Comparison of the hydrolysis of polyethylene terephthalate fibers by a hydrolase from Fusarium oxysporum LCH I and Fusarium solani f. sp. pisi

The hydrolysis of polyethylene terephthalate (PET) fibers by two fungal hydrolases was investigated. The hydrolase from a newly isolated Fusarium oxysporum strain (LCH 1) was more efficient in releasing terephthalic acid from PET fibers compared to the enzyme from F. solani f. sp. pisi DSM 62420 when equal amounts of p-nitrophenyl butyrate-hydrolyzing activity were employed. PET fabrics treated under the same conditions with the enzyme from F. oxysporum LCH 1 also showed a considerably higher increase in hydrophilicity compared to fabrics treated with the enzyme from F. solani f. sp. pisi DSM 62420.     

Investigation of some bioactive Thai medicinal plants

It has been estimated that plants are the most important source of medicine for more than 80% of the world’s population. Medicinal plants are a vital source of medication in developing countries. Despite the wealth of human experience and folklore concerning the medicinal uses of plants, proper scientific investigation has only been applied to a small fraction of the world’s plants. This is a cause of grave concern as plant species continue to disappear. A rapid response to this situation is urgently needed to prevent the disappearance of the plant species and the ethnopharmacological knowledge that accompanies them. In this review, recent work on the investigation of selected bioactive Thai medicinal plants is presented. Their biological activities against infectious diseases including antimalarial and anti-HIV, are highlighted, as well as their anticancer, antiulcer and anti-inflammatory properties. The chemical transformations of some selected compounds are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of sugar and amino acid supplementation on Aureobasidium pullulans NRRL 58536 antifungal activity against four Aspergillus species

Cultured cell extracts from ten tropical strains of Aureobasidium pullulans were screened for antifungal activity against four pathogenic Aspergillus species (Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, and Aspergillus terreus) using the well diffusion and conidial germination inhibition assays. The crude cell extract from A. pullulans NRRL 58536 resulted in the greatest fungicidal activity against all four Aspergillus species and so was selected for further investigation into enhancing the production of antifungal activity through optimization of the culture medium, carbon source (sucrose and glucose) and amino acid (phenylalanine, proline, and leucine) supplementation. Sucrose did not support the production of any detectable antifungal activity, while glucose did with the greatest antifungal activity against all four Aspergillus species being produced in cells grown in medium containing 2.5 % (w/v) glucose. With respect to the amino acid supplements, variable trends between the different Aspergillus species and amino acid combinations were observed, with the greatest antifungal activities being obtained when grown with phenylalanine plus leucine supplementation for activity against A. flavus, proline plus leucine for A. terreus, and phenylalanine plus proline and leucine for A. niger and A. fumigatus. Thin layer chromatography, spectrophotometry, high-performance liquid chromatography, ¹H-nuclear magnetic resonance, and MALDI-TOF mass spectrometry analyses were all consistent with the main component of the A. pullulans NRRL 58536 extracts being aureobasidins.     

Pullulan production by tropical isolates of <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis>

Tropical isolates of Aureobasidium pullulans previously isolated from distinct habitats in Thailand were characterized for their capacities to produce the valuable polysaccharide, pullulan. A. pullulans strain NRM2, the so-called “color variant” strain, was the best producer, yielding 25.1 g pullulan l⁻¹ after 7 days in sucrose medium with peptone as the nitrogen source. Pullulan from strain NRM2 was less pigmented than those from the other strains and was remarkably pure after a simple ethanol precipitation. The molecular weight of pullulan from all cultures dramatically decreased after 3 days growth, as analyzed by high performance size exclusion chromatography. Alpha-amylase with apparent activity against pullulan was expressed constitutively in sucrose-grown cultures and induced in starch-grown cultures. When the alpha-amylase inhibitor acarbose was added to the culture medium, pullulan of slightly higher molecular weight was obtained from late cultures, supporting the notion that alpha-amylase plays a role in the reduction of the molecular weight of pullulan during the production phase.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Analysis of the products from enzymatic scouring of cotton

This article discusses the analysis of the hydrolysis products from one-step scouring of cotton using pectinase and two-step scouring of cotton using lipase then cellulase, protease then cellulase, or lipase/protease then cellulase, to improve water absorbency of cotton. UV spectrophotometric analysis indicated that the pectinase scouring process produced approximately 18-fold higher amounts of reducing sugars and galacturonic acid than any of the two-step scouring processes. The production rate of reducing sugars and galacturonic acid from most of the scouring processes showed a decrease with an increase in time. HPLC analysis revealed that the lipase/protease/cellulase scouring processes produced approximately 5-fold higher amounts of 17 amino acids than the pectinase scouring process. GC analysis for 18 fatty acids (C(8)-C(24)) revealed that three major fatty acids, palmitic acid, stearic acid, and behenic acid, were found on both the scoured and the unscoured fabrics. Scoured fabrics were tested for content of proteins, extractable components, waxes, and anionic components including pectins, and some differences among the fabric scoured with different enzyme combinations were found.     

Screening of tropical fungi producing polyethylene terephthalate-hydrolyzing enzyme for fabric modification

Microfungi were selectively isolated for production of polyethylene terephthalate (PET) fiber-degrading enzymes potentially to be used to modify the surface of polyester fabric. A range of fungi were isolated from plant surfaces and soil samples using a polycaprolactone (PCL) plate-clearing assay technique, and screened for cutinolytic esterase (cutinase) activity. Twenty-two of 115 isolates showed clearing indicating the production of cutinase. The ability of the fungi to produce cutinase in mineral medium (MM) using either potato suberin or PET (1 cm of untreated pre-washed PET fiber) fiber as substrates was assessed based on the hydrolysis of p-nitrophenyl butyrate (p-NPB). All isolates exhibited activity towards p-NPB, isolate PBURU-B5 giving the highest activity with PET fiber as an inducer. PBURU-B5 was identified as Fusarium solani based on its conidial morphology and also nucleotide sequencing from internal transcribed spacer region of the ribosomal RNA gene (rDNA-ITS). Enzymatic modification of PET cloth material properties using crude enzyme from strain PBURU-B5 showed hydrolysis of ester bonds of the PET fiber. The modification of the PET fabric resulted in increase of water and moisture absorption, and general enhancement of hydrophilicity of the fabric, properties that could facilitate processing of fabric ranging from easier dyeing while also yielding a softer feeling fabric for the user.     

Heavy oils produced by <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis>

From a survey of more than 50 diverse strains of Aureobasidium pullulans, 21 produced extracellular heavy oils. Most oil producers fell into phylogenetic clades 8, 9, and 11. Oil colors ranged from bright yellow to malachite. More than half of the strains produced oil that was fluorescent. In medium containing 5% (w/v) sucrose, oil yields ranged from 0.5 to 6 g oil/l. Strain CU 43 reached stationary growth phase at day 4 while oil yields were maximal at day 6. CU 43 produced bright yellow, highly fluorescent oil that also was visible as intracellular droplets under fluorescent microscopy. Oil was surface active, suggesting that it functions as a biosurfactant. Oil from two strains (CU 43 and NRRL Y-12974) differentially inhibited mammalian cancer cell lines. MALDI-TOF MS spectra suggested that A. pullulans strains produce a family of related oil structures.     

The current status of <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis> in biotechnology

Different strains of the saprophytic yeast-like fungus Aureobasidium pullulans (Ascomycota: Dothideales) exhibit different biochemical characteristics, while their ubiquitous occurrence across diverse habitats and environmental conditions makes them an easily accessible source for biotechnological exploitation. They are useful in agricultural and industrial applications. Their antagonistic activities against postharvest pathogens make them suitable bioagents for the postharvest preservation of fruits and vegetables, while they possess antimicrobial activities against bacteria and fungi. Additionally, A. pullulans appears to be a potent source of single-cell protein. Many strains of A. pullulans harbor a wide range of industrially important enzymes, while the trademark exopolysaccharide pullulan that they produce has been extensively studied and is currently used in many applications. They also produce poly (β-l-malic acid), heavy oil liamocins, siderophore, and aubasidan-like β-glucan which are of interest for future applications. Ongoing studies suggest that A. pullulans holds many more interesting properties capable of further potential biotechnological applications.     

Evaluation of the overall process on bioethanol production from miscanthus hydrolysates obtained by dilute acid pretreatment

In this study, dilute sulfuric acid pretreatment was performed to improve the sugars recovery from Korean Miscanthus straw. The effect of pretreatment conditions on solubilized xylose was fundamentally investigated for the efficient removal of xylan. The optimal conditions were determined using a statistical method, and were shown to be a temperature of 121.6°C, an acid concentration of 1.1%, and a reaction time of 12.8 min. The combined severity factor was shown to be 1.1 under the optimum conditions. Following the pretreatment, the solubilized xylose in liquid fraction was found to be 71.2%, and about 72.6% of the solid was recovered. After enzymatic hydrolysis, about 86.4% glucose conversion was achieved when the pretreated biomass was used as a substrate, with the conversion being improved 4-fold compared with the control (untreated). The hydrolysates, approximately 10 g/L glucose, were applied to the fermentation of Saccharomyces cerevisiae K35, and the ethanol yield was about 96%. The overall process was evaluated based on the material balance, and the results show that approximately 172 g bioethanol can be produced when 1,000 g Miscanthus straw is loaded into the process.