Some properties of eucalyptus kraft pulp treated with xylanase from Aspergillus niger

An Aspergillus niger isolate produced about 2500nkat xylanase/ml when cultivated in a medium containing 3% xylose. Application of the crude xylanolytic preparation to unbleached eucalyptus kraft pulp resulted in a decreased kappa number and increased brightness. Handsheets made from the xylanase-treated pulp after ECF bleaching retained good structural and mechanical characteristics.     

Leaching of petroleum refinery ash by acidophilic sulfur-oxidizing microbial cultures

Sulfur-oxidising acidophilic bacteria were obtained from weathered sulfur piles produced by a petroleum refinery. When grown on commercial sulfur the yield was 10(10)cell/g S. Sulfur conversion to sulfate was about 95% after 17 days. Cultures were also grown together with ash obtained from incinerated refinery sludge, which contained high amounts of iron. Cultures grown in ash plus sulfur gave somewhat higher values for the growth parameters (Y=1.6x10(10)cell/g S). The sulfur conversion was about 70% (after 17 days) and more than 90% of the iron present in the ash was also leached. The sulfur-reduced compound thiosulfate, determined using ion pair HPLC, was found in the presence and absence of ash although the profile was different in each case. Sulfite was only found in non-ash containing cultures, whereas tetrathionate was only formed in the presence of ash. These results are discussed with reference to the substrates used by the micro-organisms.     

Different bioreactor configurations for the decolourisation of the azo dye reactive black 5 by Geotrichum sp. CCMI 1019

Decolourisation of the azo dye Reactive Black 5 by Geotrichum sp. CCMI 1019 was studied using stirred tank reactors (STR) and two types of bubble columns (porous plate (PP) bubble column and aeration tube (AT) bubble column). For the bubble columns, the k_La increased with the gas fractional hold-up (ε_G) and the aeration rate. A linear relationship between ε_G and superficial gas velocity was obtained for all reactors. At same aeration rates, the PP bubble columns showed higher k_La and hold-up values than the AT bubble column. In the STRs, large and dense aggregates were formed which adhered to surfaces whereas bubble columns gave smaller and less compact pellets.

Manganese peroxidase and laccase were detected in the extracellular media in all reactors. However, laccase was only detected after the onset of decolourisation, suggesting that additional enzymes may be involved. Mn peroxidase activity was detected (about 46 U/ml) in both the STRs and AT bubble columns but higher values (110 U/ml) were obtained with the PP bubble columns.

Out of the three reactor systems studied, the AT bubble columns gave the most favourable results for Reactive Black 5 decolourisation. Rapid and complete colour removal was obtained throughout the visible spectrum. Bubble columns are simple in design as well as operation and may be useful for the bioremediation of textile wastewater.     

Rapid production of thermostable cellulase-free xylanase by a strain of Bacillus subtilis and its properties

A Bacillus subtilis strain isolated from a hot-spring was shown to produce xylanolytic enzymes. Their associative/synergistic effect was studied using a culture medium with oat spelts xylan as xylanase inducer. Optimal xylanase production of about 12 U ml⁻¹ was achieved at pH 6.0 and 50°C, within 18 h fermentation. At 50°C, xylanase productivity obtained after 11 h in shake-flasks, 96,000 U l⁻¹ h⁻¹, and in reactor, 104,000 U l⁻¹ h⁻¹ was similar. Increasing temperature to 55°C a higher productivity was obtained in the batch reactor 45,000 U l⁻¹ h⁻¹, compared to shake-flask fermentations, 12,000 U l⁻¹ h⁻¹. Optimal xylanolytic activity was reached at 60°C on phosphate buffer, at pH 6.0. The xylanase is thermostable, presenting full stability at 60°C during 3 h. Further increase in the temperature caused a correspondent decrease in the residual activity. At 90°C, 20% relative activity remains after 14 min. Under optimised fermentation conditions, no cellulolytic activity was detected on the extract. Protein disulphide reducing agents, such as DTT, enhanced xylanolytic activity about 2.5-fold. When is used xylan as substrate, xylanase production decreased as function of time in contrast, with trehalose as carbon source, xylanase production in maintained constant for at least 80 h fermentation.     

Rejuvenation of the midface by elevating the malar fat pad: review of technique,cases, and complications

The midface is an area where definite and consistent improvement is still hard to achieve. Vertical suspension of the malar fat pad is an effective midface lift that complements facial rejuvenation to obtain an overall appearance of youth and beauty while maintaining the personal features of the patient. To substantiate its effectiveness, the authors evaluated the complications and long-term results of the malar fat pad elevation proper and in conjunction with other facial procedures. A retrospective review of the medical records of 458 consecutive patients who underwent malar fat pad elevation by the senior author (B.C.D.) from January of 1994 to January of 2000 was conducted. Because 14 patients had their malar fat pad re-elevated, the number of midface lifts totaled 472. Of these, 437 had a combined superficial musculoaponeurotic system excision and tightening, 19 had a combined limited superficial musculoaponeurotic system plication/imbrication, and 16 had elevation of the malar fat pad only. Elevating the malar fat pad appears to be a sound, straightforward, and effective means of rendering a youthful midface. It consistently reshapes the malar eminence, softens the nasolabial fold, and rejuvenates the lower eyelid. This technique provides lasting results, with an acceptable complication rate. Facial nerve injury, in particular, was infrequent and temporary. In addition, the prehairline scar happened to be quite inconspicuous, especially in patients older than 55 years. This experience confirms that malar fat pad elevation is a safe and effective method to rejuvenate the central third of the face.     

Amino acid accumulation by an analogue sensitive mutant ofCorynebacterium glutamicum

Summary A fluoroacetate/fluoropyruvate-sensitive mutant was derived from the parent strainCorynebacterium glutamicum ATCC 21513. Accumulation of various amino acids in the fermentation broth using the two strains was compared. The FA/FP-sensitive mutant accumulated about 26.5 g/L L-lysine and 2.2 g/L aspartic acid which was about 3-fold and 10-fold respectively, more than the amount produced by the parent strain.     

Aspergilli and lignocellulosics: Enzymology and biotechnological applications

Abstract: Aspergilli are versatile ascomycetes that are able to transform at a rapid rate a wide spectrum of lignin-related aromatic compounds. While it is clear that these fungi can degrade phenolic and polysaccharide components from lignocellulosic material, the status regarding degradation of high-molecular mass lignins is controversial. This review compiles data from the literature as well as that from the authors' laboratory with the aim of clarifying this point. The main body of evidence points towards the inability of aspergilli alone to degrade lignin free of low-molecular mass contaminants. Nevertheless, the ability of this genus to efficiently degrade hemicelluloses makes it an essential participant in the complex microbial system necessary for wood decay under natural conditions. Aspergilli are known to overproduce high levels of hemicellulolytic enzymes. Out of the large array of these enzymes that act in concert to degrade lignocellulosic material, only endoxylanases of aspergilli are described in so far as these are the main activities required for enzyme-aided bleaching. The biochemical features of the endoxylanases from Aspergillus niger are briefly described as these serve to illustrate how a complex family of isozymes is necessary to deal with the structural and chemical heterogeneity of xylans. Emphasis is placed on the biotechnological applications of lignocellulosic materials transformed by aspergilli. The key application areas are biopulping and biobleaching where a reduction in the use of environmentally harmful chemicals traditionally used in the pulp and paper industry is envisaged. Waste water treatment represents another vast application area where aspergilli have been shown to be effective not only in colour removal but also in the bioconversion of potentially noxious substances into useful bioproducts.     

Decolorization of an anthraquinone-type dye using a laccase formulation

Decolorization of the dye Remazol Brilliant Blue R (RBBR) was studied, as it is representative of an important class of recalcitrant anthraquinone-type dyes. For this purpose a commercial laccase formulation (CLF) containing laccase, a redox mediator and a non-ionic surfactant was used. Small molecular weight components were removed from the CLF by gel filtration, which made it possible to compare the effect of its laccase alone. Apart from slightly better thermostability of the CLF as compared with the laccase alone, the pH and temperature profiles were similar regardless of the presence of the small molecular weight components. The laccase alone did not decolorize RBBR. A small molecular weight redox mediator (HBT) was necessary for decolorization to occur. A comparison of the kinetics of RBBR decolorization using the CLF and its laccase alone is reported. Provided that a redox mediator is included, it is suggested that laccase may be suitable for the wastewater treatment of similar anthraquinone dyes.     

Endoscopic forehead lift: review of technique,cases, and complications

Endoscopy has provided a significant improvement in the surgical rejuvenation of the upper face. It offers a minimally invasive alternative that avoids many of the undesirable effects associated with the coronal approach. The standard minimal access forehead endoscopic procedure consists of a subperiosteal undermining through three small triangular prehairline incisions. To successfully elevate the eyebrows, it is essential to release the periosteum at the level of the supraorbital rims and ablate the brow depressor muscles of the glabella. Until the periosteum reattaches itself, elevation is maintained by a temporary suspension suture between staples at the incision sites and 5 cm posterior to the hairline. The transverse closure of the triangular skin incisions achieves some additional elevation. The biplanar approach adds a partial subcutaneous undermining of the forehead to the endoscopic technique and allows plication of the frontalis muscle and excision of excess forehead skin. It is offered to patients with very ptotic eyebrows, deep transverse wrinkles, or a high forehead. The prehairline incision is a disadvantage but is tolerated quite well in older patients. The medical records of 393 consecutive patients who underwent endoscopic forehead lift from 1994 to 2000 were reviewed. Because seven patients had the endoscopic forehead lift repeated, the number of forehead endoscopies totaled 400. The complication rate was quite acceptable and did not markedly increase when a forehead lift was performed in combination with other facial procedures. The endoscopic forehead lift consistently attenuated the transverse forehead wrinkles, reduced the glabellar frown lines, and raised the eyebrows. It provided an appearance that was less tired and angry in addition to opening the area around the eyes. Long-term follow-up has shown that the endoscopic forehead lift produces lasting and predictable results.     

Substratum choice for nesting in male Nile tilapia Oreochromis niloticus

Four substrata were offered to groups of adult Nile tilapia Oreochromis niloticus (one male and two females) simultaneously: pure sand, a mixture of sand and shells, stones and no substratum. The results showed that males chose to dig nests in a lighter and more homogeneous substratum.