Pratima Gupta

Bacterial Exopolysaccharide mediated heavy metal removal: A Review on biosynthesis, mechanism and remediation strategies

Highlights • Catastrophe of heavy metal pollution in environment is discussed in terms of remediation through bacterial Exopolysaccharide.• Biosynthesis of polymer, mechanism of action and metal remediation through polymer has been expounded deeply.• Wide range of bacterial cells and their EPS in diverse forms have been critically analyzed.• Challenges that still lie in the path of commercialization has been scrutinized.

A two-step process for efficient enzymatic saccharification of rice straw

Response surface methodology was used to optimise a two-step process of cellulase mediated saccharification of rice straw by an isolated bacterium Lysinibacillus sphaericus. CMC concentration, yeast extract, pH and incubation temperature were optimised for cellulase production using a central composite design and their optimum values were determined to be 4.3% (w/v), 2.1% (w/v), 6.2 and 45.2 °C respectively. The CMCase activity at these values was 5.16±0.07 U/ml, which was 2.5 times that of the un-optimised system. Similarly, pretreated rice straw, enzyme load, incubation time and Tween-80 concentrations were optimised for enhanced saccharification of rice straw by optimised cellulase preparations, and their optimum values were calculated as 1.84% (w/v), 40 U, 57.4 h and 0.76 mM respectively. A percent saccharification of 69.5% was reported at optimal conditions. HPLC analysis revealed that hydrolysate produced at optimal conditions of saccharification constituted 70.8% of glucose.

In vitro biocompatibility study of keratin/agar scaffold for tissue engineering.

The porous scaffold was fabricated from a binary blend of keratin/agar for tissue engineering. The miscibility of keratin and agar polymers into their blend was confirmed by Fourier transform infrared spectroscopy and X-ray diffractometer study. The scaffold fabricated from freeze extraction method resulted in a porous interconnected structure with apparent porosity 94.40±2.34%. Scanning electron microscopy study reveals the presence of interconnected pores with a pore size ranges from 50 to 300μm. The hydrophilic nature of the scaffold was confirmed by water retention capacity studies, which was observed 160±7.89%. The scaffolds tensile strength of 0.154±0.031MPa and percent of elongation at break with 16.33±2.52% justify its mechanical capability. The positive antimicrobial property and in vitro degradation was recorded for the fabricated scaffold. The in vitro biocompatibility study of the scaffolds confirms the attachment and proliferation of the cultured mammalian myofibroblast cell line. Negative cytotoxicity and a viable cell growth ensure that the fabricated scaffold can serve a potential source of biomaterial for tissue engineering and can be applicable for wound healing and skin regeneration.

Optimization of keratin/alginate scaffold using RSM and its characterization for tissue engineering

The scaffold for tissue engineering was fabricated from a binary blend of keratin/alginate. The concentration and ratio of keratin and alginate was optimized by response surface methodology in a scaffold. The structural compatibility between keratin and alginate was examined by X-ray diffractometer and Fourier transforms infrared spectroscopy. Apparent porosity of the scaffold was calculated by Archimedes principles and its observed value of was found 96.25 ± 0.04%. The pore size of the scaffold was observed in the range between 10 and 200 μm. Tensile strength (0.33 ± 0.26 MPa) and percent of elongation at break (23.33 ± 2.52%) are the reported mechanical strength of the scaffold. Positive antimicrobial activity and in vitro degradation further confirms the fabrication of a scaffold required for tissue engineering application.

Compatibility study of alginate/keratin blend for biopolymer development

The ultimate characteristics of blend film depend on the properties of its polymeric components, composition, and on the compatibility of the polymers. Binary polymer blend films of alginate (ALG) and keratin (KER) fibers (obtained from chicken feathers) were prepared by simple solution casting techniques and their compatibility properties were studied by X-ray diffraction and scanning electron microscopy. The tensile strength and percent of elongation were measured by a tensile strength tester. The results of the present studies elucidate that ALG and KER are compatible and suitable for the development of a blend film. It was found that the ALG/KER blend ratios of 90:10 and 80:20 possess characteristics to make a blend film with a high tensile strength value. The blend with composition 90:10 of ALG/KER is the one of the strongest candidates in the preparation of blending films, because it has the highest tensile strength (0.38 MPa) and percentage of elongation (59.5%) among all tested blend compositions. The blend ratio of 80:20 of ALG/KER achieves maximum compatibility, since its intensity pattern changes drastically as recorded in an X-ray diffraction study. The fabricated blend film can be a suitable candidate for a range of biomaterials such as for a drug delivery vesicle, hydrogel, and scaffolding, etc.

Study of the keratin-based therapeutic dermal patches for the delivery of bioactive molecules for wound treatment

In the present study, dressing materials were fabricated in the form of dermal patches. The keratin based biocompatible materials, namely Keratin/Alginate, Keratin/Agar, and Keratin/Gellan were developed as therapeutic dermal patches. The patches were coated with green synthesized silver nanoparticles to prevent the microbial infection and were found to be antimicrobial against pathogens. Papain was used in the patches to acquire the enzymatic cell debridement and its activity was measured by reduction rate of benzoyl-l-arginine ethyl ester. Glucose oxidase was loaded into the patches and examined to control the glycemic level in vitro for its topical application. For better wound healing, the patches were loaded with Trolox® to incorporate antioxidant properties. The patches were found mechanically efficient to sustain the material during application. The porosity and water absorption capacity of the dermal patches were investigated to ensure the maintenance of the optimum environment essential for wound treatment. To achieve the regeneration of the skin layer during wound healing, the fibroblast growth factor was loaded in the patches and it was observed that 77.77-88.89% of growth factor were released after three days of study. Thus, it can be concluded that all the three keratin based patches are suitable for preparation of dressing as they have been acquired with essential bioactivities for wound healing.

Optimization of Cellulase Production from Isolated Cellulolytic Bacterium: Comparison between Genetic Algorithms, Simulated Annealing, and Response Surface Methodology

The present study discusses optimization of cellulase production from isolated cellulolytic bacterium. A simulated annealing (SA) algorithm is proposed for optimization of these processes to achieve the desired production goal. The approach was compared to the use of evolutionary algorithms, i.e., genetic algorithms (GAs) and response surface methodology (RSM). Ochrobactrum haematophilum was identified as the isolated bacteria. Carboxymethyl cellulose (CMC) concentration, yeast extract, pH, and incubation temperature were the significant factors screened by Plackett–Burman design and further optimized using a central composite design. The optimum values obtained were CMC concentration = 4.76% (w/v), yeast extract = 2.03% (w/v), pH = 6.3, and temperature = 44.2°C. Carboxy methyl cellulase (CMCase) activity at these values was experimentally determined to be 3.55 ± 0.16 U/ml, which was 2.8 times than the unoptimized system (1.23 U/ml). The growth-associated and non-growth-associated Leudeking–Piret constants, α and β, were respectively determined to be 0.3943 and 0.0105. The Michaelis–Menten constants, Vmax and Km, were determined to be 0.67 µmol/min and 2.42 mg CMC/ml, respectively. The variable-sized SA seems to be the best alternative, outperforming the GAs, showing a fast convergence and low variability among the several runs for optimized production cellulose recovery. The SA models are found to be capable of better predictions of cellulase production. The results of the SA-based RSM model indicate that it is much more robust and accurate in estimating the values of dependent variables when compared with the GA-based RSM models and only RSM models.

Fabrication of biocompatible alginate-poly(vinyl alcohol) nanofibers scaffolds for tissue engineering applications

ABSTRACT The present study signifies promising potential of alginate-poly(vinyl alcohol) nanofiber (ALPA- nf) in the field of tissue engineering. ALPA-nfs were fabricated by electrospinning using poly(vinyl alcohol) (PVA) blended with alginate in surfactant holding aqueous medium. Strong interaction between alginate and PVA resulted into improved physical properties, improving the stability of ALPA-nfs in the aqueous medium without any significant weight loss. The solubility and swelling percentage of ALPA nanofiber mat were found to be 32.23 ± 0.95 and 295 ± 4.2 respectively after 24 h. Visualization of microstructure by scanning electron microscopy (SEM) revealed the formation of random and smooth fibers. The consecutive interaction of alginate with PVA via hydrogen bonding was confirmed by FTIR analysis. Further, the biocompatibility study of ALPA-nfs revealed its non-cytotoxic impact on pluripotent embryonic stem cells (ESCs) in-vitro, facilitating their growth comparable to that seen under native condition, and hence its suitability as potent biomaterial scaffold. Graphical Abstract