Volume 5 • Issue 5 • 1000209 J Veterinar Sci Technolo ISSN: 2157-7579 JVST, an open access journal Open Access Research Article Dananjaya et al., J Veterinar Sci Technolo 2014, 5:5 DOI: 10.4172/2157-7579.1000209 *Corresponding authors: Jehee Lee, Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea, Tel: +82647543472; Fax: +82647563493; E-mail: jehee@jejunu.ac.kr Mahanama De Zoysa, College of Veterinary Medicine (BK21 Plus Program) and Research Institute of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon, 305-764, Tel: +82428216795; Fax: +82428218903; E-mail: mahanama@cnu.ac.kr Received October 29, 2014; Accepted November 26, 2014; Published November 28, 2014 Citation: Dananjaya SHS, Godahewa GI, Jayasooriya RGPT, Chulhong OH, Lee J, et al. (2014) Chitosan Silver Nano Composites (CAgNCs) as Potential Antibacterial Agent to Control Vibrio tapetis. J Veterinar Sci Technol 5: 209. doi:10.4172/2157- 7579.1000209 Copyright: © 2014 Dananjaya SHS, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Nanocomposites exhibit high performance on antimicrobial activities and have the potential to be developed alternative antibiotics. In this study, antibacterial effects of chitosan silver nano composites (CAgNCs) were investigated using pathogenic Vibrio tapetis as a bacterial model. Agar disc diffusion and turbidimetric assay results showed that CAgNCs could inhibit the growth of V. tapetis in concentration depended manner. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CAgNCs against V. tapetis were 50 μg/mL and 100 μg/mL, respectively. The feld emission scanning electron microscopy (FE-SEM) images analysis of V. tapetis showed severe structural damage to cells after treating CAgNCs at 75 μg/mL compared to un-treated bacteria. Moreover, CAgNCs induce the intracellular ROS level, leakage of nucleic materials (RNA and DNA), decrease the cell viability and protein level in V. tapetis cells. Herein, we demonstrate that CAgNCs as effective antibacterial agent with capability to disrupt cell membrane, de-stabilize the membrane permeability, induce the oxidative stress and inhibit the expression of protein or synthesis of macromolecules. Overall results from this study suggest that mode of action of CAgNCs may be associated with excessive generation of ROS, loss in membrane integrity and inhibiting protein synthesis that cause the bacterial cell death. Chitosan Silver Nano Composites (CAgNCs) as Potential Antibacterial Agent to Control Vibrio tapetis Dananjaya SHS 1 , Godahewa GI 2 , Jayasooriya RGPT 2 , Chulhong OH 3 , Jehee Lee 2,4 * and Mahanama De Zoysa 1,4 * 1 College of Veterinary Medicine (BK21 Plus Program) and Research Institute of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon, 305-764, Republic of Korea 2 Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea 3 Korea Institute of Ocean Science Technology, Ansan 426-744, Republic of Korea 4 Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea Keywords: Antimicrobial agents; Vibrio tapetis; Chitosan-silver nanocomposite; Reactive oxygen species Introduction In recent years, various nanoparticles (NPs) have been developed with broad spectrum of antimicrobial properties. Silver (Ag) is considered as one of the most prominent and efective inorganic bactericidal agent in ionic form as well as in nanoparticle level [1]. One of the important characteristic features of any antimicrobial agent is that it should avoid the generation of antibiotic resistant to given target organism, hence the major advantage of Ag over the conventional antibiotics is that microbes are less likely to develop resistance against Ag. However, application of silver nanoparticles (AgNPs) should be strictly regulated due to possibility of their accumulation in various tissues over the time and cause higher toxicities to normal cells [2]. Regiel et al. [3] reported that composite form of AgNPs with polymer based matrix could be a better option to enhance antimicrobial properties at low concentrations that reduces the toxic efects. Terefore, it is important to develop biodegradable nanocomposites to get multiple benefts in controlling pathogens. Chitosan is a cationic biocompatible polysaccharide derived afer deacetylation of chitin and it has been used to synthesize wide array of composites with higher antibacterial activities [4]. Essential function of the composite is that positively charged chitosan matrix can capture negatively charged bacteria on its surface. Ten small size AgNPs create pores on bacterial cell wall which leads to rapid disintegration of bacteria and change the cell permeability [5]. Chitosan is also used as a stabilizer instead of chemical reducing agent for protecting AgNPs from agglomeration [6]. Due to unique characteristics of chitosan Ag nano composites (CAgNCs), they have become attractive candidates as antimicrobial materials and various biomedical applications such as anticancer, wound healing and vaccine delivery agents [7]. Terefore, application of CAgNCs would be a better choice for development of efcient antimicrobial agents as well as other therapeutic applications. Also, it is important to improve the physiochemical properties, efcacy, safety, and pharmacodynamic properties of CAgNCs. Moreover, understanding its functional events on bacterial inhibiting is essential to use it efectively. Several Vibrio species are considered as important pathogens in aquaculture species and cause human infections associated with the consumption of contaminated food and drinking water [8]. Among them Vibrio tapetis is a Gram negative marine bacterium responsible for the brown ring disease (BRD) in the manila clam [9]. Terefore, we have used V. tapetis as a model bacterium to understand the antibacterial efects of CAgNCs and preliminary investigation of its mode of action. In this study, stable CAgNCs were synthesized by reduction method and preliminary investigation of its antimicrobial efects and mode of action was carried out using V. tapetis as a model bacterium. Antibacterial activities of CAgNCs were investigated J o u r n a l o f V e t e r i n a r y S c i e n c e & T e c h n o l o g y ISSN: 2157-7579 Journal of Veterinary Science & Technology