Mycofabrication of gold nanoparticles and evaluation of their antioxidant activities.

Gold nanoparticles have found prominence in pharmaceutical applications due to their unique physical properties as well as their inert nature. Mycosynthesis of noble metal nanoparticles is less stringent and eco-friendly. In this paper, we have reported the economically-viable synthesis of gold nanoparticles, mediated by five different fungal strains Aspergillus flavus NCIM650, Phoma exigua NCIM1237, Aspergillus niger NCIM 616, Aspergillus niger NCIM 1025 and Trichoderma reesei NCIM 1186. An efficient approach for fungal growth was discussed wherein the biomass was cultivated in non-limiting conditions, followed by addition of gold salt solution. Cyclic Voltammetry studies were conducted to show the varying reducing capacities of these strains. The surface plasmon peaks for gold nanoparticles produced by Aspergillus flavus NCIM650, Phoma exigua NCIM1237, Aspergillus niger NCIM 616, Aspergillus niger NCIM 1025 and Trichoderma reesei NCIM 1186 were recorded as 536nm, 543nm, 542nm, 560nm, 537nm respectively. Based on the cyclic voltammetry studies and UV-Visible spectroscopy, transmission electron microscopy (TEM) analysis was done. Among the five strains, gold nanoparticles fabricated by Aspergillus niger NCIM 616 gave quite promising results. The antioxidant activities were evaluated using DPPH quenching assay and hydrogen peroxide assay.

Development of probiotic candidate in combination with essential oils from medicinal plant and their effect on enteric pathogens: a review.

Medicinal plants and probiotics both have very high potential in terms of their antimicrobial activity against antibiotic-resistant enteric pathogens. The probiotics being enteric microorganism do not have any parasitic effect on human beings. They have been an integral part of daily food for centuries. They have been shown to have health beneficiary properties. The probiotics retard the growth of the microorganisms, while essential oil kills them. Combining the effect of medicinal plant extract and probiotics may be a new approach due to their complementary antimicrobial effects and practically no side effects. The synergistic effect of the essential oil and probiotics will be necessarily higher than using them alone as health product.

Evaluation of immunostimulatory and growth promoting effect of seed fractions of Achyranthes aspera in common carp Cyprinus carpio and identification of active constituents.

Immunostimulatory and growth promoting properties of Achyranthes aspera seeds were studied with larvae of common carp Cyprinus carpio. Four experimental diets were prepared using raw (D1) and alcohol (D2), petroleum ether (D3) and 50% aqueous alcohol (D4) extracts of A. aspera seeds. Diet without seed served as control (D5). Fish were fed with test/control diet for 30 days and then immunized with 10 µl of c-RBC. Blood samples were collected 7 days after immunization. Survival (93 ± 3%) of fish was significantly (P < 0.05) higher in D1 diet fed group compared to others. Highest specific growth rate was found in fish fed with diet D2. Significantly (P < 0.05) higher levels of serum protein and albumin were found in D1 and D3 compared to others. Highest serum globulin level was found in D1, which was followed by D3, D2, D4 and D5. Hemagglutination titer level was 5-18 folds higher in diet D3 fed fish compared to others. SGOT and SGPT levels were significantly (P < 0.05) higher in control group compared to the treated groups. Myeloperoxidase activity was significantly (P < 0.05) higher in D1 (2.513 ± 0.27 λ 450 nm) and D3 (2.38 ± 0.07 λ 450 nm) diets fed groups compared to others. The best performance of fish was found in raw A. aspera seeds incorporated diet fed group and the active constituents were identified as ecdysterone and two essential fatty acids linolenic acid and oleic acid.

Biosynthesis of cephalosporin-C acylase enzyme: optimal media design, purification, and characterization.

7-aminocephalosporanic acid (7-ACA) is the key intermediate for the synthesis of semisynthetic cephalosporin antibiotics and enzyme cephalosporin-C acylase (CPC acylase) plays an important role in the conversion of cephalosporin-C to 7-ACA. With an aim to increase the yield of 7-ACA production by Micrococcus luteus, a stepwise strategy, statistical medium was applied for optimizing the medium composition for the production of CPC acylase. Purified enzyme was found to be of 80 kDa. The optimum pH and temperature for the production of 7-ACA were 7.6 and 340C, respectively. The Km and Vmax were estimated to be 9.43 mg/mL and 7.65 U/mL, respectively.

Bioconversion of silver salt into silver nanoparticles using different microorganisms.

Abstract: Recently, silver nanoparticles have generated enough interest due to their immense usage. Until now chemical synthesis has been a fast method to produce nanoparticles, but the release of environmental pollutants has raised caution. So a more subtle biochemical approach is in research. Three microorganisms, Aspergillus flavus, Phoma exigua and Bacillus megaterium, were selected to reduce silver nitrate to silver nanoparticles in aqueous form. All three microorganisms showed varying reducing capacity, of which Phoma exigua showed the highest, when their biomass was incubated in silver nitrate for 48 hours. The nanoparticles showed all the optical and physical properties, which were analyzed by measuring the surface plasmon resonance and TEM. It was also observed that the fungal species have varied growth in silver nitrate and can be used to produce silver nanoparticles, directly incubating the inocula of fungus in the media containing silver nitrate. On comparing all the characteristics and results produced, Aspergillus flavus was found to be the most effective microorganism, which can convert the silver nitrate to silver nanoparticles in aqueous condition. The bacterial species showed no growth with incubation with silver nitrate.

Microbial production of 7-amino-cephalosporanic acid and new generation cephalosporins (cephalothin) by different processing strategies.

The development of beta-lactam antibiotics has been a continuous battle of the design of new compounds to withstand inactivation by the ever-increasing diversity of beta-lactamases. Semisynthetic cephalosporins like cephalothin were synthesized from 7-amino-cephalosporanic acid (7-ACA), and thiophene-2-acetic acid using cephalosporin-C acylase enzyme was studied. The production of cephalosporin-C acylase by Pseudomonas diminuta was used and the growth kinetics studied. The optimum condition of enzyme activity was determined by using response surface methodology. A 2(3) full-factorial composite design was employed for experimental design and the result analyzed. The pH value and temperature for optimum activity were 6.5 and 32 degrees C, respectively. The structural analog compound similar to the side-chain of semisynthetic cephalosporins, e.g., thiophene-2-acetic acid, was added. HPLC data analysis indicate that the concentration of cephalothin was 1.6 mg/mL.

Continuous production of cephalosporin-C by immobilized microbial cells using symbiotic mode in a packed bed bioreactor.

Cephalosporins are usually produced semisynthetically from Cephalosporin-C, which is exclusively produced by Cephalosporium acremonium. Free cell studies for the production of Cephalosporin-C had some limitation such as pulpy growth of fungus causing an appreciable rise in the broth viscosity affecting the transfer of oxygen and other nutrients into the cells. High cell concentrations cannot be maintained because of wash out phenomenon at high dilution rates. The whole cell immobilization technique is a potentially important process for Cephalosporin-C biosynthesis, where increase cell densities were maintained and broth-handling problems were reduced. Cephalosporin-C fermentation is a highly aerobic process. The symbiotic relationship of Cephalosporium acremonium and Chlorella pyrenoidosa has been used to increase oxygen transfer rate to the fungi by co-immobilizing it with algae. Co-immobilization of whole cells of fungus and algae were carried out in different immobilizing agents and the systems were coated with polyacrylamide resin of pharmaceutical grade to overcome the problems of leakage. The operational stability of immobilized systems in a packed bed reactor was also studied.