Chromobacterium violaceum is a gram-negative bacterium, which has been used widely in microbiology labs involved in quorum sensing (QS) research. Among the QS-regulated traits of this bacterium, violacein production has received the maximum attention. Violacein production in this organism, however is not under sole control of QS machinery, and other QS-regulated traits of this bacterium also need to be investigated in better detail. Though not often involved in human infections, this bacterium is being viewed as an emerging pathogen. This review attempts to highlight the recent research advances on C. violaceum, with respect to violacein biosynthesis, development of various applications of this bacterium and its bioactive metabolite violacein, and its pathogenicity.
Effect of a type of Indian classical music (Raag Kirwani) comprised of the sound corresponding to a frequency range of 38-689 Hz, on microbial growth, production of certain important metabolites, and antibiotic susceptibility was investigated. All the bacteria and yeasts used as test organisms were found to reg ister better (3.15-40.37% higher) growth under the influence of music, except Serratia marcescens. Music treatment was also found to affect production of bacterial pigments (prodigiosin and violacein) whose pro duction is normally linked with quorum sensing in the producing bacteria. All the test organisms exhibited an increased antibiotic susceptibility (increase ranging from 3.81-18.69%) under the influence of music. Chromobacterium violaceum and S. marcescens were found to degrade cephazolin at a faster rate when incu bated with music. Membrane permeability of the test organisms seemed to get altered owing to music treat ment. Intracellular concentration of cations (calcium and potassium) and protein content of the music treated cultures was also significantly different than the untreated control. The audible sound in form of music employed in this study was able to affect growth, metabolism, and antibiotic susceptibility of prokaryotic as well as eukaryotic microbes.
Effect of two different audible sound (music) patterns on six different microorganisms was investigated. Both the sound patterns namely Ahir Bhairav (172-581 Hz) and Piloo (86-839 Hz) were able to significantly affect microbial growth and production of certain key metabolites by the test microbes. Faster uptake of glucose from the growth medium by Brevibacillus parabrevis and Saccharomyces cerevisiae was observed under the influence of sound. Production of quorum sensing-regulated pigments, prodigiosin and violacein, respectively by Serratia marcescens and Chromobacterium violaceum was also notably affected by sound treatment. Further investigation to decipher molecular basis of microbial response to sound is warranted to understand the mechanism how audible sound interacts with microbial cells, and how the microbial population(s) modulate their behavior in response to sound stimulation.
If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to investigate various extracts of Annona squamosa L (Annonanceae) and Carica papaya L (Caricaceae) seeds for their antioxidant activity, free radical scavenging ability, total phenolic and flavonoid contents. Design/methodology/approach -Samples from both the seeds were prepared by subjecting them to microwave-assisted extraction. After determining their antioxidant properties and polyphenolic contents, correlation between them was also investigated. Findings -Highest antioxidant activity (3,179.66 g gallic acid equivalent/g of dry extract) and phenol content were registered by chloroform:methanol extract of C. papaya seeds. Maximum radical scavenging activity (3,201.63 ascorbic acid equivalent antioxidant capacity g/100 g of dry extract) was exerted by water extract of A. squamosa seeds, whereas acetone extract of C. papaya registered highest flavonoid content among all extracts. Polar extracts were found to be better free radical scavengers compared with those less polar. Hexane extracts showed least DPPH radical scavenging activity. Acetone proved efficient in extracting flavonoids, whereas phenols were best extracted in a mixture of chloroform and methanol. Phenolic metabolites seem to be contributing significantly towards antioxidant activity of the C. papaya extracts, but less so in the case of A. squamosa. Originality/value -There have been few reports on antioxidant activity of non-edible parts of commonly consumed fruits. The research indicates that seeds may be a promising source of antioxidants, which may have therapeutic implications.
This work indicates that while working with pigmented bacteria, it is important to pay attention to the absorption spectrum of the pigment(s) involved, and also to dilute the dense bacterial suspensions appropriately prior to measuring optical density, so as to avoid any major deviation of OD from the proportionality to the cell density. Besides presenting the experimental data in this paper, patents regarding measurement of cell growth, as well as those indicating the potential of commercialization of various aspects of QS research have been mentioned.
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