Photogeneration of Reactive Species from Biochar-Derived Dissolved Black Carbon for the Degradation of Amine and Phenolic Pollutants.

Due to agricultural waste combustion and large-scale biochar application, biochar-derived dissolved black carbon (DBC) is largely released into surface waters. The photogeneration of reactive species (RS) from DBC plays an important role in organic pollutant degradation. However, the mechanistic interactions between RS and pollutants are poorly understood. Here, we investigated the formation of DBC triplet states (3DBC*), singlet oxygen (1O2), and hydroxyl radical (•OH) in straw biochar-derived DBC solutions and photodegradation of typical pharmaceuticals and personal care products (PPCPs). Laser flash photolysis and electron spin resonance spectrometry showed that DBC exhibited higher RS quantum yields than some well-studied dissolved organic matter. The RS caused rapid degradation of atenolol, diphenhydramine, and propylparaben, selected as target PPCPs in this study. The 3DBC* contributed primarily to the oxidation of selected PPCPs via one-electron-transfer interaction, with average reaction rate constants of 1.15 × 109, 1.41 × 109, and 0.51 × 109 M-1 s-1, respectively. •OH also participated in the degradation and accounted for approximately 2.7, 2.5, and 18.0% of the total removal of atenolol, diphenhydramine, and propylparaben, respectively. Moreover, the photodegradation products were identified using high-resolution mass spectrometry, which further confirmed the electron transfer and •OH oxidation mechanisms. These findings suggest that DBC from the combustion process of agricultural biomass can efficiently induce the photodegradation of organic pollutants under sunlight in aquatic environments.

Biological and chemical phosphorus fractionalization in swine manure under aeration.

In this work, the dynamic responses of different phosphorous factions in swine manure to aeration treatment were investigated and profiled to provide insight on potential ways to improve the biological phosphorus removal process. Batch reactors fabricated from clear acrylic columns were filled with fresh swine manure containing a 4.6 % solids content, which was aerated continuously for 15 days at an airflow rate of 2 L/min. The results indicate that the treatment can reduce soluble phosphorus (P) by about 78 % after only one-day aeration due largely to chemical precipitations. At the end of the experiment, the average soluble inorganic P level was reduced by 12 % (from 91 down to 79 %), while the average soluble organic P was increased by 13 % (from 9 to 22 %). The biomass P (DNA/RNA/poly-P) was increased by 24 % in the first three days, but only by 14 % in the rest 12 days of aeration. Also increased by aeration was the lipid P (47 %) but not the protein P. The data reveal that the current aeration rate cannot maintain a stable oxygen level [represented by the oxidation-reduction potential (ORP)] in the treated manure, evidenced by the decrease in ORP from 250 mV at the beginning to almost zero at the conclusion of the experiment, which is considered the major factor hindering the growth of aerobes, including the phosphorus-accumulating organisms (PAOs). Therefore, it may be concluded that continuous aeration of swine manure at a constant rate will not guarantee the supply of sufficient oxygen to the growth of PAOs. On another front, it was observed that too much aeration might negatively impact the overall P removal by increasing the release of soluble organic P from dead cells.

First proof of concept of sustainable metabolite production from high solids fermentation of lignocellulosic biomass using a bacterial co-culture and cycling flush system.

To improve the lignocellulose conversion for ABE in high solids fermentation, this study explored the feasibility of cycling the process through the cellulolytic or/and solventogenic phases via intermittent flushing of the fermentation media. Five different flushing strategies (varying medium ingredients, inoculum supplement and cycling through phases) were investigated. Flushing regularly throughout the cellulolytic phase is necessary because re-incubation at 65 °C significantly improved glucose availability by at least 6-fold. The solvents accumulation was increased by 4-fold using corn stover (3-fold using miscanthus) over that produced by flushing only through the solventogenic phase. In addition, cycling process was simplified by re-incubating the flushed cellulolytic phase with no re-inoculation because the initial inoculum of Clostridiumthermocellum remained viable throughout sequential co-culture. This study served as the first proof of the cycling flush system applied in co-cultural SSC and the knowledge gained can be used to design a farm-scale flushing system.

One-step purification of glutamate decarboxylase from E. coli using aqueous two-phase system.

The aqueous two-phase system (ATPS), formed when two polymers or one polymer and one salt are mixed together at appropriate concentrations, is a clean technique to separate and purify biomolecules. ATPS has many advantages over traditional downstream process, especially on the integration of concentration, extraction, and partial purification if properly optimized, which reduce multiple processing steps involved hence in improving the yields and costs of the recovery process. Here, we describe an integrated purification process of glutamate decarboxylase (GAD) from E. coli cell extract using the established ATPS that consists of polyethylene glycol (PEG) and sodium sulfate.

Fungal secretomes enhance sugar beet pulp hydrolysis.

The recalcitrance of lignocellulose makes enzymatic hydrolysis of plant biomass for the production of second generation biofuels a major challenge. This work investigates an efficient and economic approach for the enzymatic hydrolysis of sugar beet pulp (SBP), which is a difficult to degrade, hemicellulose-rich by-product of the table sugar industry. Three fungal strains were grown on different substrates and the production of various extracellular hydrolytic and oxidative enzymes involved in pectin, hemicellulose, and cellulose breakdown were monitored. In a second step, the ability of the culture supernatants to hydrolyze thermally pretreated SBP was tested in batch experiments. The supernatant of Sclerotium rolfsii, a soil-borne facultative plant pathogen, was found to have the highest hydrolytic activity on SBP and was selected for further hydrolyzation experiments. A low enzyme load of 0.2 mg g(-1) protein from the culture supernatant was sufficient to hydrolyze a large fraction of the pectin and hemicelluloses present in SBP. The addition of Trichoderma reesei cellulase (1-17.5 mg g(-1) SBP) resulted in almost complete hydrolyzation of cellulose. It was found that the combination of pectinolytic, hemicellulolytic, and cellulolytic activities works synergistically on the complex SBP composite, and a combination of these hydrolytic enzymes is required to achieve a high degree of enzymatic SBP hydrolysis with a low enzyme load.

In vitro enzymatic conversion of γ-aminobutyric acid immobilization of glutamate decarboxylase with bacterial cellulose membrane (BCM) and non-linear model establishment.

The work investigated the properties and feasibility of using bacterial cellulose membrane (BCM) as a new and environmental friendly support carrier to immobilize glutamate decarboxylase (GAD) (a unique enzyme in the conversion of γ-aminobutyric acid (GABA) production). During cultivation, the porosities of BCM decreased successively with more extended fibrils piling above one another in a criss-crossing manner thus forming condensed and spatial structure. The BCM with this ultrafine network structure was found to immobilize GAD best via covalent binding because of the highest efficiency of immobilization (87.56% of the enzyme was bonded) and a good operational stability. And the covalent binding efficiency (amount of enzyme immobilized versus lost) was closely related to the porosity or the inner network of the BCM, not to the surface area. The capacity per surface area (mg/cm(2)) increased from 1.267mg/cm(2) to 3.683mg/cm(2) when the porosity of BCM ranged from 49% to 73.80%, while a declining trend of the loss of GAD specific activity (from 29.30%/cm(2) to 7.38%/cm(2)) was observed when the porosity increased from 49.9% to 72.30%. Two non-linear regression relationships, between the porosity and loading capacity and between porosity and enzyme activity loss, were empirically modeled with the determination of coefficient R(2) of 0.980 and 0.977, respectively. Finally, the established in vitro enzymatic conversion process demonstrated 6.03g/L of GABA at 0.10mol/L Glu, 60min of retention time and 160mL of suspension volume after the 1st run and a loss of 4.15% after the 4th run. The productivity of GABA was 6.03gL(-1)h(-1), higher than that from other reported processes.

System establishment of ATPS for one-step purification of glutamate decarboxylase from E. coli after cell disruption.

The partition of glutamate decarboxylase (GAD) from Escherichia coli in polyethylene glycol (PEG) and sodium sulfate aqueous two-phase systems (ATPS) has been explored with the purpose of establishing a phase system for the purification of GAD after cell disruption. The results showed that the partitioning of GAD was slightly influenced by PEG molecular weight (MW) but depended on the tie line length (TLL) and NaCl and loading sample concentrations. The optimum system obtained for GAD purification was composed of a PEG MW of 4,000, TLL of 63.5%, a volume ratio of 2.31, a loading sample concentration of 0.4 g/mL, which produced a GAD recovery of 90% with the purification fold of 73. Furthermore, the feasibility of directly purifying GAD from the cell disrupts using ATPS was evaluated. The established ATPS for GAD purification exhibited an efficient integrated purification process compared to the reported purification process in terms of purification efficiency and recovery.

Biogas and CH(4) productivity by co-digesting swine manure with three crop residues as an external carbon source.

Co-digesting swine manure with three agricultural residues, i.e., corn stalks, oat straw, and wheat straw, to enhance biogas productivity was investigated in this study. A 3x3 experimental design with duplicates was adopted (3 crop residuesx3 carbon/nitrogen ratios) to examine the improvement of batch digestion in terms of biogas volume produced, CH(4) content in the biogas, and net CH(4) volume. The crop residues were first cut into small sections and then ground into fine particles smaller than 40 mesh size (0.422mm) before being added to digesters. All the digesters were run simultaneously under controlled temperature at 37+/-0.1 degrees C. The length of experiment was 25days. The results showed that all crop residues significantly increased biogas production and net CH(4) volume at all C/N ratios, among which corn stalks performed the best with increase in daily maximum biogas volume by 11.4-fold as compared to the control, followed by oat straw (8.45-fold) and wheat straw (6.12-fold) at the C/N ratio of 20/1, which was found to be the optimal C/N ratio for co-digestion in the present study. In addition, corn stalks achieved the highest CH(4) content in the biogas ( approximately 68%), which was about 11% higher than that of oat straw ( approximately 57%), whereas wheat straw and the control both had produced biogas with approximately 47% CH(4) content. Wheat straw demonstrated a lower biogas productivity than corn stalks and oat straw even it had a higher carbon content (46%) than the latter two residues (39%).

Utilization of protein extract from dairy manure as a nitrogen source by Rhizopus oryzae NRRL-395 for l-lactic acid production.

Six levels of crude protein (0.21, 0.42, 0.84, 1.68, 2.52, and 3.36g/L) and six levels of protein hydrolysates from dairy manure, defined by degree of hydrolysis (DH, 6.9%, 17.2%, 25.9%, 33.8%, 36.1%, and 36.7%), were investigated as the nitrogen source for production of l-lactic acid by Rhizopus oryzae NRRL-395 with respect to the influence of nitrogen source on l-lactic acid yield and the correlation with biomass yield and mycelia morphology. Increases in crude protein from 0.21 to 1.68g/L led to an increase in l-lactic acid concentration in the culture media from 6.48 to 57.7g/L. However, further increases beyond 1.68g/L did not present continuing increases in l-lactic acid yields. The highest biomass yield was obtained at a crude protein nitrogen concentration of 2.52g/L. Hydrolysates with high DH resulted in high yields of l-lactic acid and biomass. At a nitrogen level of 0.42g/L (hydrolysates) with DH ranging from 33.8% to 36.7%, the l-lactic acid yield of 0.53-0.56g/g of glucose was achieved, coupled with a 13-14% yield of fungal biomass.

Development and optimization of a culture medium for L-lactic acid production by Rhizopus oryzae using crude protein from dairy manure as a nitrogen source.

Experiments were conducted using the crude protein in fresh dairy manure as the nitrogen source in the culture media for Rhizopus oryzae to produce L-lactic acid. Two uniform design experiments were carried out with one for optimizing seed culture while the other for best percent L-lactic acid production. Multiple linear regression and ANOVA analyses were employed to determine the most significant media components. Data from the first uniform design U6 (6(2)x 3), in which the experimental factors involved included nitrogen concentration (crude protein), spore concentration, and treatment duration, showed that the levels of these components in the optimal condition for the seed culture medium were 2.1 g/L nitrogen, 16 hour culture time, and 10(5) spore concentration. The biomass weight in the seed medium developed in this study reached 1.32 g/L, which was 48.3% higher than that of the control. The combination of culture time and nitrogen concentration was found to be most significant in influencing the biomass yield. In the second uniform design experiment, flask culture with five factors (glucose, nitrogen from dairy manure, ZnSO4, KH2PO4, and MgSO4) at eight levels was examined using the uniform design table U8 (8(5)) with the content of L-lactic acid as the evaluating response Y. The results showed that ZnSO4 had the most influence on L-lactic acid yield, followed by nitrogen and KH2PO4. The optimum culture medium in terms of lactic acid production consisted of 240 g/L glucose, 1.26 g/L crude protein, 1.05 g/L KH2PO4, and 0.25 g/L MnSO4, which could achieve a yield of 59.57% (7.1% higher than the control).