Effect of carbon sources on the synthesis of pectinase by Aspergilli

Purification and biochemical properties of microbial pectinases—a review

Abstract: Pectinases are a complex group of enzymes that degrade various pectic substances present in plant tissues. Pectinases have potential applications in fruit, paper and textile industries. Apart from these industrial applications, these enzymes possess biological importance in protoplast fusion technology and plant pathology. Since applications of pectinases in various fields are widening, it is important to understand the nature and properties of these enzymes for efficient and effective usage. For the past few years, vigorous research has been carried out on isolation and characterization of pectinases. New affinity matrices with improved characteristics and affinity-precipitation techniques have been developed for purification of pectinases. Recently much attention has been focused on chemical modification of pectinases and their catalytic performance by various researchers. These studies are helpful in determining key amino acid residues responsible for substrate binding, catalytic action, and physico-chemical environmental conditions for maximum hydrolysis. This short review highlights progress on purification and understanding the biochemical aspects of microbial pectinases.

Production of pectolytic enzymes – a review

Abstract: Pectolytic enzymes play an important role in food processing industries and alcoholic beverage industries. These enzymes degrade pectin and reduce the viscosity of the solution so that it can be handled easily. These enzymes are mainly synthesized by plants and microorganisms. Aspergillus niger is used for industrial production of pectolytic enzymes. This fungus produces polygalacturonase, polymethylgalacturonase and pectinlyase. This review mainly concerns with the production of pectolytic enzymes using different carbon sources. It also deals with the effect of operating parameters such as temperature, aeration rate, agitation and type of fermentation on the production of these enzymes.

Optimising growth conditions for the pectinolytic activity of Kluyveromyces wickerhamii by using response surface methodology.

Abstract: This present study was undertaken to find optimum conditions of pH, temperature and, period of incubation for the pectinolytic activity of Kluyveromyces wickerhamii isolated from rotting fruits and to assess the effect of these factors by use of response surface methodology (RSM). A central composite rotatable design was used as an experimental design for the analysis of the allocation of treatment combinations. A second order polynomial regression model was fitted and was found adequate, with an R(2) of 0.94469 (P<0.001). The effects of temperature and pH were the most significant factors in influencing enzyme production. Estimated optimum conditions were as follows: pH 5.0, temperature, 32 degrees C and an incubation period of 91 h. Pectinesterase (PE), pectin lyase (PL), and cellulase activities were not detected. Pectinase production was partially constitutive. Pectin was degraded by the isolated strain of K. wickerhamii in the current study, and the pectinolytic activity is referred to as polygalacturonase (PG) activity. Crude enzyme extract was thermostable at various temperatures and, stimulated by the presence of Ca(2+) ions but inhibited by other ions like Mg(2+), Zn(2+), Co(2+), Mn(2+) and Na(+).

Utilisation of whole wheat flour for the production of extracellular pectinases by some fungal strains

Abstract: The possibility of producing pectinases by Rhizopus stolonifer and Aspergillus awamori, using cereal raw materials as substrate, was investigated. The whole wheat flour acted as a good nutrient source for the cultivation of the microorganisms and exo- and endo-polygalacturonases (PG) were produced in submerged culture. In this respect, it was possible to obtain polygalacturonase activities at an acceptable yield, in comparison with a typical defined medium described in the literature for pectinase production. The synthesis of both enzymes occurred in both strains in the absence of pectin, demonstrating the constitutive nature of these enzymes; nevertheless, production was increased by the addition of a small amount of pectin to the flour.

Multiresponse analysis of microbiological parameters affecting the production of pectolytic enzymes by Aspergillus niger: a statistical view

Abstract: The effect of microbiological parameters, viz., slant age, inoculum age and amount of inoculum were studied using response surface methodology for the production of pectolytic enzymes, polymethylgalacturonase, polygalacturonase and pectinlyase. The central composite design was used to determine the individual optimum values. Individual optimum values of slant age, inoculum age and amount of inoculum were 49.5 h, 52.3 h and 11.2%, respectively, for polymethylgalacturonase; 62.4 h, 60.5 h and 14.4%, respectively, for polygalacturonase, and 78.3 h, 52.5 h and 13.4%, respectively, for pectinlyase. In order to develop a two-stage inoculum possessing the best conditions for the maximum production of all three enzymes, a multiresponse analysis was carried out using a generalized distance approach. The microbiological parameters were optimized simultaneously for maximum production of enzymes. The simultaneous optimal values of slant age, inoculum age and amount of inoculum were 81.4 h, 66.7 h and 15.8%, respectively, for all the three enzymes. After optimization, the fermentation time was reduced from 144 to 120 h.

Assay methods for pectic enzymes

Abstract: Publisher Summary The characterization and purification of a pectic enzyme is often complicated by the presence of other pectic enzymes produced by the source microorganism. This chapter describes three assay procedures that address this problem. Pectic enzymes from Erwinia spp. is used as examples in the chapter. The assays are readily adapted to the analysis of pectic enzyme complexes of other organisms and can be used with crude preparations. Results from plant tissue extracts should be interpreted cautiously, however, because of the prevalence of pectic enzyme inhibitors. The activity stains in the first procedure enable rapid approximation of the number and type of pectic enzymes in the sample and can guide purification strategies, particularly when used in conjunction with titration curves. The second and third procedures permit quantitative assay of hydrolytic and β-eliminative pectic enzymes, respectively. The action patterns of purified pectic enzymes are determined by viscometric and reaction product analyses; oligogalacturonides are resolved by paper chromatography or thin-layer chromatography and detected with bromphenol blue or thiobarbituric acid spray reagent.

Effects of different carbon sources on the synthesis of pectinase by Aspergillus niger in submerged and solid state fermentations

Abstract: A study was made to compare the production of pectinase by Aspergillus niger CH4 in solid-state (SSF) and submerged (SmF) fermentations. Production of endo- (endo-p) and exo-pectinase (exo-p) by SSF was not reduced when glucose, sucrose or galacturonic acid (up to 10%) were added to a culture medium containing pectin. Moreover, both activities increased when concentrations of the carbon sources were also increased. In SmF, these activities were strongly decreased when glucose or sucrose (3%) was added to culture medium containing pectin. The addition of galacturonic acid affected endo-p activity production to a lesser extend than exo-p. Final endo-p and exo-p activities in SSF were three and 11 times higher, respectively, than those obtained in SmF. The overall productivities of SSF were 18.8 and 4.9 times higher for endo-p and exo-p, respectively, than those in SmF. These results indicate that regulatory phenomena, such as induction-repression or activation-inhibition, related to pectinase synthesis by A. niger CH4 are different in the two types of fermentation.

Strain and process for production of polygalacturonase

Abstract: A process was developed for the production of polygalacturonase (poly-1,4-α-d-galacturonide glycanohydrolase, EC 3.2.1.15) by Aspergillus niger VTT-D-77050 and its mutant VTT-D-86267. High levels of production were obtained in laboratory fermentations on a beet extraction waste medium. The yields were lower in pilot scale production experiments, although the producing strains were stable in the process conditions. The enzyme mixture produced in one pilot fermentation was used successfully for improving the cloud stability of fruit nectars. In addition to polygalacturonase, the preparation also contained appreciable levels of some other important activities.

Research on pectin depolymerases in the sixties ‐ a literature review

Abstract: This review deals mainly with the literature which has appeared since the discovery of pectin lyases in 1960. Those papers have been selected which are reports of investigations carried out with purified enzyme preparations and rather well defined substrates. According to their action on high polymer pectic substances, the enzymes are placed in one of six different groups. Mutual relationships of some of the groups are discussed. It is emphasized that the choice of substrates and reaction conditions, as well as that of methods of analysis, to a large extent influence the values found for a number of enzyme properties. Trends for future research are outlined.

Catabolite repression of hydrolases in Aspergillus niger

Abstract: A comparative study was made on catabolite repression of acid protease and polygalacturonase in an adenine-requiring mutant of Aspergillus niger. Both enzymes are inducible and accumulated extracellularly after cessation of growth caused by adenine starvation. Addition of glucose, fructose, or intermediates of glycolysis, but not tricarboxylic acid cycle intermediates, depressed the formation of both enzymes. Catabolite repression of polygalacturonase by glucose occurred quickly and was almost complete. However, acid protease was only partly repressed even after several hours. Formation of polygalacturonase in the presence of actinomycin S3 or during deinduction was repressed by glucose, whereas that of acid protease was not. In the course of induction of acid protease by peptone, glucose did not affect the length of the induction lag period and the rate of acid protease formation decreased by glucose was not restored by the addition of large amounts of inducer. From these results, we suggest that catabolite repression of polygalacturonase occurs at the level of translation and that of acid protease at transcription.