Ijaz Rasul

Bio: Ijaz Rasul is an academic researcher from Government College University, Faisalabad. The author has contributed to research in topics: Medicine & Bioplastic. The author has an hindex of 8, co-authored 19 publications receiving 587 citations.

Biodegradation of plastics: current scenario and future prospects for environmental safety.

Abstract: Plastic is a general term used for a wide range of high molecular weight organic polymers obtained mostly from the various hydrocarbon and petroleum derivatives. There is an ever-increasing trend towards the production and consumption of plastics due to their extensive industrial and domestic applications. However, a wide spectrum of these polymers is non-biodegradable with few exceptions. The extensive use of plastics, lack of waste management, and casual community behavior towards their proper disposal pose a significant threat to the environment. This has raised growing concerns among various stakeholders to devise policies and innovative strategies for plastic waste management, use of biodegradable polymers especially in packaging, and educating people for their proper disposal. Current polymer degradation strategies rely on chemical, thermal, photo, and biological procedures. In the presence of proper waste management strategies coupled with industrially controlled biodegradation facilities, the use of biodegradable plastics for some applications such as packaging or health industry is a promising and attractive option for economic, environmental, and health benefits. This review highlights the classification of plastics with special emphasis on biodegradable plastics and their rational use, the identified mechanisms of plastic biodegradation, the microorganisms involved in biodegradation, and the current insights into the research on biodegradable plastics. The review has also identified the research gaps in plastic biodegradation followed by future research directions.

Bacterial lipases: A review on purification and characterization.

Abstract: Lipase (E.C.3.1.1.3) belongs to the hydrolases and is also known as fat splitting, glycerol ester hydrolase or triacylglycerol acylhydrolase. Lipase catalyzes the hydrolysis of triglycerides converting them to glycerol and fatty acids in an oil-water interface. These are widely used in food, dairy, flavor, pharmaceuticals, biofuels, leather, cosmetics, detergent, and chemical industries. Lipases are of plant, animal, and microbial origin, but microbial lipases are produced at industrial level and represent the most widely used class of enzymes in biotechnological applications and organic chemistry. Phylogenetic analysis and comparison of residues around GxSxG motif provided an insight to the diversity among bacterial lipases. A variety of para-Nitrophenyl (p-NP) esters having C2 to C16 (p-NP acetate to p-NP palmitate) in their fatty acid side chain can be hydrolyzed by bacterial lipases. Large heterogeneity has been observed in molecular and catalytic characteristics of lipases including molecular mass; 19–96 kDa, Km; 0.0064–16.58 mM, Kcat; 0.1665–1.0 × 104 s−1 and Kcat/Km; 26.02–7377 s-1/mM. Optimal conditions of their working temperature and pH have been stated 15–70 °C and 5.0–10.8, respectively and are strongly associated with the type and growth conditions of bacteria. Surface hydrophobicity, enzyme activity, stability in organic solvents and at high temperature, proteolytic resistance and substrate tolerance are the properties of bacterial lipases that have been improved by engineering. Bacterial lipases have been extensively studied during last decade. However, their wider applications demand a detailed review on purification, catalytic characterization and applications of lipases.

Microbial Polyhydroxyalkanoates (PHAs): Efficient Replacement of Synthetic Polymers

Abstract: Microbial polyhydroxyalkanoates (PHAs) are biopolyesters produced by microorganisms as intracellular granules under nutrient stress. Due to non-toxic and biodegradable behavior these polyesters are a sustainable source of wide range of biomaterials such as bioplastics. As a result of excellent polymeric properties such as melting temperatures (Tm), glass transition temperature (Tg), crystallinity, Young’s modulus and stress to break ratio these polyesters are capable of replacing the synthetic plastics. Bioplastics produced using PHAs as biomass source can be used for packaging material and disposable products on the other hand biofuels can also be generated using PHAs. PHAs find countless applications in industry, agriculture, pharmaceuticals and health. A large number of bacterial, microalgal and fungal species can produce these polyesters. Bacterial species such as Bacillus megaterium, Pseudomonas aeruginosa, P. oleovorans, P. stutzeri and Cupriavidus necator are some highly studied microorganisms for PHA production. This review summarizes the most important aspects of PHAs, crystalline and granular structure of PHA biosynthesizing genes and their relevant proteins. Thermal and physical properties, sources, extraction, purification methods of PHAs are briefly discussed. Applications of PHAs, phylogenetic analysis of Pseudomonas sp. in term of its PHAs synthesizing genes, future prospects and possible outcomes are discussed.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

Abstract: Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Bacteria and archaea on Earth and their abundance in biofilms

Abstract: Biofilms are a form of collective life with emergent properties that confer many advantages on their inhabitants, and they represent a much higher level of organization than single cells do. However, to date, no global analysis on biofilm abundance exists. We offer a critical discussion of the definition of biofilms and compile current estimates of global cell numbers in major microbial habitats, mindful of the associated uncertainty. Most bacteria and archaea on Earth (1.2 × 1030 cells) exist in the ‘big five’ habitats: deep oceanic subsurface (4 × 1029), upper oceanic sediment (5 × 1028), deep continental subsurface (3 × 1029), soil (3 × 1029) and oceans (1 × 1029). The remaining habitats, including groundwater, the atmosphere, the ocean surface microlayer, humans, animals and the phyllosphere, account for fewer cells by orders of magnitude. Biofilms dominate in all habitats on the surface of the Earth, except in the oceans, accounting for ~80% of bacterial and archaeal cells. In the deep subsurface, however, they cannot always be distinguished from single sessile cells; we estimate that 20–80% of cells in the subsurface exist as biofilms. Hence, overall, 40–80% of cells on Earth reside in biofilms. We conclude that biofilms drive all biogeochemical processes and represent the main way of active bacterial and archaeal life. In this Analysis article, Flemming and Wuertz calculate the total number of bacteria and archaea on Earth and estimate the fraction that lives in biofilms. They propose that biofilms are the most prominent and influential type of microbial life.

Microbial lipases and their industrial applications: a comprehensive review

Abstract: Lipases are very versatile enzymes, and produced the attention of the several industrial processes. Lipase can be achieved from several sources, animal, vegetable, and microbiological. The uses of microbial lipase market is estimated to be USD 425.0 Million in 2018 and it is projected to reach USD 590.2 Million by 2023, growing at a CAGR of 6.8% from 2018. Microbial lipases (EC 3.1.1.3) catalyze the hydrolysis of long chain triglycerides. The microbial origins of lipase enzymes are logically dynamic and proficient also have an extensive range of industrial uses with the manufacturing of altered molecules. The unique lipase (triacylglycerol acyl hydrolase) enzymes catalyzed the hydrolysis, esterification and alcoholysis reactions. Immobilization has made the use of microbial lipases accomplish its best performance and hence suitable for several reactions and need to enhance aroma to the immobilization processes. Immobilized enzymes depend on the immobilization technique and the carrier type. The choice of the carrier concerns usually the biocompatibility, chemical and thermal stability, and insolubility under reaction conditions, capability of easy rejuvenation and reusability, as well as cost proficiency. Bacillus spp., Achromobacter spp., Alcaligenes spp., Arthrobacter spp., Pseudomonos spp., of bacteria and Penicillium spp., Fusarium spp., Aspergillus spp., of fungi are screened large scale for lipase production. Lipases as multipurpose biological catalyst has given a favorable vision in meeting the needs for several industries such as biodiesel, foods and drinks, leather, textile, detergents, pharmaceuticals and medicals. This review represents a discussion on microbial sources of lipases, immobilization methods increased productivity at market profitability and reduce logistical liability on the environment and user.

Microbial and Enzymatic Degradation of Synthetic Plastics

Abstract: Synthetic plastics are pivotal in our current lifestyle and therefore, its accumulation is a major concern for environment and human health. Petroleum-derived (petro-)polymers such as polyethylene (PE), polyethylene terephthalate (PET), polyurethane (PU), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) are extremely recalcitrant to natural biodegradation pathways. Some microorganisms with the ability to degrade petro-polymers under in vitro conditions have been isolated and characterized. In some cases, the enzymes expressed by these microbes have been cloned and sequenced. The rate of polymer biodegradation depends on several factors including chemical structures, molecular weights, and degrees of crystallinity. Polymers are large molecules having both regular crystals (crystalline region) and irregular groups (amorphous region), where the latter provides polymers with flexibility. Highly crystalline polymers like polyethylene (95%), are rigid with a low capacity to resist impacts. PET-based plastics possess a high degree of crystallinity (30-50%), which is one of the principal reasons for their low rate of microbial degradation, which is projected to take more than 50 years for complete degraded in the natural environment, and hundreds of years if discarded into the oceans, due to their lower temperature and oxygen availability. The enzymatic degradation occurs in two stages: adsorption of enzymes on the polymer surface, followed by hydro-peroxidation/hydrolysis of the bonds. The sources of plastic-degrading enzymes can be found in microorganisms from various environments as well as digestive intestine of some invertebrates. Microbial and enzymatic degradation of waste petro-plastics is a promising strategy for depolymerization of waste petro-plastics into polymer monomers for recycling, or to covert waste plastics into higher value bioproducts, such as biodegradable polymers via mineralization. The objective of this review is to outline the advances made in the microbial degradation of synthetic plastics and, overview the enzymes involved in biodegradation.