Sangeeta Yadav

Bio: Sangeeta Yadav is an academic researcher from Deen Dayal Upadhyay Gorakhpur University. The author has contributed to research in topics: Pectin lyase & Pectinase. The author has an hindex of 11, co-authored 32 publications receiving 524 citations.

Pectin lyase: A review

Abstract: Pectin lyase acts on the pectic substances that occur as structural polysaccharides in the middle lamella and primary cell walls of higher plants. This enzyme has potential applications in food, paper and textile industries. Since new applications of this enzyme are emerging there is a scientific need to explore the important aspects of the enzyme specifically the catalytic efficiency and possible sources. Though the research work on pectin lyase has been done for the last six decades but there is no exclusive review on pectin lyase so far available in the literature. This review tries to fill this gap by providing all relevant information exclusively for pectin lyase. The topics covered in this review are a brief description of the substrate pectin, enzymes related to pectin lyase, assay procedures, sources, purification and characterization, structural aspects, substrate specificity, molecular biology, biotechnological applications and future prospects of pectin lyases.

Purification and characterization of an alkaline pectin lyase from Aspergillus flavus

Abstract: An alkaline pectin lyase secreted by Aspergillus flavus MTCC 7589 was purified to electrophoretic homogeneity using ammonium sulphate fractionation, anion exchange chromatography on DEAE cellulose and gel filtration chromatography on sephadex G-100. The pH and temperature optima of the enzyme were found to be 8.0 and 50 °C. The enzyme was found to be stable for 24 h in the pH range 4.0–10.0. The enzyme does not loose activity up to 50 °C if exposed for 1 h. Addition of ammonium sulphate in the range of 0.1–2.0 M increased the thermostability of the enzyme, 0.6 and 1.8 M of ammonium sulphate providing complete stability at 60 and 70 °C respectively. The values of Km and kcat of the enzyme were 0.59 mg/ml and 52.2 s−1 respectively. The molecular weight was found to be 38 ± 01 kDa. The purified enzyme showed efficacy in retting of Crotalaria juncea fibers.

Purification and Characterization of Pectin Lyase Produced by Aspergillus terricola and its Application in Retting of Natural Fibers

Abstract: An indigenously isolated fungal strain identified as Aspergillus terricola with assigned fungal strain number MTCC 7588 has been used as source for pectin lyase production. The extracellular pectin lyase was purified to homogeneity from the culture filtrate of A. terricola by ion exchange and gel filtration chromatography. The determined molecular weight was 35 ± 01 kDa. The K m and k cat (turnover) values of the purified enzyme at 37 °C using citrus pectin as the substrate were found to be 1.0 mg/ml and 110.0 s−1, respectively. The pH and temperature optima of the enzyme were 8.0 and 50 °C, respectively. The retting ability of the purified pectin lyase for natural fibers viz. Cannabis sativa and Linum usitatissimum has been demonstrated for the first time.

In Silico Characterization of Alkaline Proteases from Different Species of Aspergillus

Abstract: A total of 49 protein sequences of alkaline proteases retrieved from GenBank representing different species of Aspergillus have been characterized for various physiochemical properties, homology search, multiple sequence alignment, motif, and super family search and phylogenetic tree construction. The sequence level homology was obtained among different groups of alkaline protease enzymes, viz alkaline serine protease, oryzin, calpain-like protease, serine protease, subtilisin-like alkaline proteases. Multiple sequence alignment of alkaline protease protein sequence of different Aspergillus species revealed a stretch of conserved region for amino acid residues from 69 to 110 and 130-204. The phylogenetic tree constructed indicated several Aspergillus species-specific clusters for alkaline proteases namely Aspergillus fumigatus, Aspergillus niger, Aspergillus oryzae, Aspergillus clavatus. The distributions of ten commonly observed motifs were analyzed among these proteases. Motif 1 with a signature amino acid sequence of 50 amino acids, i.e., ASFSNYGKVVDIFAPGQDILSCWIGSTTATNTISGTSMATPHIVGLSCYL, was uniformly observed in proteases protein sequences indicating its involvement with the structure and enzymatic function. Motif analysis of acidic proteases of Aspergillus and bacterial alkaline proteases has revealed different signature amino acid sequences. The superfamily search for these proteases revealed the presence of subtilases, serine-carboxyl proteinase, calpain large subunit, and thermolysin-like superfamilies with 45 representing the subtilases superfamily.

Production, purification and biochemical characterization of an exo-polygalacturonase from Aspergillus niger MTCC 478 suitable for clarification of orange juice

Abstract: Polygalacturonases (PG) represent an important member of pectinases group of enzymes with immense industrial applications A fungal strain Aspergillus niger MTCC478 was used for the production of polygalacturonase both under submerged and solid-state fermentation condition Further its production was optimized under solid-state fermentation condition with media comprising of wheat bran and tea extract Purification of an exo-PG was achieved by acetone precipitation (60–90%) and CM-cellulose column chromatography revealing 1528-fold purification with a specific activity of 3347 U/mg protein and 12% yield A relative molecular mass of purified PG was approximately 1240 kDa The pH and temperature optimum was found to be 4 and 50 °C, respectively The k cat and K m value for degradation of PGA by the purified enzyme was found to be 194 s−1 and 23 mg/mL, respectively Cu2+ was found to enhance the PG activity while Ag+ completely inhibited the enzyme activity The application of the purified PG in orange juice clarification was elucidated

Microbial enzymes: industrial progress in 21st century

Abstract: Biocatalytic potential of microorganisms have been employed for centuries to produce bread, wine, vinegar and other common products without understanding the biochemical basis of their ingredients. Microbial enzymes have gained interest for their widespread uses in industries and medicine owing to their stability, catalytic activity, and ease of production and optimization than plant and animal enzymes. The use of enzymes in various industries (e.g., food, agriculture, chemicals, and pharmaceuticals) is increasing rapidly due to reduced processing time, low energy input, cost effectiveness, nontoxic and eco-friendly characteristics. Microbial enzymes are capable of degrading toxic chemical compounds of industrial and domestic wastes (phenolic compounds, nitriles, amines etc.) either via degradation or conversion. Here in this review, we highlight and discuss current technical and scientific involvement of microorganisms in enzyme production and their present status in worldwide enzyme market.

Edible films from pectin: Physical-mechanical and antimicrobial properties - A review

Abstract: Pectin is one of the main components of the plant cell wall chemically constituted by poly α1–4-galacturonic acids. According to its degree of esterification with methanol, pectin can be classified as high methoxyl pectin or low methoxyl pectin. In food industry, pectin is listed as generally recognized as safe (GRAS) by the Food and Drug Administration and is used as gelling, stabilizing, or thickening agent in food products such as jams, yoghurt drinks, fruity milk drinks, and ice cream. Due to its biodegradability, biocompatibility, edibility, and versatile chemical and physical properties (such as gelation, selective gas permeability, etc), pectin is a suitable polymeric matrix for the elaboration of edible films intended as active food packaging. Active packaging is a packaging system which possesses attributes beyond basic barrier properties that are achieved by adding active ingredients in the packaging material and/or using functionally active polymers. When the packaging system has antimicrobial activity, the packaging limits or prevents the microbial growth by extending the lag period and reducing the growth rate of microorganisms. This review describes the main methods for elaborating pectin edible films, principal characterization techniques for determining their physical-mechanical properties, and applications of pectin edible films as antimicrobial food packaging. Finally, legislation and future trends regarding the use of pectin edible films are also discussed.

Pectin and Pectinases: Production, Characterization and Industrial Application of Microbial Pectinolytic Enzymes

Abstract: Departamento de Bioquimica e Microbiologia Instituto de Biociencias Universidade Estadual Paulista, UNESP, Avenida 24A, 1515, CEP 13506-900 Rio Claro, SP

Legume pectate lyase required for root infection by rhizobia

Abstract: To allow rhizobial infection of legume roots, plant cell walls must be locally degraded for plant-made infection threads (ITs) to be formed. Here we identify a Lotus japonicus nodulation pectate lyase gene (LjNPL), which is induced in roots and root hairs by rhizobial nodulation (Nod) factors via activation of the nodulation signaling pathway and the NIN transcription factor. Two Ljnpl mutants produced uninfected nodules and most infections arrested as infection foci in root hairs or roots. The few partially infected nodules that did form contained large abnormal infections. The purified LjNPL protein had pectate lyase activity, demonstrating that this activity is required for rhizobia to penetrate the cell wall and initiate formation of plant-made infection threads. Therefore, we conclude that legume-determined degradation of plant cell walls is required for root infection during initiation of the symbiotic interaction between rhizobia and legumes.

Homogalacturonan-modifying enzymes: structure, expression, and roles in plants

Abstract: Understanding the changes affecting the plant cell wall is a key element in addressing its functional role in plant growth and in the response to stress. Pectins, which are the main constituents of the primary cell wall in dicot species, play a central role in the control of cellular adhesion and thereby of the rheological properties of the wall. This is likely to be a major determinant of plant growth. How the discrete changes in pectin structure are mediated is thus a key issue in our understanding of plant development and plant responses to changes in the environment. In particular, understanding the remodelling of homogalacturonan (HG), the most abundant pectic polymer, by specific enzymes is a current challenge in addressing its fundamental role. HG, a polymer that can be methylesterified or acetylated, can be modified by HGMEs (HG-modifying enzymes) which all belong to large multigenic families in all species sequenced to date. In particular, both the degrees of substitution (methylesterification and/or acetylation) and polymerization can be controlled by specific enzymes such as pectin methylesterases (PMEs), pectin acetylesterases (PAEs), polygalacturonases (PGs), or pectate lyases-like (PLLs). Major advances in the biochemical and functional characterization of these enzymes have been made over the last 10 years. This review aims to provide a comprehensive, up to date summary of the recent data concerning the structure, regulation, and function of these fascinating enzymes in plant development and in response to biotic stresses.