The growth of oleaginous Rhodotorula glutinis in an internal-loop airlift bioreactor by using mixture substrates of rice straw hydrolysate and crude glycerol

The conversion of lignocellulosic biomass (LCB) to microbial oils is attracting a growing amount of attention. However, the growth of the oleaginous yeast Rhodotorula glutinis on LCB hydrolysate (mainly rice straw) only will lead to a low lipid mass fraction, in the range of 10–20%. This study shows that the addition of crude glycerol to the LCB hydrolysate medium can efficiently raise the lipid mass fraction to the range of 30–40%. Crude glycerol is a by-product in the biodiesel production process. The use of renewable LCB hydrolysate and crude glycerol would greatly reduce the substrate cost for microbial oil production using R. glutinis. In addition, the results of experiments show that a low-cost airlift bioreactor is a more suitable fermentation process for the growth of R. glutinis than the use of a conventional agitation tank. When using mixed carbon sources of LCB hydrolysate with 30 kg m⁻³ of reducing sugars and 30 kg m⁻³ of crude glycerol, a maximal cell mass of 21.4 kg m⁻³ and lipid mass fraction of 58.5 ± 6.2 were achieved in an internal loop airlift bioreactor, and this process may have the potential to be applied in scale-up production.     

FP膨胀增强剂作用机理分析

通过差热分析，扫描电镜和孔径试验的方法，探讨了ＦＰ在砼中早强、增强、抗裂、抗渗的机理，并进行了分析．     

Borates in hydrolysis of ammonia borane

Ammonia borane NH₃BH₃ (19.5 wt% H) is able to release hydrogen by hydrolysis in the presence of a catalyst in ambient conditions. This reaction has received considerable attention since 2006, with special focus on the catalytic material. In comparison, important aspects like the nature of the hydrolysis by-product(s) have been much less investigated while a good identification of the borate(s) is required for approaching recyclability. In this context, we present a work based on a systematic approach that aims at characterizing the hydrolysate, its stability in time, and the borate(s) recovered after drying. It is shown that the hydrolysate consists in aqueous B(OH)₃ and that the solution (catalyst-free) is stable when stored 6 months under argon atmosphere at 30 °C. The extraction of the water from the hydrolysate was performed at different conditions (vacuum, or air; from −50 to 500 °C). It is observed that the higher the temperature, the lower the hydration degree of the borates. The total dehydration, with the formation of B₂O₃, can be obtained at heating at 500 °C. The main problem with the hydrolysate is the release of NH₃ during the drying stage. A solution is to remove NH₃ after hydrolysis and to dry the NH₃-free hydrolysate. By this way, H₃B₃O₆ forms. Hence, B₂O₃ and H₃B₃O₆ could be recovered and recycled into ammonia borane. Besides the identification of the borates, the suitability of ammonia borane for hydrogen production by hydrolysis is discussed, especially in comparison with sodium borohydride NaBH₄.     

Angiotensin I-converting enzyme inhibitory and hypocholesterolemic activities: Effects of protein hydrolysates prepared from Achatina fulica snail foot muscle

The angiotensin I-converting enzyme (ACE) inhibitory activity and hypocholesterolemic effect of Achatina fulica snail foot muscle protein hydrolysates (SFMPH) and its hydrolysates were studied. The SFMPHs were prepared at a temperature of 121°C for 60 min. To obtain the enzymatic hydrolysates, the SFMPHs were further hydrolysed with three proteases (papain, trypsin, or alcalase). Among all the hydrolysates, alcalase hydrolysate showed the highest degree of hydrolysis and was dominated by a small molecular size fraction (189–686 Da). The SFMPH treated by alcalase was effective in disintegrating intact cholesterol micelles. Furthermore, alcalase hydrolysate with a hydrolysis time of 60 min showed a strong ACE inhibitory activity in vitro with an IC₅₀ of 0.024 mg/mL. Therefore, alcalase hydrolysate may be a promising ingredient for the use in functional foods.     

胶原水解产物的分离研究

本文介绍了分离蛋白质常用的方法步骤，概述了胶原蛋白水解产物分离研究的情况，介绍了本实验室对酶水解胶原蛋白混合物分离的研究结果。     

APPLICATION OF EXPERIMENTAL DESIGN METHOD FOR ETHANOL PRODUCTION BY FERMENTATION OF SUNFLOWER SEED HULL HYDROLYSATE USING PICHIA STIPITIS NRRL-124

The lignocellulosic hydrolysates provide a rich medium for fermentation of sugars into ethanol. The potential use of sunflower seed hull hemicellulose hydrolysate in ethanol fermentation was evaluated by using the Experimental Design method in this study. A 2² Box-Wilson experimental design was used to develop a statistical model. The effects of shaking rate (55–145 rpm) and initial pH (4.6–7.4) on the fermentation of hydrolysate with Pichia stipitis yeast were studied in shaking bath experiments at 30°C. Model equations that represent maximum ethanol concentration E_max and ethanol yield Y_P/S in terms of shaking rate and pH were developed by using the Design-Expert package program. From response surfaces, optimum variables were calculated numerically by the Design-Expert computer program. Such a procedure provided the optimum values of the parameters with respect to both Y_P/S and E_max as X₁ = 5.89 pH and X₂ = 114.6 rpm. The maximum ethanol concentration of 11.04 g/L and ethanol yield of 0.32 were obtained with these optimized parameters.     

Biotoxicity assessment and lignocellulosic structural changes of phosphoric acid pre-treated young coconut husk hydrolysate for biohydrogen production

Major sugar constituents in young coconut husk were found to be glucans (0.30 g/g husk), while xylans were 0.10 g/g husk. Pre-treatments were carried out using phosphoric acid with dried coconut husk powder under steam heating. The effect of phosphoric acid on coconut husk hydrolysis was observed using acid concentrations of 0%, 1%, 5% and 10% (v/v). Soluble sugar concentration in hydrolysate was increasing proportional to acid concentration, as the total recovered solid decreases. FTIR and XRD analysis showed that acid hydrolysis led to the disruption of internal chemical bonds, causing coconut husk structural sugars to be released into the hydrolysate. Highest soluble sugar concentration, 29.9 g/L with a total suspended solid of 75.1 g/L, was obtained when the coconut husk was pre-treated with 10% phosphoric acid, and can be utilised for biohydrogen fermentation. Biotoxicity testing of the hydrolysates shows that half-maximal inhibition concentration of phosphoric acid was around 4.41% for a 24-h incubation and 3.80% for a 96-h incubation.     

Potential use of antioxidative mungbean protein hydrolysate as an anticancer asiatic acid carrier

This study investigated the potential use of mungbean (Vigna radiata (L.) Wilczek) protein hydrolysate (MPH) prepared from tryptic hydrolysis as an antioxidative hydrolysate and as a carrier for anticancer asiatic acid (AA). The antioxidant capacity of MPH was 0.67 and 0.46 ??mol Trolox equivalent (TE)/mg protein, as measured by oxygen radical absorbance capacity-fluorescein (ORAC_FL) and Trolox equivalent antioxidant capacity (TEAC) assays, respectively. Freeze-drying in lactose excipient reduced the antioxidant capacity of MPH to 0.48 ??mol TE/mg protein in ORAC_FL assay (P < 0.05) but did not alter antioxidant capacity determined by TEAC assay (P ≥ 0.05). The genotoxicity of H₂O₂ (50 ??M, 30 min) on hepatoblastoma HepG2 could be alleviated after HepG2 cells had taken up MPH after H₂O₂ exposure (P < 0.05). Moreover, the inhibition concentration (IC₅₀) of AA in HepG2 was lowered from 58.5 ??g mL^− 1 of AA alone to 38.5 ??g mL^− 1 when AA was freeze-dried with MPH in lactose excipient (P < 0.05). This study suggested that the efficacy of anticancer pentacyclic triterpene AA against hepatoblastoma HepG2 could be increased by co-drying with antioxidative mungbean protein hydrolysate in lactose excipient.     

Purification and characterization of an antioxidative peptide from enzymatic hydrolysate of yellowfin sole (<Emphasis Type="Italic"> Limanda aspera</Emphasis>) frame protein

In order to utilize yellowfin sole ( Limanda aspera) frame protein (YFP), which is normally discarded as industrial waste in the process of fish manufacture, yellowfin sole frame protein hydrolysates (YFPHs) were fractionated using an ultrafiltration (UF) membrane system following hydrolysis with pepsin and mackerel intestines crude enzyme (MICE). The YFPHs were separated into five major types, YFPH-I (30–10 kDa), YFPH-II (10–5 kDa), YFPH-III (5–3 kDa), YFPH-IV (3–1 kDa), and YFPH-V (below 1 kDa) by using UF membranes with molecular weight cut-offs of 30, 10, 5, 3, and 1 kDa, respectively. The antioxidative activity of the YFPHs was investigated and compared with that of a natural antioxidant, -tocopherol, used as a reference. Furthermore, the fraction showing strong antioxidative activity was isolated from the YFPHs using consecutive chromatographic methods on an SP-Sephadex C-25 column, on a Sephadex G-75 column, and high-performance liquid chromatography (HPLC) on an octadecylsilane column. The molecular mass of the antioxidant was identified as 13 kDa using HPLC on a gel permeation chromatography (GPC) column, and the antioxidative peptide was composed of 10 N-terminal amino acid residues, RPDFDLEPPY.     

Detection of furfural and 5-hydroxymethylfurfural with a yhcN::luxCDABE bioreporter strain

RT-qPCR data demonstrated that the yhcN gene was highly expressed when Escherichia coli was exposed to 500 ppm of ferulic acid (9.8-fold), vanillin (7.3-fold) or furfural (2.2-fold). Consequently, an E. coli yhcN::lux bioreporter strain (DMY1) was constructed. This strain is very responsive to furfural and 5-hydroxymethylfurfural, showing a maximum induced bioluminescence of 29.4- and 17.8-fold, respectively. The responses to different phenolics were also significant, with relative responses of between 4- and 16-fold. In tests with rice straw hydrolysate samples, a dual induction of DMY1 was observed and it was demonstrated that this corresponded to the activities of the phenolics and HMF within the sample. The maximum response seen with the hydrolysate sample was 3.5 and the minimum phenolic concentration detected was 39 mg/L. These results illustrate that this strain can be used to monitor for the presence of furans and phenolics commonly found within plant hydrolysate samples.