AN ANTIMICROBIAL PHTHALATE DERIVATIVE FROM BACILLUS CEREUS, THE SYMBIOTIC BACTERIUM ASSOCIATED WITH A NOVEL ENTOMOPATHOGENIC NEMATODE, RHABDITIS (OSCHEIUS) SP

Objective: To isolate and identify the bioactive metabolites from the culture filtrates of a bacterium (Bacillus cereus) symbiotically associated with a novel entomopathogenic nematode Rhabditis (Oscheius) species.Methods: The bacterium was cultured in three different media and the antimicrobial activity was determined by the well diffusion assay. The ethyl acetate extract of the cell free culture filtrate was then purified by silica gel column chromatography and thin layer chromatography. Identification of the active metabolite was done with HPLC, GC-MS and LC-MS.Results: The cell free culture filtrate of a nematode symbiotic bacterium showed both antibacterial and antifungal activities. Fermentation conditions were standardized and optimum antibacterial activity was observed in tryptic soy broth at 72 h of incubation at 30 °C. When the ethyl acetate extract was purified by silica gel column chromatography and thin layer chromatography, an active fraction was obtained which was subjected to HPLC analysis along with GC-MS and LC-MS leading to the identification of a major compound Bis (2-ethyl hexyl) phthalate. The compound was active against Gram positive bacteria Bacillus subtilis MTCC2756, Staphylococus aureus MTCC902, Gram negative bacteria Escherichia coli MTCC 2622 and fungi such as Aspergillus flavus MTCC277, Candida albicans MTCC183, Fusarium oxysporum MTCC 284, Rhizoctonia solani MTCC 4634.Conclusion: Bis (2-ethyl hexyl) phthalate was identified as one of the metabolites produced by a nematode symbiotic bacterium associated with a novel entomopathogenic nematode Rhabditis (Oscheius) species. Thus similar compounds isolated from novel entomopathogenic bacteria would pave the way for identifying new drugs for the pharmaceutical and agricultural sector.Â

Article Variability of Carotenoids in Yellow-fleshed Cassava (Manihot esculenta Crantz) clones

Abstract Cassava (Manihot esculenta Crantz) is an important food security crop for many tropical and sub-tropical countries. Yellowfleshed tubers of cassava contain β-carotene which is a precursor of vitamin A. Out of 16 local yellow-fleshed clones, only four clones possessed moderate amount of total carotenoids ( 3.6-6.4µg/g f.wt.) and β -carotene ( 2.2-2.8 µg/g f.wt. ) coupled with good cooking quality. The analysis of 150 high carotene clones indicated that 35 clones possessed 10.0-13.6 µg total carotenoids /g f.wt. and 6 clones had 10.1-11.1 µg β -carotene /g f.wt.. There was no difference in the protein content between the white-fleshed and yellow-fleshed tubers. The studies indicated that yellow-fleshed cassava is a good source of pro-vitamin A

Synergistic Effect of Curcumin in Combination with Third Generation Cephalosporins against Bacteria Associated with Infectious Diarrhea

Diarrhea is one of the leading causes of morbidity and mortality in humans in developed and developing countries. Furthermore, increased resistance to antibiotics has resulted in serious challenges in the treatment of this infectious disease worldwide. Therefore, there exists a need to develop alternative natural or combination drug therapies. The aim of the present study was to investigate the synergistic effect of curcumin-1 in combination with three antibiotics against five diarrhea causing bacteria. The antibacterial activity of curcumin-1 and antibiotics was assessed by the broth microdilution method, checkerboard dilution test, and time-kill assay. Antimicrobial activity of curcumin-1 was observed against all tested strains. The MICs of curcumin-1 against test bacteria ranged from 125 to 1000 g/mL. In the checkerboard test, curcumin-1 markedly reduced the MICs of the antibiotics cefaclor, cefodizime, and cefotaxime. Significant synergistic effect was recorded by curcumin-1 in combination with cefotaxime. The toxicity of curcumin-1 with and without antibiotics was tested against foreskin (FS) normal fibroblast and no significant cytotoxicity was observed. From our result it is evident that curcumin-1 enhances the antibiotic potentials against diarrhea causing bacteria in in vitro condition. This study suggested that curcumin-1 in combination with antibiotics could lead to the development of new combination of antibiotics against diarrhea causing bacteria

In Vitro Synergistic Effect of Curcumin in Combination with Third Generation Cephalosporins against Bacteria Associated with Infectious Diarrhea

Diarrhea is one of the leading causes of morbidity and mortality in humans in developed and developing countries. Furthermore, increased resistance to antibiotics has resulted in serious challenges in the treatment of this infectious disease worldwide. Therefore, there exists a need to develop alternative natural or combination drug therapies. The aim of the present study was to investigate the synergistic effect of curcumin-1 in combination with three antibiotics against five diarrhea causing bacteria. The antibacterial activity of curcumin-1 and antibiotics was assessed by the broth microdilution method, checkerboard dilution test, and time-kill assay. Antimicrobial activity of curcumin-1 was observed against all tested strains. The MICs of curcumin-1 against test bacteria ranged from 125 to 1000 μg/mL. In the checkerboard test, curcumin-1 markedly reduced the MICs of the antibiotics cefaclor, cefodizime, and cefotaxime. Significant synergistic effect was recorded by curcumin-1 in combination with cefotaxime. The toxicity of curcumin-1 with and without antibiotics was tested against foreskin (FS) normal fibroblast and no significant cytotoxicity was observed. From our result it is evident that curcumin-1 enhances the antibiotic potentials against diarrhea causing bacteria in in vitro condition. This study suggested that curcumin-1 in combination with antibiotics could lead to the development of new combination of antibiotics against diarrhea causing bacteria

Protocetraric acid: an excellent broad spectrum compound from the lichen <i>Usnea albopunctata</i> against medically important microbes

<div><p>The aim of this study was to investigate the antimicrobial property of the compounds present in the lichen <i>Usnea albopunctata</i>. Ethyl acetate extract of the lichen was purified by column chromatography to yield a major compound which was characterised by spectroscopic methods as protocetraric acid. In this study, protocetraric acid recorded significant broad spectrum antimicrobial property against medically important human pathogenic microbes. The prominent antibacterial activity was recorded against <i>Salmonella typhi</i> (0.5 μg/mL). Significant antifungal activity was recorded against <i>Trichophyton rubrum</i> (1 μg/mL), which is significantly better that the standard antifungal agent. Protocetraric acid is reported here for the first time from <i>U. albopunctata.</i> Thus the results of this study suggest that protocetraric acid has significant antimicrobial activities and has a strong potential to be developed as an antimicrobial drug against pathogenic microbes.</p></div

Biocontrol of <i>Aspergillus</i> Species on Peanut Kernels by Antifungal Diketopiperazine Producing <i>Bacillus cereus</i> Associated with Entomopathogenic Nematode

<div><p>The rhabditid entomopathogenic nematode associated <i>Bacillus cereus</i> and the antifungal compounds produced by this bacterium were evaluated for their activity in reducing postharvest decay of peanut kernels caused by <i>Aspergillus</i> species in <i>in vitro</i> and <i>in vivo</i> tests. The results showed that <i>B. cereus</i> had a significant effect on biocontrol effectiveness in <i>in vitro</i> and <i>in vivo</i> conditions. The antifungal compounds produced by the <i>B. cereus</i> were purified using silica gel column chromatography and their structure was elucidated using extensive spectral analyses. The compounds were identified as diketopiperazines (DKPs) [cyclo-(L-Pro-Gly), cyclo(L-Tyr-L-Tyr), cyclo-(L-Phe-Gly) and cyclo(4-hydroxy-L-Pro-L-Trp)]. The antifungal activities of diketopiperazines were studied against five <i>Aspergillus</i> species and best MIC of 2 µg/ml was recorded against <i>A. flavus</i> by cyclo(4-hydroxy-L-Pro-L-Trp). To investigate the potential application of cyclo(4-hydroxy-L-Pro-L-Trp) to eliminate fungal spoilage in food and feed, peanut kernels was used as a food model system. White mycelia and dark/pale green spores of <i>Aspergillus</i> species were observed in the control peanut kernels after 2 days incubation. However the fungal growth was not observed in peanut kernels treated with cyclo(4-hydroxy-L-Pro-L-Trp). The cyclo(4-hydroxy-L-Pro-L-Trp) was nontoxic to two normal cell lines [fore skin (FS) normal fibroblast and African green monkey kidney (VERO)] up to 200 µg/ml in MTT assay. Thus the cyclo(4-hydroxy-L-Pro-L-Trp) identified in this study may be a promising alternative to chemical preservatives as a potential biopreservative agent which prevent fungal growth in food and feed. To the best of our knowledge, this is the first report demonstrating that the entomopathogenic nematode associated <i>B. cereus</i> and cyclo(4-hydroxy-L-Pro-L-Trp) could be used as a biocontrol agents against postharvest fungal disease caused by <i>Aspergillus</i> species.</p></div