Coating function and stabilizing effects of surface layer protein from Lactobacillus acidophilus ATCC 4356 on liposomes.

Surface layer proteins (SLPs) are crystalline arrays in the outermost layer of cell envelope in many archaea and bacteria. SLPs subunits have the ability to reassemble on the surface of lipid layers. In this work, the SLP from Lactobacillus acidophilus ATCC 4356 was extracted and reassembled on the surface of positively charged liposomes composed of dipalmitoyl phosphatidylcholine, cholesterol and octadecylamine. Zeta potentials and particle size were determined to describe the adsorption process of SLP on liposomes. The liposomes completely coated with SLP were observed by transmission electron microscope. To investigate the stabilizing effects of SLP on liposomes, carboxyfluorescein (CF) was encapsulated and its leakage was determined as an evaluation index. The results showed that the L. acidophilus ATCC 4356 SLP significantly (P < 0.05) increased the stability of the liposomes in the course of thermal challenge. Furthermore, SLP was able to reduce the aggregation of liposomes in serum. Storage stability of liposomes was performed at 25 °C, 4 °C and -20 °C for 90 days. And the SLP-coated liposomes released less CF than the control liposomes during storage at the three evaluated temperatures. Our findings extended the application field of Lactobacillus SLPs and introduced a novel nanocarrier system with good chemical stability.

Co-production of xylooligosaccharides and activated carbons from Camellia oleifera shell treated by the catalysis and activation of zinc chloride.

Camellia oleifera shell (COS) is a worthy byproduct in woody edible oil production enriched in hemicellulose and lignin. This paper aims to explore the high-value transformation of COS for the production of xylooligosaccharides (XOS) with main degree of polymerization (DP) of 2-5 by the catalysis of ZnCl2. The effect of pretreatment temperature, reaction time and ZnCl2 concentration on the contents and DP distributions of XOS were analyzed. Moderate reaction conditions tended to achieve high content XOS, and the maximum value 61.38% and 14.39 g/L of XOS yield and concentration, respectively, peaked at 170 °C for 30 min using 0.5% (w/w) ZnCl2. The first time the solid residues derived from the production process of XOS were used as the precursor for the co-production of activated carbons (AC). The maximum iodine values and BET surface area were 5623.94 mg/g and 1244.46 m2/g, respectively, using 2.20 M ZnCl2 as the activating agent.

Effective lactic acid production from waste paper using Streptococcus thermophilus at low enzyme loading assisted by Gleditsia saponin.

Waste paper has considerable potential as a raw material for lactic acid (LA) production due to high cellulose content, abundance and low cost. In this study, four kinds of waste papers were used for LA production through simultaneous saccharification and fermentation (SSF) by Streptococcus thermophilus. The SSF of office paper achieved the highest LA concentration (39.71 g/L), while the highest LA yield was observed for magazine (99.56%), followed by office paper (82.85%). High LA concentration is unfavorable to total LA conversion because of product inhibition. However, the addition of Gleditsia saponin (GS) could obtain both high yield and high concentration of LA at a low enzyme loading, indicating that product inhibition could be moderated. A lactic acid yield of 86.30% was obtained from office paper at an enzyme loading of 9 FPU/g-cellulose with GS, which was higher than that of without GS at a higher loading of 18 FPU/g-cellulose.

Acetyl-assisted autohydrolysis of sugarcane bagasse for the production of xylo-oligosaccharides without additional chemicals.

The aim of this work was to study acetyl-assisted autohydrolysis of sugarcane bagasse for the production of xylo-oligosaccharides without additional chemicals. A xylo-oligosaccharide yield of 50.35% was obtained in 10 min through sugarcane bagasse autohydrolysis at 200 °C; this yield was 49.64% after acetyl-assisted autohydrolysis of a 65:35 mixture of sugarcane bagasse/white birch at 160 °C for 100 min. The yield of xylo-oligosaccharides was close to that obtained at 180 °C/40 min and 200 °C/10 min through the autohydrolysis of sugarcane bagasse. Compared to sugarcane bagasse alone, the xylo-oligosaccharide (degree of polymerization 2-5) yield from the acetyl-assisted autohydrolysis at 200 °C for 10 min was 52.99%. In addition, the yield of glucose from the solid residue following autohydrolysis pretreatment was 96.87% after 72 h of enzymatic hydrolysis. These results demonstrate that acetyl-assisted autohydrolysis is a promising method for the production of xylo-oligosaccharides.

Enhancement of ethanol production from green liquor-ethanol-pretreated sugarcane bagasse by glucose-xylose cofermentation at high solid loadings with mixed Saccharomyces cerevisiae strains.

BACKGROUND: Efficient cofermentation of glucose and xylose is necessary for economically feasible bioethanol production from lignocellulosic biomass. Here, we demonstrate pretreatment of sugarcane bagasse (SCB) with green liquor (GL) combined with ethanol (GL-Ethanol) by adding different GL amounts. The common Saccharomyces cerevisiae (CSC) and thermophilic S. cerevisiae (TSC) strains were used and different yeast cell mass ratios (CSC to TSC) were compared. The simultaneous saccharification and cofermentation (SSF/SSCF) process was performed by 5-20% (w/v) dry substrate (DS) solid loadings to determine optimal conditions for the co-consumption of glucose and xylose. RESULTS: Compared to previous studies that tested fermentation of glucose using only the CSC, we obtained higher ethanol yield and concentration (92.80% and 23.22 g/L) with 1.5 mL GL/g-DS GL-Ethanol-pretreated SCB at 5% (w/v) solid loading and a CSC-to-TSC yeast cell mass ratio of 1:2 (w/w). Using 10% (w/v) solid loading under the same conditions, the ethanol concentration increased to 42.53 g/L but the ethanol yield decreased to 84.99%. In addition, an increase in the solid loading up to a certain point led to an increase in the ethanol concentration from 1.5 mL GL/g-DS-pretreated SCB. The highest ethanol concentration (68.24 g/L) was obtained with 15% (w/v) solid loading, using a CSC-to-TSC yeast cell mass ratio of 1:3 (w/w). CONCLUSIONS: GL-Ethanol pretreatment is a promising pretreatment method for improving both glucan and xylan conversion efficiencies of SCB. There was a competitive relationship between the two yeast strains, and the glucose and xylose utilization ability of the TSC was better than that of the CSC. Ethanol concentration was obviously increased at high solid loading, but the yield decreased as a result of an increase in the viscosity and inhibitor levels in the fermentation system. Finally, the SSCF of GL-Ethanol-pretreated SCB with mixed S. cerevisiae strains increased ethanol concentration and was an effective conversion process for ethanol production at high solid loading.

Comparative study of alkaline hydrogen peroxide and organosolv pretreatments of sugarcane bagasse to improve the overall sugar yield.

Green liquor (GL) combined with H2O2 (GL-H2O2) and green liquor (GL) combined with ethanol (GL-ethanol) were chosen for treating sugarcane bagasse. Results showed that the glucose yield (calculated from the glucose content as a percentage of the theoretical glucose available in the substrates)of sugarcane bagasse from GL-ethanol pretreatment (97.7%) was higher than that from GL-H2O2 pretreatment (41.7%) after 72h hydrolysis with 18 filter paper unit (FPU)/g-cellulose for cellulase, 27,175 cellobiase units (CBU)/g-cellulose for ß-glucosidase. Furthermore, about 94.1% of xylan was converted to xylose after GL-ethanol pretreatment without additional xylanase, while the xylose yield was only 29.2% after GL-H2O2 pretreatment. Scanning electron microscopy showed that GL-ethanol pretreatment could break up the fiber severely. Moreover, GL-ethanol pretreated substrate was more accessible to cellulase and more hydrophilic than that of GL-H2O2 pretreated. Therefore, GL-ethanol pretreatment is a promising method for improving the overall sugar (glucose and xylan) yield of sugarcane bagasse.