Microbial pectinolytic enzymes: A review

Pectin is a high value functional food ingredient widely used as a gelling agent and stabilizer. It is also an abundant, ubiquitous and multifunctional component of the cell walls of all land plants. Food scientists and plant scientists therefore share a common goal to better understand the structure and functionalities of pectic polymers at the molecular level. The basic properties of pectin have been known for nearly 200 years, but recently there has been tremendous progress in our understanding of the very complex fine structure of pectic polymers and pectinolytic enzymes. This has been made possible by synergies between plant and food research and by the application of a range of state-of-the-art techniques including enzymatic fingerprinting, mass spectrometry, NMR, molecular modelling, and monoclonal antibodies. With this increased knowledge comes the prospect of novel applications. Producers are beginning to develop a new generation of sophisticated designer pectins with specific functionalities. Moreover, the ability to manipulate pectin in planta would have a major impact on fruit and vegetable quality and processing, as well as on pectin production.

Pectin: new insights into an old polymer are starting to gel

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.

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Microbial enzymes: industrial progress in 21st century

Bast fibres are defined as those obtained from the outer cell layers of the stems of various plants. The fibres find use in textile applications and are increasingly being considered as reinforcements for polymer–matrix composites as they are perceived to be “sustainable”. The fibres are composed primarily of cellulose which potentially has a Young’s modulus of ∼140 GPa (being a value comparable with man-made aramid [Kevlar/Twaron] fibres). The plants which are currently attracting most interest are flax and hemp (in temperate climates) or jute and kenaf (in tropical climates). This review paper will consider the growth, harvesting and fibre separation techniques suitable to yield fibre of appropriate quality. The text will then address characterisation of the fibre as, unlike man-made fibres, the cross section is neither circular nor uniform along the length.

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A review of bast fibres and their composites. Part 1 – Fibres as reinforcements

In today's world, there is an increasing trend towards the use of renewable, cheap and readily available biomass in the production of a wide variety of fine and bulk chemicals in different biorefineries. Biorefineries utilize the activities of microbial cells and their enzymes to convert biomass into target products. Many of these processes require enzymes which are operationally stable at high temperature thus allowing e.g. easy mixing, better substrate solubility, high mass transfer rate, and lowered risk of contamination. Thermophiles have often been proposed as sources of industrially relevant thermostable enzymes. Here we discuss existing and potential applications of thermophiles and thermostable enzymes with focus on conversion of carbohydrate containing raw materials. Their importance in biorefineries is explained using examples of lignocellulose and starch conversions to desired products. Strategies that enhance thermostablity of enzymes both in vivo and in vitro are also assessed. Moreover, this review deals with efforts made on developing vectors for expressing recombinant enzymes in thermophilic hosts.

https://link.springer.com/content/pdf/10.1186%2F1475-2859-6-9.pdf

Potential and utilization of thermophiles and thermostable enzymes in biorefining

Applications of pectinases in the commercial sector: a review.

An alkalophilic and thermotolerant, pectinase-producing Bacillus sp. DT7 effectively removed pectic substances from buel (Grewia optiva) bast fibres. A novel combined (chemical and enzymatic) treatment was used to degum buel bast fibres, which was followed by the release of galacturonic acid (575 μmol g−1 dry fibres) and a decrease in dry weight (43%) of these fibres.

Degumming of buel (Grewia optiva) bast fibres by pectinolytic enzyme from Bacillus sp. DT7

Penicillin G acylase (pac) gene was cloned into a stable asd+ vector (pYA292) and expressed in Escherichia coli. This recombinant strain produced 1000 units penicillin G acylase g−1 cell dry wt, which is 23-fold more than that produced by parental Escherichia coli ATCC11105. This enzyme was purified to 16 units mg−1 protein by a novel two-step process.

Enhanced production of penicillin G acylase from a recombinant Escherichia coli

Ninety seven percent of Pb 2 + and eighty five percent of Cd 2 + biosorption occurred within one minute of blosorption reaction by Acitnetobacter anitratus biomass. Maximum lead and cadmium uptake was 164 and 274 mg g - 1 dry blomass. The optimal biosorptlon was obtained at neutral pH. Among various Immobilizing matrices, sodium alginate (3%, w/v) was found to be the best for biosorption which was stable upto 10 cycles of biosorption/desorption reactions. The effective agent for desorption of Pb 2 + and Cd 2 + was found to be 0.1M EDTA. This biosorption was fitted in Freundlich adsorption model.

Pawan K. Vohra

Papers

Applications of pectinases in the commercial sector: a review.

Degumming of buel (Grewia optiva) bast fibres by pectinolytic enzyme from Bacillus sp. DT7

Enhanced production of penicillin G acylase from a recombinant Escherichia coli

Adsorption of heavy metals (Pb2+ and Cd2+) by free and immobilized biomass of Acinetobacter anitratus