Background： Bacterial cellulose (BC) is a nanostructured material with unique properties and wide applicability. In order to decrease the production cost of bacterial cellulose, lignocellulose-based media have considerable potential as alternative cost-effective feedstocks. However, pretreatment and enzymatic hydrolysis of lignocellulose to sugars also generate fermentation inhibitors. Detoxification of lignocellulosic hydrolysates is needed to achieve efficient production of BC. In this investigation, different methods for detoxification of spruce hydrolysate prior to production of BC were compared with respect to effects on potential inhibitors and fermentable sugars, sugar consumption, BC yield, and cell viability. The objectives were to identify efficient detoxification methods and to achieve a better understanding of the role played by different inhibitors in lignocellulosic hydrolysates. Results： In a first series of experiments, the detoxification methods investigated included treatments with activated charcoal, alkali [sodium hydroxide, calcium hydroxide (overliming), and ammonium hydroxide], anion and cation ion-exchange resins, and reducing agents (sodium sulfite and sodium dithionite). A second series of detoxification experiments included enzymatic treatments (laccase and peroxidase). The potential inhibitors studied included aliphatic acids, furan aldehydes, and phenolic compounds. The best effects in the first series of detoxification experiments were achieved with activated charcoal and anion exchanger. After detoxification with activated charcoal the BC yield was 8.2 g/L, while it was 7.5 g/L in a reference medium without inhibitors. Treatments with anion exchanger at pH 10 and pH 5.5 gave a BC yield of 7.9 g/L and 6.3 g/L, respectively. The first series of experiments suggested that there was a relationship between the BC yield and phenolic inhibitors. Therefore, the second series of detoxification experiments focused on treatments with phenol-oxidizing enzymes. The BC yield in the laccase-detoxified hydrolysate reached 5.0-5.5 g/L after 14 days cultivation, which demonstrated the important inhibitory role played by phenolic compounds. Conclusions： The investigation shows that detoxification methods that efficiently remove phenolics benefit bacterial growth and BC production. Negative effects of salts could not be excluded and the osmotolerance of Gluconacetobacter xylinus needs to be further investigated in the future. Combinations of detoxification methods that efficiently decrease the concentration of inhibitors remain as an interesting option. ___________________________________________________ http://www.microbialcellfactories.com/content/12/1/93 http://www.microbialcellfactories.com/content/pdf/1475-2859-12-93.pdf

BACKGROUND: Bacterial cellulose (BC) is a highly crystalline and mechanically stable nanopolymer, which has excellent potential as a material in many novel applications, especially if it can be produced in large amounts from an inexpensive feedstock. Waste fiber sludge, a residue with little or no value, originates from pulp mills and lignocellulosic biorefineries. A high cellulose and low lignin content contributes to making the fiber sludge suitable for bioconversion, even without a thermochemical pretreatment step. In this study, the possibility to combine production of BC and hydrolytic enzymes from fiber sludge was investigated. The BC was characterized using field-emission scanning electron microscopy and X-ray diffraction analysis, and its mechanical properties were investigated. RESULTS: Bacterial cellulose and enzymes were produced through sequential fermentations with the bacterium Gluconacetobacter xylinus and the filamentous fungus Trichoderma reesei. Fiber sludges from sulfate (SAFS) and sulfite (SIFS) processes were hydrolyzed enzymatically without prior thermochemical pretreatment and the resulting hydrolysates were used for BC production. The highest volumetric yields of BC from SAFS and SIFS were 11 and 10 g/L (DW), respectively. The BC yield on initial sugar in hydrolysate-based medium reached 0.3 g/g after seven days of cultivation. The tensile strength of wet BC from hydrolysate medium was about 0.04 MPa compared to about 0.03 MPa for BC from a glucose-based reference medium, while the crystallinity was slightly lower for BC from hydrolysate cultures. The spent hydrolysates were used for production of cellulase with T. reesei. The cellulase activity (CMCase activity) in spent SAFS and SIFS hydrolysates reached 5.2 U/mL (87 nkat/mL), which was similar to the activity level obtained in a reference medium containing equal amounts of reducing sugar. CONCLUSIONS: It was shown that waste fiber sludge is a suitable raw material for production of bacterial cellulose and enzymes through sequential fermentation. The concept studied offers efficient utilization of the various components in fiber sludge hydrolysates and affords a possibility to combine production of two high value-added products using residual streams from pulp mills and biorefineries. Cellulase produced in this manner could tentatively be used to hydrolyze fresh fiber sludge to obtain medium suitable for production of BC in the same biorefinery. http://www.biotechnologyforbiofuels.com/content/6/1/25 http://www.biotechnologyforbiofuels.com/content/pdf/1754-6834-6-25.pdf

An ionic liquid [AMIM]Cl was used to pretreat wheat straw with an aim to remarkably improve enzymatic hydrolysis rate and yield of fermentable sugars. Some influence factors including dosage of straw, particle size of straw meal as well as pretreatment time and temperature were investigated. After optimization,the hydrolytic efficiency of regenerated straw increased obviously as compared to untreated materials, and the sugar yield of straw was 71.2% after pretreatment in [AMIM]Cl at 110 oC for 1.5 h with a 3 w/w% straw dosage, 3.6 times higher than that of untreated straw (19.6%). The reason behind the acceleration of enzymatic hydrolysis was discussed by the analysis of SEM, XRD and FTIR. The yield of bacterial cellulose obtained in straw hydrolysates was higher than that in glucose-based media. This may be due to the presence of other complex components in the hydrolysate that would enhance the formation of bacterial cellulose.

Optimization of cultivation conditions for lipase production and the preparation of a specific lipase catalyzing the hydrolysis of polyethylene terephthalate (PET) by Aspergillus oryzae CCUG 33812 as well as modification of PET fabrics by the enzyme were investigated. The lipase activity produced by the fungus after addition of olive oil was not efficient in changing the properties of PET samples. In order to obtain lipase activity directed towards hydrolysis of PET, two derivatives of terephthalic acid (TPA), namely diethyl p-phthalate (DP) and bis(2-hydroxyethyl) terephthalate (BHT), and PET short fibers were used as inducers. The results showed that BHT was the best inducer. The BHT-induced extracellular lipase could catalyze hydrolysis of the PET model substrate diethyl p-phthalate. The formation of new carboxyl groups is consistent with the increase in K/S values of dyed PET fabrics after the enzymatic treatment. Additionally, treatment with the BHT-induced lipase resulted in increased moisture regain and weight loss of PET fiber/fabric, while the water contact angle and the static half decay time decreased slightly. This indicates that hydrophilicity and anti-static ability were improved after the treatment with the BHT-induced lipase. Compounds that were solubilized by the enzymatic treatment were analyzed by spectrophotometry and high performance liquid chromatography with UV detection. Both analyses indicated that hydrolysis of PET occurred and that products were formed due to the catalytic action of the BHT-induced enzyme, however, no significant changes in UV absorbance and no new peaks were found in HPLC-UVD analyses of reaction mixtures with olive oil-induced lipase or PET-induced lipase. This investigation has resulted in detailed procedures for production of PET-hydrolyzing lipase by A. oryzae and is the first report regarding the successful use of BHT as an inducer for the enzyme production.

In order to improve yields and to reduce the cost of oxalate decarboxylase (OxDC, EC 4.1.1.2), the induction of OxDC in the white-rot fungus Trametes versicolor was studied in this work. OxDC was induced by addition of inorganic acids including hydrochloric acid, sulfuric acid and phosphoric acid to culture media. The results showed that all the acids could enhance OxDC expression. The activity of the acid-induced OxDC rose continuously. All of the OxDC volumetric activities induced by the inorganic acids were higher than 20.0 U/L, and were two times higher than that obtained with oxalic acid. OxDC productivity was around 4.0 U•L-1•d-1. The highest specific activity against total protein was 3.2 U/mg protein at day 8 after induction of sulfuric acid and the specific activity against mycelial dry weight was 10.6 U/g at day 9 after induction of hydrochloric acid. The growth of mycelia was inhibited slightly when the pH values in culture media was around 2.5-3.0, while the growth was inhibited heavily when the pH was lower than 2.5.