Bhavana V. Mohite

Prospective of Microbial Exopolysaccharide for Heavy Metal Exclusion

Metals as a resource are depleting, and on another side, it fetches serious environmental pollution causing a threat to human health and ecosystem. The heavy metal accumulation due to anthropogenic activities results in toxicological manifestation. The traditional methods of remediation are not cost effective, efficient, and ecofriendly which necessitate and motivate towards the safe, effective, and ecofriendly biological methods. The increasing presence of heavy metals in the microbial habitat compels the microbes to develop the ability to tolerate or resist the presence of heavy metals. Exopolysaccharide (EPS) production is one of the strategies of microbes to fight against metal stress. EPS is a microbial biopolymer which is generally produced under stress from harsh environment and nutrition conditions. EPSs are cell-associated or secreted outside the cell and comprised organic macromolecules such as polysaccharides, proteins, and phospholipids in addition to some non-polymeric molecules. EPSs work as competent biosorbents with an anionic reactant group that effectively sequesters cationic heavy metals by electrostatic interactions. The present paper summarizes the EPSs with its types, role, and biosynthesis and an endeavor to elucidate the interaction mechanism of EPSs with heavy metal with supportive and distinctive applications for heavy metal exclusion. The review concluded with the current challenges and future prospects to make the EPS an efficient biosorbent.

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-Based Hydrogels: Synthesis, Properties, and Applications

There is an importunate effort taking place worldwide to obtain the innovative hydrogels either from natural, synthetic, or mixed type polymers, ever since the breakthrough invention of the first hydrogel of polyhydroxy ethyl methacrylate. Predominantly the cellulose-based hydrogels attracted the attention of researchers due to its renewable, biodegradable biopolymeric nature. In comparison to plant cellulose (PC), the bacterial cellulose (BC) has been preferred due to its pure fibrous biomaterial nature, high crystallinity, ultrafine three-dimensional nanostructure network, high water absorption, superior mechanical properties, B. V. Mohite · S. H. Koli School of Life Sciences, North Maharashtra University, Jalgaon, Maharashtra, India S. V. Patil (*) School of Life Sciences, North Maharashtra University, Jalgaon, Maharashtra, India North Maharashtra Culture Collection Centre, North Maharashtra University, Jalgaon, Maharashtra, India e-mail: satish.patil7@gmail.com # Springer International Publishing AG, part of Springer Nature 2018 Md. I. H. Mondal (ed.), Cellulose-Based Superabsorbent Hydrogels, Polymers and Polymeric Composites: A Reference Series, https://doi.org/10.1007/978-3-319-76573-0_2-1 1 biocompatibility, and biodegradability. These promising valuable properties of BC exploit its use especially in hydrogel form in a variety of technological fields like a development of new bacterial cellulose-based hydrogels. The present review focused on its current synthesis methods and use in biomedicine, pharmaceutical, environment, agriculture, etc. In recent years BC itself and in combination have become the subject of intensive studies for the synthesis of hydrogels in search of properties and applications of BC-based hydrogels. On the whole, the review after introducing BC production and its properties discusses the synthesis of BC-based smart hydrogels with various composite materials, formation mechanism, and improved characters. The latest use of BC-based hydrogels in both well-established and innovative high-tech fields is emphatically reviewed. The review concludes with the need for future research with some suggestions for BC-based hydrogels to be commercialized as a smart biomaterial.

Phytosynthesized Gold Nanoparticles-Bacillus thuringiensis (Bt–GNP) Formulation: A Novel Photo Stable Preparation Against Mosquito Larvae

It is well-known that the sunlight irradiation damages the spores and toxin produced by Bacillus thuringiensis (Bt), which leads to loss of their insecticidal activity. This photodegradation problem is addressed in the present investigation by use of green phytosynthesized gold nanoparticles (GNP) as a photoprotectant. The efficiency of Bt with GNP before and after exposing to sunlight was evaluated against the larvae of Aedes aegypti and Anopheles subpictus. The bioassay results focused that after sunlight irradiation the Bt significantly lose their activity for Ae. aegypti (23.13%) and An. subpictus (27.08%). Although the individual GNP showed very less activity against tested larvae, it was observed that in combination with Bt it significantly enhances activity and consequently reduced the LC50 of Bt–GNP. Similarly, even after irradiation of Bt–GNP formulation, the enhanced activity was found against Ae. aegypti (23.10%) and An. subpictus (27.24%). Henceforth in the case of Bt–GNP formulation, the GNP it was not only protecting the Bt from sunlight but enhances its larvicidal potential. The interactions between the GNP and Bt toxin which might be the main reason to protect the Bt from sunlight and can help to locate the Bt toxin at the target site.

Heavy Metal Stress and Its Consequences on Exopolysaccharide (EPS)-Producing Pantoea agglomerans

AbstractCurrently, the heavy metal pollution is of grave concern, and the part of microorganism for metal bioremediation should take into account as an efficient and economic strategy. On this framework, the heavy metal stress consequences on exopolysaccharide (EPS)-producing agricultural isolate, Pantoea agglomerans, were studied. The EPS production is a protective response to stress to survive and grow in the metal-contaminated environment. P. agglomerans show tolerance and mucoid growth in the presence of heavy metals, i.e., mercury, copper, silver, arsenic, lead, chromium, and cadmium. EDX first confirmed the metal accumulation and further, FTIR determined the functional groups involved in metal binding. The ICP-AES identified the location of cell-bound and intracellular metal accumulation. Metal deposition on cell surface has released more Ca2+. The effect on bacterial morphology investigated with SEM and TEM revealed the sites of metal accumulation, as well as possible structural changes. Each heavy metal caused distinct change and accumulated on cell-bound EPS with some intracellular deposits. The metal stress caused a decrease in total protein content and increased in total carbohydrate with a boost in EPS. Thus, the performance of P. agglomerans under metal stress indicated a potential candidate for metal bioremediation. Graphical Abstractᅟ

Impact of Microbial Cellulases on Microbial Cellulose Biotechnology

Abstract Cellulose is the most abundant polymer on earth, found in nature most exclusively in plants but also produced from microorganisms in the form of microbial cellulose. Microbial cellulose is the advanced biomaterial produced from microorganisms particularly by bacteria. Microbial cellulase is the complex enzyme system that acts on cellulose and plays an important role for its utilization. A small concentration of cellulase enzyme does not impede the growth of bacterial cellulose-producing bacteria but dissolves cellulose around the cells and hence enhance the production. The significance of microbial cellulase for microbial cellulose synthesis and utilization is discussed in the present study. The reactivity of cellulase toward bacterial cellulose and its impact on production and applications like bioabsorbable bacterial cellulose and biomass for biofuel production is explored. We conclude with a need of a future direction to progress the use of microbial cellulase for microbial cellulose from a biotechnological perspective.