Kanika Kundu

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.

Studies on Cephalosporin-C production using immobilised cells of Cephalosporium acremonium in a packed bed reactor

Abstract The production of the β-lactam antibiotic, Cephalosporin-C in a packed bed bioreactor was studied using Cephalosporium acremonium immobilised in calcium alginate, bagasse, and silk sachets. The specific β-lactam antibiotic production rate of immobilised cells was about 120%, 125% and 133% at 100 h (free cells 100%) for calcium alginate, bagasse and silk sachets, respectively. A cells-to-carrier ratio of 3:2 was found to be optimum throughout these studies. The effect of recycle ratio indicated diffusion barriers to substrate transport.

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 inoculums 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.

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.

Design, Development and Synthesis of Novel Cephalosporin Group of Antibiotics

Cephalosporins are ┚lactam antibiotics. In cephalosporin C, four membered ┚lactam ring (which is mainly responsible for the activity) is fused with six membered dihydrothiazine ring to form the basic nucleus, 7-aminocephalosporanic acid (7-ACA) and to which ┙aminoadipic acid side chain is attached through an amide bond (Fig 1). (Mandell and Sande,1991)Although cephalosporin was found to be active against large number of pathogenic bacteria (Medeiros, 1997) but the main hindrance in its application is its low stability. Also, occurrence of bacterial strains that are resistant to already existing antibiotics such as methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant E. faecalis (VRE) has led to the search of new semisynthetic cephalosporins with better solubility and new mechanism of action. Only cephalosporin C is found naturally, so it’s chemical modification allowed production of a whole series of semisynthetic cephalosporins which can be used as therapeutics to fight organisms that have become penicillin resistant. Chemical modifications of cephalosporin C resulted in new cephalosporin derivatives. These semisynthetic cephalosporins are classified based on their activity profile, the antibacterial spectrum. Each newer generation of cephalosporin has significantly greater Gram –ve antimicrobial properties than the preceding generations, (Stan,2004; Jones,1994; Jacoby,2000; Babini and Livermore, 2000) in most cases with decreased activity against Gram +ve organism. Fourth generation cephalosporins are known to have true broad spectrum activity. (Wilson,1998; Tzouvelekis et al., 1998) In the past decade, even though the cephalosporin antibiotics have made remarkable progress and contribution in the treatment of acute diseases originated from pathogenic infection in clinics, many efforts still exist to achieve the well balanced broad spectrum and to improve beta-lactamase stability. 7┙formamido cephalosporins were isolated as fermentation product of various gram negative bacteria. The development of a new antibiotic focuses mainly with the study and characterization of its mechanism of its activity (Table 1). The ┚-lactam antibiotics like penicillin, cephalosporins, vancomycin, etc. are specific inhibitor working against bacterial cell wall (peptidoglycan) synthesis but newer strains have ┚-lactamase activity which destroys most of the ┚-lactam antibiotics and thus make them resistant to it. However, cephalosporins proved to be more stable to ┚-lactamase. Cephalosporin-C (CPC) shows similarity to in structure with the penicillin in having an acyl side chain attached to an

Biosynthesis of Cephalosporin-C Acylase Enzyme: Optimal Media Design, Purification, and Characterization

Abstract: 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.

Microbial Production of 7-Aminocepahlosporanic Acid and New Generation Cephalosporins (Cephalothin) by Different Processing Strategies

The development of β-lactam antibiotics has been a continious battle of the design of new compounds to withstand inactivation by the ever-increasing diversity of β-lactamases. Semisynthetic cephalosporins like cephalothin were synthesized from 7-Amino cephalosporanic acid (7-ACA), and thiophene-2-actetic 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 23 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°C, respectively. The structural analog compound similar to the side-chain of semisynthetic cephalosporins, e.g., thiophene-2-actetic acid, was added. HPLC data analysis indicate that the concentration of cephalothin was 1.6 mg/mL.

Sustainable and Effectual Bio Fabrication of Gold Nanoparticles for Screening of Milk Adulteration

Sustainable and Effectual Bio Fabrication of Gold Nanoparticles for Screening of Milk Adulteration In the present scenario, the amelioration of bio fabrication of nanoparticles has been extensively studied to overcome the harmful effects of chemical synthesis. Gold nanoparticles have found eminence in food and pharmaceutical industries due to their unique physico-chemical properties as well as their inert nature. The present work focuses upon less-stringent, non toxic and eco-friendly biosynthesis of Gold nanoparticles by Aspergillus versicolor as a reducing agent. An efficient approach for fungal growth was discussed wherein the biomass was cultivated under non-limiting conditions, followed by addition of gold salt solution. Production of gold nanoparticles has been successfully achieved using Aspergillus versicolor and the change of biomass colour from colourless to maroon was achieved within 18 hours of incubation period. Cyclic Voltammetry studies were conducted to show to the reducing efficiency of the strain. UV-Vis Spectroscopy studies of blank Czapek Dox media revealed no characteristic peak near the 540 nm range indicating no extracellular synthesis (as per no change in media colour) and only intracellular Gold Nanoparticle formation. FT-IR analysis confirmed the presence of peaks which were ascribed to functional groups of NH2, O-H, C=O, C-N, N-H, C-Cl and C-Br. The XRD results revealed varied particle sizes of 29.22 nm, 18.9 nm, 20.43 nm, 16.04 nm, 15.26 nm Gold nanoparticles. SEM results depicted the irregular spherical shape and morphology of the intracellularly adhered gold nanoparticles. The role of pH was emphasized in the mechanistic aspects of nanoparticle formation. Further, the efficacy of the gold nanoparticles was evaluated to screen varied concentrations of melamine adulteration in milk samples. Melamine is a common adulterant in milk and milk products, especially in baby foods leading to several cases of renal failure. To the best of our knowledge, this is the first report on screening of milk adulteration by biologically synthesized gold nanoparticles.

Antimicrobial peptide Microcin C7 as an alternative drug candidate against Diphtheria toxin

Due to increase in the incidences of drug resistant pathogens, there is a need for the development of alternative drugs against which the microorganisms will not be able to develop resistance. The most promising candidates to be developed as alternative drugs are the antimicrobial peptides. In the present study the antimicrobial peptide Microcin C7 was docked with the catalytic domain of Diphtheria toxin and further the simulational studies were performed to find the stability of the complex. The results were significant and hence it was predicted that further work can be done on antimicrobial peptide to develop it as an alternative drug against Diphtheria toxin.