration was enhanced from 10.29 g L⁻¹ to 11.36 g L⁻¹ by the addition of 0.1 g L⁻¹ vanillin. Subsequently, a pH-control strategy was proposed in a 5 L anaerobic fermenter to alleviate the “acid crash” phenomenon and improve butanol fermentation performance, simultaneously. Notably, organic acid concentration was enhanced from 6.38 g L⁻¹ (control) to a high level of 9.21–12.57 g L⁻¹ with vanillin or/and vanillic acid addition (0.2 g L⁻¹) under the pH-control strategy. Furthermore, the butyrate/butanol ratio reached the highest level of 0.80 g g⁻¹ with vanillin/vanillic acid co-addition, and solvent concentration reached 13.85 g L⁻¹, a comparable level to the control (13.69 g L⁻¹). The effectiveness and robustness of the strategy for solvent and organic acid co-production was also verified under five typical phenolic environments. In conclusion, these results suggest that the proposed process strategy would potentially promote butanol fermentative products from renewable biomass.

Lignin-derived phenolics enhance solvent and organic acid biosynthesis in butanol fermentation by Clostridium acetobutylicum ATCC 824.     

Improved conversion of bamboo shoot shells to furfuryl alcohol and furfurylamine by a sequential catalysis with sulfonated graphite and biocatalysts

Furfurylamine and furfuryl alcohol are known as important furfural-upgrading derivatives in the production of pharmaceuticals, fibers, additives, polymers, etc. In a one-pot manner, the catalysis of biomass into furan-based chemicals was established in a tandem reaction with sulfonated Sn–graphite catalysts and biocatalysts. Using a raw bamboo shoot shell (75.0 g L⁻¹) as the feedstock, a high furfural yield of 41.1% (based on xylan) was obtained using the heterogeneous Sn–graphite catalyst (3.6 wt% dosage) in water (pH 1.0) for 30 min at 180 °C. Under the optimum bioreaction conditions, the biomass-derived furfural could be transformed into furfuryl alcohol (0.310 g furfuryl alcohol per g xylan in biomass) by a reductase biocatalyst or furfurylamine (0.305 g furfurylamine per g xylan in biomass) using an ω-transaminase biocatalyst. Such one-pot chemoenzymatic processes combined the merits of both heterogeneous catalysts and biocatalysts, and sustainable processes were successfully constructed for synthesizing key bio-based furans.

Furfurylamine and furfuryl alcohol are known as important furfural-upgrading derivatives in the production of pharmaceuticals, fibers, additives, polymers, etc.     

Enhanced exopolysaccharide yield and antioxidant activities of Schizophyllum commune fermented products by the addition of Radix Puerariae

To increase the production of exopolysaccharides (EPS) and expand the application of Schizophyllum commune (S. commune) fermentation liquid, the traditional Chinese medicine Radix Puerariae (RP) with outstanding biological activity was selected as a culture additive to improve the EPS yield and enhance the antioxidant activity of fermented products from S. commune. The effects of three independent factors: A: initial pH (5.0–6.0), B: concentration of RP (10–14 g L⁻¹), and C: inoculum size (8–12%, v/v) on the EPS yield were evaluated. The results of response surface methodology (RSM) showed that the optimal fermentation conditions were: A: 5.40, B: 12.80 g L⁻¹, and C: 10.0%. The optimal yield of EPS was 8.41 ± 0.12 mg mL⁻¹, which showed an insignificant (p > 0.05) difference with the predicted value (8.45 mg mL⁻¹). The fermented supernatants cultured from RP-supplemented medium (SC-RP) or regular medium (SC) were collected for further study. FT-IR analysis of EPS-1 (purified from SC) and EPS-2 (purified from SC-RP) showed that their structures were consistent, indicating that the addition of RP did not affect the structure of schizophyllan (SPG). In addition, compared with SC, the in vitro antioxidant activities of SC-RP were significantly improved with ORAC values and FRAP values increasing by 11.56-fold and 14.69-fold, respectively. There was a significant correlation among the phenolic compounds, flavonoids, and antioxidant activity of SC-RP in this study. Besides, SC-RP was detected to contain more than 25 bioactive ingredients compared with that of SC, which may play a key role in its antioxidant activities. Thus, these results indicated that RP enhanced the yield of SPG and improved the antioxidant activity of the fermented products by S. commune. Accordingly, the fermentation liquid of S. commune with the addition of RP may have potential application in food, cosmetics, and pharmaceutical industries.

To increase the production of exopolysaccharides and expand the application of Schizophyllum commune fermentation liquid, the traditional Chinese medicine Radix Puerariae with outstanding biological activity was selected as a culture additive.     

Performance and mechanism of conductive magnetite particle-enhanced excess sludge anaerobic digestion for biogas recovery

The aim of this study was to evaluate the effect of magnetite particles on the anaerobic digestion of excess sludge. The results showed that methane production increased with the increase in magnetite dosage in the range of 0–5 g L⁻¹, and the cumulative methane production increased by 50.1% at a magnetite dosage of 5 g L⁻¹ compared with the blank reactor after 20 days. Simultaneously, numerous volatile fatty acids (VFAs) were produced at high magnetite dosages, providing the required substrates for methanogenesis. The concentration of magnetite addition was positively correlated with methane production, which proved that magnetite was beneficial for the promotion of the conversion of VFAs to methane. Moreover, the degradation efficiencies of proteins and carbohydrates reached 64% and 52.6% at the magnetite dosage of 5 g L⁻¹, respectively, and corresponding activities of protease and coenzyme F420 were 9.03 IU L⁻¹ and 1.652 μmol L⁻¹. In addition, the Methanosaeta and Methanoregula genus were enriched by magnetite, which often participate in direct interspecies electron transfer as electron acceptors.

Magnetite particles were applied to excess sludge anaerobic digestion. The methane production and sludge reduction were related to magnetite particle dosage, and the Methanosaeta and Methanoregula involved in the electron transfer were enriched.     

Open simultaneous saccharification and fermentation of l-lactic acid by complete utilization of sweet sorghum stalk: a water-saving process

A complete and efficient utilization of sweet sorghum stalk including sweet sorghum juice (SSJ) and sweet sorghum bagasse (SSB) was achieved via the open simultaneous saccharification and fermentation (SSF) of l-lactic acid. To simplify the pretreatment process and reduce water consumption, a combined hydrolysis approach was applied and the NaOH-pretreated liquor (SL) was utilized as a partial neutralizing agent. In order to further enhance the product titer, the acid hydrolysate of SSJ (SSJAH) was fed, and MgO was used as a neutralizing agent. A product titer of 94 g L⁻¹ was obtained with a productivity of 1.55 g L⁻¹ h⁻¹, and the yield reached 98.31%. Totally, 274.79 g l-lactic acid was produced from 1 kg sweet sorghum stalk, and 83.22% water was saved compared with the previous study based on alkali pretreatment of SSB. This study provides an effective process for l-lactic acid biosynthesis from lignocellulosic substrates.

Sweet sorghum stalk was completely used for l-lactic acid biosynthesis based on combined hydrolysis with saving 83.22% water.     

Developing a screen-printed graphite–polyurethane composite electrode modified with gold nanoparticles for the voltammetric determination of dopamine

A screen-printed electrode (SPGPUE) was prepared with graphite–polyurethane composite ink containing gold nanoparticles (AuNPs), resulting in a screen-printed graphite–polyurethane composite electrode modified with gold nanoparticles (SPGPUE–AuNPs). Gold nanoparticles were prepared by the citrate method and extracted from the water medium since polyurethane is not compatible with humidity. After extraction to chloroform, they were characterized via transmission electron microscopy (TEM). The presence of gold on the SPGPUE–AuNP surface was confirmed via SEM and EDX analyses, while thermogravimetry revealed the presence of approximately 3.0% (m/m) gold in the composite. An electrochemical pretreatment in 0.10 mol L⁻¹ phosphate buffer (pH 7.0) with successive cycling between −1.0 V and 1.0 V (vs. pseudo-Ag/AgCl) under a scan rate of 200 mV s⁻¹ and 150 cycles was required in order to provide a suitable electrochemical response for the voltammetric determination of dopamine. After the optimization of the parameters of differential pulse voltammetry (DPV), an analytical curve was obtained within a linear dynamic range of 0.40–60.0 μmol L⁻¹ and detection limit (LOD) of 1.55 ×10⁻⁸ mol L⁻¹ for dopamine at the SPGPUE–AuNP. A non-modified SPGPUE was used for comparison and a linear range was obtained between 2.0 and 10 μmol L⁻¹ with an LOD of 2.94 × 10⁻⁷ mol L⁻¹. During the dopamine determination in cerebrospinal synthetic fluid (CSF), recoveries between 89.3 and 103% were achieved. There were no significant interferences from ascorbic acid and uric acid, but some from epinephrine due to the structural similarity.

A screen-printed modified composite electrode (SPGPUE) was prepared with graphite–polyurethane ink containing gold nanoparticles (AuNPs), resulting in a sensor with improved sensitivity regarding the unmodified device in dopamine determination.     

Synthesis,biological activity and toxicity to zebrafish of benzamides substituted with pyrazole-linked 1,2,4-oxadiazole

To find pesticidal lead compounds with high activity, a series of novel benzamides substituted with pyrazole-linked 1,2,4-oxadiazole was designed and synthesized by using the splicing principle of active substructures. The chemical structures of the target compounds were confirmed by ¹H NMR, ¹³C NMR and HRMS. The preliminary bioassay showed that most compounds displayed good larvicidal activities against mosquito larvae at 10 mg L⁻¹. In particular, compound 12g exhibited obvious activity; its lethal rate reached up to 100% (at 5 mg L⁻¹) and 55% (at only 2 mg L⁻¹). Furthermore, compound 12f (70.6%) and 12h (100%) showed good fungicidal activities against Pyricularia oryzae, with EC₅₀ values of 8.28 and 5.49 μg mL⁻¹, respectively, which were superior to that of the control drug bixafen (9.15 μg mL⁻¹). Finally, the LC₅₀ of compound 12h to zebrafish embryo was 0.39 mg L⁻¹, so it was classified as a high-toxic compound. Thus, this compound may be used as a potential lead compound for further structural optimisation to develop new compounds with high activity and low toxicity.

A series of novel benzamides substituted with pyrazole-linked 1,2,4-oxadiazole was designed and synthesized by using the splicing principle of active substructures.     

Angelica gigas ameliorates the destruction of gingival tissues via inhibition of MMP-9 activity

Angelica gigas (AG) has been used for periodontal diseases in traditional Korean medicine. However, the effects of AG on periodontitis have not been clarified yet. In this study, we investigated the ameliorative effects of AG against ligature-induced periodontitis. Sprague-Dawley rats were divided into four groups; non-ligatured (normal), ligatured and treated with vehicle (ligatured), ligatured and treated with 1 mg mL⁻¹ AG (AG1), and ligatured and treated with 100 mg mL⁻¹ AG (AG100). 70% ethanol extracts of AG were topically applied onto both sides of the first molar daily for 14 days. In addition, human dermal fibroblast cells were treated with 1, 10 and 100 μg mL⁻¹ AG to characterize the expression of matrix metallopeptidase 9 (MMP-9). Topical AG treatment reduced alveolar bone resorption, as assessed by methylene blue staining. The structures of soft gingival tissues (periodontal pocket) were recovered in the AG-treated groups. The expression of MMP-9 was decreased, and that of type 1 collagen was significantly increased in AG-treated gingival tissues. In addition, AG treatment inhibited the activity of MMP-9 in LPS-treated human dermal fibroblast cells. This study reveals that topical AG treatment has the potential to ameliorate the destruction of gingival tissues by inhibiting MMP-9 activity. AG may be a candidate for the treatment of periodontitis.

Angelica gigas (AG) has been used for periodontal diseases in traditional Korean medicine.     

Enhancing the removal efficiency of methylene blue in water by fly ash via a modified adsorbent with alkaline thermal hydrolysis treatment

An effective adsorbent of methylene blue was synthesized from coal fly ash (FA; waste material from a coal power plant) by a denaturing process with an alkaline solution at 90 °C. The denatured fly ash (D-FA) has a surface area and pore volume of 66.39 m² g⁻¹ and 15.33 cm³ g⁻¹, respectively, whereas the values of the original FA are negligible, i.e., 3.55 m² g⁻¹ and 0.02 cm³ g⁻¹. The removal of methylene blue (MB) in aqueous solution by D-FA was increased in the range of initial MB concentration (10–20 mg L⁻¹); contact time (0–120 min); pH (2–8); D-FA dosage (1–4 g L⁻¹). However, a larger value of those operational parameters would not improve the removal activity. Furthermore, the methylene blue adsorption on the denatured FA was fitted with the Langmuir model with R² = 0.9991; the maximum adsorption capacity was determined as 28.65 mg g⁻¹ from the model. Overall, the highest removal efficiency of MB using D-FA with the dosage of 4 g L⁻¹ was 97.1% in 30 mg L⁻¹ solution of methylene blue at pH = 7. The alkaline hydrothermal denaturation of waste FA is a promising approach to produce an adsorbent with beneficial environmental engineering applications.

High efficiency of methylene blue adsorbent from waste coal fly ash by treatment with alkaline thermal hydrolysis.     

Performance of selenate removal by biochar embedded nano zero-valent iron and the biological toxicity to Escherichia coli

The application of nano zero-valent iron (nZVI) in water environment was limited by its easily aggregation and potential biological toxicity. In this study, biochar embedded nZVI (BC-nZVI) was prepared by carbon-thermal reduction method, and the SEM-EDX mapping results showed that nZVI was successfully embedded on biochar. Meanwhile, BC-nZVI with the optimal Fe/C of 2/1 showed a similar Se(vi) removal efficiency to pure nZVI. Effects of pH, BC-nZVI loading, and initial Se(vi) concentration were studied. Se(vi) removal rates (at 30 min) by BC-nZVI at pH 4.0 and 5.0 were 98.2% and 95.9%, respectively. But Se(vi) removal rate (at 30 min) was sharply decreased to 25.8% at pH 6.0. With the increase of BC-nZVI loading from 0.5 g L⁻¹ to 1 g L⁻¹, Se(vi) removal rate (at 30 min) significantly increased from 25.5% to 95.9%. And the continuous increase of BC-nZVI loading to 2 g L⁻¹ did not improve Se(vi) removal rate. Se(vi) less than 3 mg L⁻¹ was completely removed by BC-nZVI in 30 min, but Se(vi) more than 6 mg L⁻¹ only was removed about 25.9% at 30 min. Optimal parameters were pH 4.0, 2 g L⁻¹ BC-nZVI, and 1.5 mg L⁻¹ Se(vi). Variation of calculated amount, SOD activity, and protein content of Escherichia coli with nZVI and BC-nZVI indicated that nZVI and BC-nZVI both produced negative effects on the growth of E. coli. But the amount and SOD activity of E. coli with pure nZVI was lower than that with BC-nZVI. Moreover, E. coli with nZVI released more protein than that with BC-nZVI. So modified nZVI by biochar was less harmful to E. coli than nZVI.

The application of nano zero-valent iron (nZVI) in water environment was limited by its easily aggregation and potential biological toxicity.     

Interaction behaviors and structural characteristics of zein/NaTC nanoparticles

Bile salts are biosurfactants distributed in the human gastrointestinal tract, which can significantly influence the structure and functions of orally administrated components. This work has studied the interaction and conformation changes of zein with sodium taurocholate (NaTC) in the formation of zein/NaTC nanoparticles. When the NaTC concentration (C_NaTC) increases from 0 to 0.24 g L⁻¹, the particle size of zein/NaTC nanoparticles decreases from 97 to 76 nm, but markedly increases from 76 to 137 nm as C_NaTC increases from 0.24 to 0.4 g L⁻¹. At C_NaTC = 0–0.24 g L⁻¹, the sharply decreased zeta potential of zein/NaTC nanoparticles suggests that NaTC monomers electrostatically bind with zein molecules to form zein/NaTC complexes, which have high steric repulsion and thus aggregate into smaller zein/NaTC nanoparticles. Nevertheless, at C_NaTC = 0.24–0.4 g L⁻¹, the less changed zeta potential of zein/NaTC nanoparticles together with the surface tension result suggests that NaTC dimers formed on zein polypeptide chains due to the hydrophobic interaction cause zein/NaTC complexes to undergo more aggregation into larger zein/NaTC nanoparticles. Compared to little changes in the secondary and tertiary structures of zein molecules at C_NaTC = 0–0.24 g L⁻¹, the absorption, fluorescence, and circular dichroism measurements disclose that the addition of NaTC above 0.24 g L⁻¹ can greatly unfold the compact structure of zein molecules with decreased α-helix content.

Bile salts are biosurfactants distributed in the human gastrointestinal tract, which can significantly influence the structure and functions of orally administrated components.     

Correction: Ascorbic acid/Fe0 composites as an effective persulfate activator for improving the degradation of rhodamine B

Correction for ‘Ascorbic acid/Fe⁰ composites as an effective persulfate activator for improving the degradation of rhodamine B’ by Xiangyu Wang et al., RSC Adv., 2018, 8, 12791–12798.

The authors regret that the unit on the x-axis of Fig. 1 was incorrectly written as “% wt” rather than “‰ wt” in the original article. The correct version of Fig. 1 is presented below.Open in a separate windowFig. 1(a) Comparison of removal efficiency of RhB in different systems (C₀ = 50 mg L⁻¹, PS dosage = 1.4 g L⁻¹, Fe⁰ dosage = 1 g L⁻¹, H₂A/Fe⁰ dosage = 1 g L⁻¹, H₂A dosage = 1.6 g L⁻¹ and T = 298 K); (b) effect of H₂A concentration on removal efficiency of RhB in the H₂A/Fe⁰–PS system (C₀ = 50 mg L⁻¹, Fe⁰ dosage = 0.8 g L⁻¹, T = 298 K and the solution volume is 50 mL).The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Identification and in situ removal of an inhibitory intermediate to develop an efficient phytosterol bioconversion process using a cyclodextrin-resting cell system

A classically versatile steroid intermediate, 9α-hydroxyandrost-4-ene-3,17-dione (9α-OH-AD), can be obtained by phytosterol (PS) bioconversion using Mycobacterium. In this study, a cyclodextrin-resting cell reaction system with a high concentration of PS (50 g L⁻¹) was used to produce 9α-OH-AD. However, the inhibitory effect of metabolic intermediates is a key factor limiting production efficiency. After the separation and identification of a series of metabolic intermediates, it was found that 4-ene-3-keto steroids, which are the first metabolites of sterol side-chain degradation, accumulated at the beginning of the bioprocess and had a remarkable inhibitory effect on bioconversion. The bioconversion rate was greatly improved when 5 g L⁻¹ of macroporous adsorbent resin D101 was added to the reaction system in the initial phase. A certain amount of resin acted as a reservoir to remove the inhibitory intermediate in situ and facilitated the bioconversion process, and the 9α-OH-AD space–time yield increased to 8.51 g L⁻¹ d⁻¹, which was 23.15% higher than that without resin addition (6.91 g L⁻¹ d⁻¹) after 72 h bioconversion. In summary, we identified an inhibitory intermediate that limits the bioconversion rate and provided a solution based on resin adsorption for improving 9α-OH-AD production efficiency in a commercial-scale process.

We identified an inhibitory intermediate, 4-ene-3-keto steroids, that limits the bioconversion rate and provided a solution based on resin adsorption for improving 9α-OH-AD production efficiency in a commercial-scale process.     

Novel chalcone derivatives containing a 1,2,4-triazine moiety: design,synthesis, antibacterial and antiviral activities

A series of novel chalcone derivatives containing the 1,2,4-triazine moiety were synthesized and their structures were confirmed by ¹H NMR, ¹³C NMR and elemental analyses. Antiviral bioassays revealed that most of the compounds exhibited good antiviral activity against tobacco mosaic virus (TMV) at a concentration of 500 μg mL⁻¹. The designated compound 4l was 50% effective in terms of curative and protective activities against TMV with 50% effective concentrations (EC₅₀) of 10.9 and 79.4 μg mL⁻¹, which were better than those of ningnanmycin (81.4 and 82.2 μg mL⁻¹). Microscale thermophoresis (MST) also showed that the binding of compound 4l to coat protein (TMV-CP) yielded a K_d value of 0.275 ± 0.160 μmol L⁻¹, which was better than that of ningnanmycin (0.523 ± 0.250 μmol L⁻¹). At the same time, molecular docking studies for 4l with TMV-CP (PDB code:1EI7) showed that the compound was embedded well in the pocket between the two subunits of TMV-CP. Meanwhile, compound 4a demonstrated excellent antibacterial activities against Ralstonia solanacearum (R. solanacearum), with an EC₅₀ value of 0.1 μg mL⁻¹, which was better than that of thiodiazole-copper (36.1 μg mL⁻¹) and bismerthiazol (49.5 μg mL⁻¹). The compounds act by causing folding and deformation of the bacterial cell membrane as observed using scanning electron microscopy (SEM). The chalcone derivatives thus synthesized could become potential alternative templates for novel antiviral and antibacterial agents.

A series of novel chalcone derivatives containing the 1,2,4-triazine moiety were synthesized and their structures were confirmed by ¹H NMR, ¹³C NMR and elemental analyses.     

Synergistic and simultaneous biosorption of phenanthrene and iodine from aqueous solutions by soil indigenous bacterial biomass as a low-cost biosorbent

The removal of phenanthrene and iodine from aqueous solutions in single and binary systems by inactivated soil indigenous bacterial biomass (SIBB), as well as affecting factors, were evaluated. Sorption kinetic and isotherm studies were carried out to investigate the synergistic effects of phenanthrene and iodine. Optimal parameters for the biosorption process included a solution pH of 6.0 and biosorbent dosage of 0.75 g L⁻¹. The ionic strength significantly decreased the biosorption of both phenanthrene and iodine in single conditions, while no obvious influences were found in the binary conditions. A pseudo-second-order model was well fitted to the kinetic biosorption data for both phenanthrene and iodine. The results showed that the presence of co-solute accelerated the biosorption processes and the pseudo-second-order biosorption rates (k₂) for phenanthrene and iodine increased from 0.005441 to 0.009825 g mg⁻¹ min⁻¹ and from 0.000114 to 0.000223 g mg⁻¹ min⁻¹, respectively. The SIBB showed strong affinity with both phenanthrene and iodine, with a partition coefficient K_d (Linear model) of 6892.4 L kg⁻¹ for phenanthrene and affinity parameter K_L (Langmuir model) of 232 500 L kg⁻¹ for iodine. The presence of co-solute illustrated a synergistic effect on the biosorption of phenanthrene and iodine due to intermolecular forces between phenanthrene and iodine, enhancing the K_d of 34.7% for phenanthrene and K_L of 107.0% for iodine, respectively. The results suggested that SIBB was an effective material for the simultaneous biosorption of phenanthrene and iodine from aqueous solutions.

Co-solute significantly enhanced the sorption affinity of phenanthrene and iodine by bacterial biomass.     

Quantification and isotherm modelling of competitive phosphate and silicate adsorption onto micro-sized granular ferric hydroxide

Adsorption onto ferric hydroxide is a known method to reach very low residual phosphate concentrations. Silicate is omnipresent in surface and industrial waters and reduces the adsorption capacity of ferric hydroxides. The present article focusses on the influences of silicate concentration and contact time on the adsorption of phosphate to a micro-sized iron hydroxide adsorbent (μGFH) and fits adsorption data to multi-component adsorption isotherms. In Berlin drinking water (DOC of approx. 4 mg L⁻¹) at pH 7.0, loadings of 24 mg g⁻¹ P (with 3 mg L⁻¹ initial PO₄³⁻–P) and 17 mg L⁻¹ Si (with 9 mg L⁻¹ initial Si) were reached. In deionized water, phosphate shows a high percentage of reversible bonds to μGFH while silicate adsorption is not reversible probably due to polymerization. Depending on the initial silicate concentration, phosphate loadings are reduced by 27, 33 and 47% (for equilibrium concentrations of 1.5 mg L⁻¹) for 9, 14 and 22 mg L⁻¹ Si respectively. Out of eight tested multi-component adsorption models, the Extended Freundlich Model Isotherm (EFMI) describes the simultaneous adsorption of phosphate and silicate best. Thus, providing the means to predict and control phosphate removal. Longer contact times of the adsorbent with silicate prior to addition of phosphate reduce phosphate adsorption significantly. Compared to 7 days of contact with silicate (c₀ = 10 mg L⁻¹) prior to phosphate (c₀ = 3 mg L⁻¹) addition, 28 and 56 days reduce the μGFH capacity for phosphate by 21 and 43%, respectively.

Adsorption of phosphate onto ferric hydroxide in complex waters is influenced by effects of competition, displacement and surface blockage.     

Effect of lignocellulose-derived weak acids on butanol production by Clostridium acetobutylicum under different pH adjustment conditions

The effects of formic acid, acetic acid and levulinic acid on acetone–butanol–ethanol (ABE) fermentation under different pH adjustment conditions were investigated using Clostridium acetobutylicum as the fermentation strain. CaCO₃ supplementation can alleviate the inhibitory effect of formic acid on ABE production. The ABE titers from the medium containing 0.5 g L⁻¹ formic acid with pH adjusted by CaCO₃ and KOH were 11.08 g L⁻¹ and 1.04 g L⁻¹, which reached 64.8% and 6.3% of the control group, respectively. Compared with CaCO₃ pH adjustment, fermentation results with higher ABE titers and yields were obtained from the medium containing acetic acid or levulinic acid, when the pH was adjusted by KOH. When formic acid, acetic acid, and levulinic acid co-existed in the medium, better fermentation result was achieved by adjusting the pH by CaCO₃. Moreover, 12.50 g L⁻¹ ABE was obtained from the medium containing 2.0 g L⁻¹ acetic acid, 0.4 g L⁻¹ formic acid, and 1.0 g L⁻¹ levulinic acid as compared to 3.98 g L⁻¹ ABE obtained from the same medium when the pH was adjusted by KOH. CaCO₃ supplementation is a more favorable pH adjustment method for ABE medium preparation from lignocellulosic hydrolysate.

The effects of formic acid, acetic acid and levulinic acid on acetone–butanol–ethanol (ABE) fermentation under different pH adjustment conditions were investigated using Clostridium acetobutylicum as the fermentation strain.     

Synthesis and biological activities of novel trifluoromethylpyridine amide derivatives containing sulfur moieties

A series of trifluoromethylpyridine amide derivatives containing sulfur moieties (thioether, sulfone and sulfoxide) was designed and synthesized. Their antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo), Ralstonia solanacearum (R. solanacearum) and insecticidal activities against P. xylostella were evaluated. Notably, the half-maximal effective concentration (EC₅₀) value of sulfone-containing compound F10 is 83 mg L⁻¹ against Xoo, which is better than that of commercial thiodiazole copper (97 mg L⁻¹) and bismerthiazol (112 mg L⁻¹). Thioether-containing compounds E1, E3, E5, E6, E10, E11 and E13 showed much higher activities against R. solanacearum with the EC₅₀ value from 40 to 78 mg L⁻¹, which are much lower than that of thiodiazole copper (87 mg L⁻¹) and bismerthiazol (124 mg L⁻¹). Generally, most of the sulfone-containing compounds and sulfoxide-containing compounds showed higher activities against Xoo than that of the corresponding thioether-containing compound, but most of the thioether-containing compounds contributed higher antibacterial activities against R. solanacearum. Furthermore, title compounds E3, E11, E24 and G2 showed good insecticidal activities of 75%, 70%, 70% and 75%, respectively.

Novel trifluoromethylpyridine amide derivatives containing sulfur moieties were synthesized, which exhibited good antibacterial and insecticidal activities for potential crop protection agents.