T. Panda

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 and applications of esterases

Esterase plays a major role in the degradation of natural materials and industrial pollutants, viz., cereal wastes, plastics, and other toxic chemicals. It is useful in the synthesis of optically pure compounds, perfumes, and antioxidants. The potential applications of esterase with reference to agriculture, food, and pharmaceutical industries, are discussed in this review. Promising applications in this avenue can be supported by appropriate production strategies.

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.

Regulation and cloning of microbial chitinase genes.

Abstract A range of chitinase genes from microorganisms have been cloned and the potential uses of these genetically manipulated organisms are being investigated by various researchers. Fungi and yeast are better producers of chitinase than bacteria. Since fungi grow at a slower rate, there have been efforts to clone the fungal chitinase genes into fast-growing bacteria. This review gives a brief survey of recent progress in the regulation and cloning of microbial chitinase genes. Emphasis is placed on the post-translational modification and localization of the recombinant protein in the host. Various amino acid domains are present in this protein. The mode of catalytic activity of the recombinant protein in comparison to the wild-type protein is discussed in the available literature. The different mechanisms involved in the regulation of chitinase genes from various microorganisms is discussed by the researchers. The scope of future research and conclusions yet to be obtained in this particular area are also outlined in this review.

Comparative studies on citric acid production by Aspergillus niger and Candida lipolytica using molasses and glucose.

Abstract Citric acid production by Aspergillus niger NCIM 548 and Candida lipolytica NCIM 3472 has been studied in shake culture using glucose and molasses as carbon sources. Methanol addition (3% v/v) at 40 h of fermentation enhanced the production of citric acid by Aspergillus niger whereas a reduction in citric acid production by Candida lipolytica was observed with addition of methanol. Maximum citric acid concentration of 12 kg/m3 was obtained with Aspergillus niger using molasses in the presence of methanol, while maximum citric acid concentration of 8.4 kg/m3 was obtained with Candida lipolytica using glucose without methanol. It appears that product formation by Aspergillus niger is either non-growth associated or partially growth associated depending on the substrate. Methanol addition changes the nature of product formation in case of Candida lipolytica.

Production of microbial chitinases : A revisit

Abstract Production of microbial chitinases have received increased attention in recent years due to its potential application in various fields. There has been an all around effort to increase the production of chitinases by using genetically engineered organisms and by incorporating modern fermentation techniques. This review presents a brief outline on the production of microbial chitinases which includes information on random screening and selection of chitinolytic organisms and the rationale behind the use of genetically engineered organisms. The problems and perspectives involved in large scale production of chitinases is discussed with special reference to bioreactor studies and new fermentation methods. The present limitations in the understanding of the chitinase fermentation process is also discussed and the scope for future investigation is outlined in this communication.

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.

Determination of significant parameters for improved griseofulvin production in a batch bioreactor by Taguchi's method

Abstract Taguchis method was applied to evaluate the significant parameters for griseofulvin production by Penicillium griseofulvum MTCC 1898 in a batch bioreactor. Physical parameter, viz., controlled pH, agitation and aeration had a significant influence on griseofulvin production when compared with chemical parameters and were considered as significant ones.

Studies on critical analysis of factors influencing improved production of protoplasts from Trichoderma reesei mycelium

Abstract Efficient synthesis of a large number of viable protoplasts from Trichoderma longibrachiatum (Trichoderma reesei) mycelium has been found to be influenced by a number of factors. In this case, Trichoderma harzianum NCIM 1185 culture filtrate has been used to prepare protoplasts from Trichoderma longibrachiatum QM 9414. A method has been devised to isolate a large number of viable protoplasts from the mycelium. Detailed analysis of different factors affecting the synthesis of protoplasts from T. longibrachiatum has not yet been reported. The most suitable conditions for protoplasting were as follows: age of the organism in slant, 3 days; mycelium age, 20 h; volume of lytic enzymes, 190 ml; mycelial weight (dry equivalent), 1.66 g; time of contact with lytic enzymes, 2 h; temperature of protoplasting, 30°C; phosphate buffer, 25 m m , pH 6.5; KCl as osmotic stabilizer, 0.7 m . Proper spreading of the mycelium in contact with the lytic enzymes was also found to be necessary.

Optimization of microbiological parameters for enhanced griseofulvin production using response surface methodology

Abstract Central composite design was used to determine the optimal levels of microbiological parameters, viz., slant age, seed age and inoculum level, for enhanced griseofulvin production by Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004 in shake flask fermentation. The optimal levels of slant age, seed age and inoculum level for Penicillium griseofulvum MTCC 1898 were found to be 8.8772 days, 4.2093 days, 12% (v/v) (≡17.56 kg dry cell mass/m3) and for Penicillium griseofulvum MTCC 2004, 8.221 days, 3.4875 days and 9% (v/v) (≡8.09 kg dry cell mass/m3) respectively. The yield of griseofulvin under optimal conditions was found to be 1.65 times for Penicillium griseofulvum MTCC 1898 and 1.07 times for Penicillium griseofulvum MTCC 2004 higher than that obtained using unoptimized conditions. The fermentation time for maximum production of griseofulvin by Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004 decreased by 4 days and 2 days respectively.