In situ development of nanosilver-impregnated bacterial cellulose for sustainable released antimicrobial wound dressing.

PURPOSE: Bacterial cellulose (BC) is an interesting biomaterial found application in various fields due to its novel characteristics like purity, water holding capacity, degree of polymerization and mechanical strength. BC as wound dressing material has limitation because it has no antimicrobial activity. To circumvent this problem, the present study was carried out by impregnation of silver on bacterial cellulose surface. METHODS: Bacterial cellulose was produced by Gluconoacetobacter hansenii (strain NCIM 2529) by shaking culture method. The sodium borohydride and classical Tollens reaction was used for silver nanoparticle synthesis. RESULTS: The effectiveness of sodium borohydride method compared with Tollens reaction was evaluated on the basis of silver nanoparticle formation and its impregnation on BC as evidenced by UV-Vis spectrum analysis, FE-SEM-EDS analysis and FT-IR spectrum. The potential of nano silver impregnated BC was determined for sustained release antimicrobial wound dressing material by swelling ratio, mechanical properties and antimicrobial activity against Staphylococcus aureus. CONCLUSIONS: Thus the nanosilver impregnated bacterial cellulose as promising antimicrobial wound dressing material was evidenced.

Bacterial cellulose of Gluconoacetobacter hansenii as a potential bioadsorption agent for its green environment applications.

Bacterial cellulose (BC) is an interesting biopolymer produced by bacteria having superior properties. BC produced by Gluconoacetobacter hansenii (strain NCIM 2529) under shaking condition and explored for its applications in dye removal and bioadsorption of protein and heavy metals. Purity of BC was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) analysis. BC removed azo dye and Aniline blue (400 mg/L) with 80% efficiency within 60 min. The adsorption and elution of Bovine serum albumin (BSA) and heavy metals like lead, cadmium and nickel (Pb(2+), Cd(2+) and Ni(2+)) was achieved with BC which confirms the exclusion ability with reusability. The BSA adsorption quantity was increased with increase in protein concentration with more than 90% adsorption and elution ratio. The effect of pH and temperature on BSA adsorption has been investigated. Bioadsorption (82%) and elution ratio (92%) of BC for Pb(2+) was more when compared with Cd(2+) (41 and 67%) and Ni(2+) (33 and 85%), respectively. BC was also explored as soil conditioner to increase the water-holding capacity and porosity of soil. The results elucidated the significance of BC as renewable effective ecofriendly bioadsorption agent.

Investigation of Bacterial Cellulose Biosynthesis Mechanism in Gluconoacetobacter hansenii.

The present study explores the mechanism of cellulose biosynthesis in Gluconoacetobacter hansenii. The cellulose synthase enzyme was purified as membrane fraction and solubilized by treatment with 0.1% digitonin. The enzyme was separated by native-gel electrophoresis and ß -D-glucan analysis was carried out using in vitro gel assay. The cellulose synthase has glycoprotein nature and composed two polypeptide subunits of 93 KDa and 85 KDa. The confirmation of ß -1,4-glucan (cellulose) was performed in whole and hydrolyzed monomeric sugar form. Tinopal and Congo red were used for cellulose detection on the gel. Thus the in vitro cellulose synthesis assay with cell free enzyme fraction was attempted to improve the understanding of cellulose biosynthesis.

Physical, structural, mechanical and thermal characterization of bacterial cellulose by G. hansenii NCIM 2529.

The present study aims to investigate the physico mechanical, structural and thermal properties of the bacterial cellulose (BC) produced under shaking condition. Formation of characteristic cellulose sphere has been characterized by light and scanning electron microscopy. The purity of bacterial cellulose was confirmed by thin layer chromatography of hydrolyzed product and elemental analysis by Energy Dispersive Spectroscopy and Fourier transform infrared spectroscopy. High crystallinity bacterial cellulose (81%) composed by high Iα confirmed by X-ray diffraction and solid state C13 nuclear magnetic resonance spectroscopy. The Z-average particle size was 1.44 µm with high porosity of 181.81%. The water holding and absorption capacity was determined. Tensile strength reveals a Young's modulus of 15.71 ± 0.15 MPa and tensile strength of up to 14.94 MPa. The thermal behavior evaluated by thermogravimetry and differential scanning calorimetry shows the thermal stability of bacterial cellulose. The results demonstrated unique characteristics of bacterial cellulose produced at shaking condition.

Enhanced production of bacterial cellulose by using Gluconacetobacter hansenii NCIM 2529 strain under shaking conditions.

Bacterial cellulose (BC), a biopolymer, due to its unique properties is valuable for production of vital products in food, textile, medicine, and agriculture. In the present study, the optimal fermentation conditions for enhanced BC production by Gluconacetobacter hansenii NCIM 2529 were investigated under shaking conditions. The investigation on media components and culture parameters revealed that 2 % (w/v) sucrose as carbon source, 0.5 % (w/v) potassium nitrate as nitrogen source, 0.4 % (w/v) disodium phosphate as phosphate source, 0.04 % (w/v) magnesium sulfate, and 0.8 % (w/v) calcium chloride as trace elements, pH5.0, temperature 25 °C, and agitation speed 170 rpm with 6 days of fermentation period are optimal for maximum BC production. Production of BC using optimized media components and culture parameters was 1.66 times higher (5.0 g/l) than initial non optimized media (3.0 g/l). Fourier transform infrared spectroscopy spectrum and comparison with the available literature suggests that the produced component by G. hansenii in the present study is pure bacterial cellulose. The specific action of cellulase out of the investigated hydrolytic enzymes (cellulase, amylase, and protease) further confirmed purity of the produced BC. These findings give insight into conditions necessary for enhanced production of bacterial cellulose, which can be used for a variety of applications.