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Some factors affecting pectinase production from apple pomace in solid-state cultures

Abstract Some factors affecting pectinase production from apple pomace in solid-state culture (medium composition, inoculum size, temperature and type of apple pomace used) were investigated. To obtain high enzymatic activities, apple pomace requires the addition of an adequate level of organic nitrogen components like those present in peptone, yeast extract or corn-steep. Inoculum size is not critical and optimum temperature for the fermentation process is 30°C. In connection with apple-pomace quality, the sugar concentration is the most important parameter which controls pectinase yields. By using Granny Smith pomace mixtures, containing 4% of sugars, production as high as 1300 U g−1 was attained in 36 h of culture. Pectinase levels ranging from 1000 to 2000 U litre−1 of juice for 1 to 3 h were necessary to achieve clarification in three different apple juices.

Pectinase production profile of Aspergillus foetidus in solid state cultures at different acidities

SummarySolid-state cultures of a pectinase-producing fungus (Aspergillus foetidus NRRL 341) were performed under different acidic conditions. Glass bottles containing 5 g of wheat bran and 7.5 mL of 0.2, 0.3, 0.4, or 0.5 N HCl were autoclaved (15 min, 121°C), inoculated with a spore suspension appropriately diluted to achieve an initial concentration of 4 × 104 spores per gram of wet substrate (with a 60 % humidity, on wet basis) and incubated at 30°C.Time course of pH and of different pectinase activities were determined in culture extracts. Total pectinase activity (TPA), expressed in terms of viscosimetric units per gram of wet substrate (VU.g−1), was affected by the initial culture acidity. The higher the HCl concentration used, the higher the TPA achieved, but after longer cultivation times. On the other hand, when 0.5 HCl was used, no fungal growth was observed. Nevertheless, enzyme productivity increased with culture acidity. When 0.4 HCl was used, TPA reached its maximum after 36 h of cultivation (2,535 VU.g−1). With 0.2 and 0.3 N HCl, TPA was the highest at 24 h (733 VU.g−1) and at 30 h (1,860 VU.g−1) respectively.The composition of the pectinase pool was also affected by culture acidity. The higher the acidity, the lower the pectinesterase activity and the higher both the polymethylgalacturonate lyase and polygalacturonase activities.

Citrus waste: An alternative substrate for pectinase production in solid-state culture

Abstract Pectic enzyme production in solid-state culture on a laboratory scale was performed employing citrus waste as substrate. Viscosimetric activities up to 1600–1700 Ug −1 were attained after 36 h of culture on waste supplemented with yeast extract and mineral salts. Yield of pectinases was 25% higher than that achieved with the same fungal strain and culture conditions using apple pomace as a substrate.

Fungal chitinases and their biological role in the antagonism onto nematode eggs. A review

Chitin, the most abundant aminopolysaccharide in nature, is a rigid and resistant structural component that contributes to the mechanical strength of chitin-containing organisms. Chemically, it is a linear cationic heteropolysaccharide composed of N-acetyl-D-glucosamine and D-glucosamine units. The enzymatic degradation of chitin is performed by a chitinolytic system with synergistic and consecutive action. Diverse organisms (containing chitin or not) produce a great variety of chitinolytic enzymes with different specificities and catalytic properties. Their physiological roles involve nutrition, parasitism, chitin recycling, morphogenesis, and/or defense. Microorganisms, as the main environmental chitin degraders, constitute a very important natural source of chitinolytic enzymes. Nowadays, the most used method for pest and plant diseases control is the utilization of chemical agents, causative of significant environmental pollution. Social concern has generated the search for alternative control systems (i.e., biological control), which contribute to the generation of sustainable agricultural development. Interactions among the different organisms are the natural bases of biological control. Interest in chitinolytic enzymes in the field of biological control has arisen due to their possible involvement in antagonistic activity against pathogenic chitin-containing organisms. The absence of chitin in plants and vertebrate animals allows the consideration of safe and selective “target” molecules for control of chitin-containing pathogenic organisms. Fungi show appropriate characteristics as potential biological control agents of insects, fungi, and nematodes due to the production of fungal enzymes with antagonistic action. The antagonistic interactions between fungi and plant nematode parasites are among the most studied experimental models because of the high economic relevance. Fungi which target nematodes are known as nematophagous fungi. The nematode egg is the only structural element where the presence of chitin has been demonstrated. In spite of being one of the most resistant biological structures, eggs are susceptible to being attacked by egg-parasitic fungi. A combination of physical and chemical phenomena result in their complete destruction. The contribution of fungal chitinases to the in vitro rupture of the eggshell confirms their role as a pathogenic factor. Chitinases have been produced by traditional fermentation methods, which have been improved by optimizing the culture conditions for industrial processes. Although wild-type microorganisms constitute an alternative source of chitinolytic enzymes, the advances in molecular biology are allowing the genetic transformation of fungi to obtain strains with high capability as biocontrol agents. Simultaneously, a better understanding of rhizosphere interactions, additional to the discovery of new molecular biology tools, will allow the choosing of better alternatives for the biological control of nematodes in order to achieve an integrated management of the soil ecosystem.

Aspergillus kawachii produces an acidic pectin releasing enzyme activity

A pectin-releasing (protopectinase, PPase) activity was found in a culture filtrate of Aspergillus kawachii IFO 4308. PPase activity was highest in the pH range of 2.0-2.5 and it was highly stable at 50 degrees C (85% of residual activity was found after a 10-h incubation in citrate-phosphate buffer, pH 3.0). Among other different enzyme activities, which are usually involved in plant cell-wall degradation, only polygalacturonase activity was detected. This result suggests that the PPase activity could correspond to a particular kind of polygalacturonase. Pectin extraction from lemon peels carried out at 50 degrees C for 2 h (pH 3.5) gave yields of ethanol-precipitated pectin equivalent to 17.4% of the initial total solids contained in the peels. Thus, this enzyme activity would allow carrying out a pectin extraction process at lower reaction pHs and higher temperatures in comparison with similar reports using other PPases. These properties seem to be very interesting from the practical point of view.

Apple pomace as raw material for pectinases production in solid state culture

Abstract Apple pomace was used for pectinases production on a small scale by solid state cultures. Viscosimetric enzyme activities as high as 1062 U g−1 were attained in 48 h. Characterization of the enzymatic pool showed that it is adequate for practical purposes.

Production of Pectinolytic Enzymes by the Yeast Wickerhanomyces anomalus Isolated from Citrus Fruits Peels

Wickerhamomyces anomalus is pectinolytic yeast isolated from citrus fruits peels in the province of Misiones, Argentine. In the present work, enzymes produced by this yeast strain were characterized, and polygalacturonase physicochemical properties were determined in order to evaluate the application of the supernatant in the maceration of potato tissues. W. anomalus was able to produce PG in liquid medium containing glucose and citrus pectin, whose mode of action was mainly of endo type. The supernatant did not exhibit esterase or lyase activity. No others enzymes, capable of hydrolyzing cell wall polymers, such as cellulases and xylanases, were detected. PG showed maximal activity at pH 4.5 and at temperature range between 40°C and 50°C. It was stable in the pH range from 3.0 to 6.0 and up to 50°C at optimum pH. The enzymatic extract macerated potato tissues efficiently. Volume of single cells increased with the agitation speed. The results observed make the enzymatic extract produced by W. anomalus appropriate for future application in food industry, mainly for the production of fruit nectars or mashed of vegetables such as potato or cassava, of regional interest in the province of Misiones, Argentine.

Growth and protopectinase production of Geotrichum klebahnii in batch and continuous cultures with synthetic media

Geotrichum klebahnii ATCC 42397 produces a protopectinase (PPase-SE) with polygalacturonase (PGase) activity. The microorganism was aerobically cultivated in synthetic media. Glucose, fructose and xylose yielded the highest enzyme levels (10–11 PGase units ml−1). Galacturonic acid repressed enzyme production and no growth was obtained with disaccharides and pectin. Specific enzyme activity obtained in an O2-limited culture was similar to that found in nonlimited ones. A growth yield (Yx/s) of 0.49 g of cell dry weight per gram of glucose consumed was obtained in a typical batch bioreactor culture. Enzyme production was growth associated, and no major products other than biomass and CO2 were detected. The volumetric enzyme activity reached a maximum around D=0.3–0.4 h−1 in glucose-limited continuous cultures. However, it varied strongly (together with microorganism morphology) even after retention times ≥8 at any D tested (0.035–0.44 h−1) though the rest of the culture variables remained fairly constant. No correlation between morphology and enzyme activity could be obtained. Enzyme production was poor in urea- and vitamin-limited continuous cultures. In all cases, biomass and CO2 accounted for ≅100% of carbon recovery though Yx/s values were different. Journal of Industrial Microbiology & Biotechnology (2000) 25, 260–265.

Immobilized keratinase and enrofloxacin loaded on pectin PVA cryogel patches for antimicrobial treatment

A keratinase isolated from Paecilomyces lilacinus (LPS #876) was tested against proteins present in the skin but the high enzyme activity was detected on collagen. Keratinase was physically immobilized onto PVA-pectin cryogels and enzyme release was 20.8±2.1%, 63.8±0.2%, 41.5±3.5% and 26.0±3.5% in cryogels containing pectins with esterification degrees (DE) 33.0%, 55.0%, 62.7% and 71.7% respectively at 37°C after 3h incubation. In presence of 0.75 M NaCl, the percentage of enzyme release changed to: 57.5±1.5, 65.8±3.8, 57.3±0.2 and 34.0±4.0 for the four pectins respectively. In-vitro studies of enrofloxacin release from PVA-pectin cryogels at pH close to the human skin (pH=5.5) showed 15.0% free antibiotic following first order kinetic at 37°C after 5h incubation. However, in the presence of keratinase only 6.9% of enrofloxacin was released under the same experimental conditions.

Extracellular enzymes of Fusarium graminearum isolates

Fusarium graminearum isolates from three different agroecological regions in Argentina were examined according to the production of different extracellular enzyme activities of potential biotechnological interest: pectinases (PGase: polygalacturonase and PMGase: polymethylgalacturonase), cellulase (CMCase: carboxymethylcellulase) and hemicellulase (xylanase). The isolates were grown in minimum salt medium supplemented with 0.25% glucose, 0.125% citric pectin and 0.125% oat bran as carbon sources and/or enzyme inducers. PGase activity was detected early (after two days of incubation) in all the cultures; it was found to be the highest for all the isolates. PMGase was high only for those isolates of the II region. CMCase and endoxylanase activities were particularly found at late stages (after four and seven days of incubation, respectively) and the maximum values were lower than pectinase activities.