RESEARCH ARTICLE Bactericidal Activity of Nanopolymers Against Shrimp Pathogenic Bacterium Vibrio harveyi K. K. Krishnani • V. Kathiravan • N. A. Shakil • Manish Kumar Singh • M. P. Brahmane • K. K. Meena • Biplab Sarkar • K. Choudhary • Mukesh Kumar Singh • Jitendra Kumar Received: 28 August 2014 / Revised: 18 November 2014 / Accepted: 2 March 2015 Ó The National Academy of Sciences, India 2015 Abstract The authors have reported the use of nanopolymers for the inhibition of shrimp pathogenic bacteria for aquaculture use. The antimicrobial activity of polyethylene glycols based amphiphilic polymers have different linker molecules such as suberic acid, adipic acid, glutaric acid and dimethyl-5-hydroxyisophthalate on Vibrio harveyi. It was examined by drawing growth curves using optical density measurements. Concentration dependent antimicrobial effects of nanopolymers were tested against V. harveyi which were further confirmed by agar well diffusion for determining minimum inhibitory concentra- tions. The increased concentrations of nanopolymer ef- fectively reduced the bacterial growth and increased the diameter of inhibition zone. This study has important im- plications for disease management in coastal aquaculture. Keywords Nanopolymers  Bactericidal activity  Shrimp pathogenic bacteria  Vibrio harveyi Introduction Aquaculture is one of the most important economy in many countries. Emerging major constraints in aquaculture produc- tion are the diseases caused by bacterial strains. Vibriosis has been identified as a common problem in shrimp aquaculture, all over the world predominantly in India creating economic loss [1]. Mass mortalities in hatcheries and grow-out ponds of shrimp attributed to outbreaks of vibriosis have been recorded from many regions [2–12]. The severity of infection depends on the species and strain of Vibrio involved, the stage of devel- opment, age of shrimp, and the ambient environmental condi- tions. Over a dozen species of Vibrio have been identified as having implication in the disease process [3–5]. Six species of Vibrio i.e. V. harveyi, V. parahaemolyticus, V. alginolyticus, V. anguillarum, V. vulnificus, and V. splendidus are associated with the diseased shrimp. V. harveyi has been implicated as the main bacterial pathogen of shrimps, which is a luminous gram negative bacteria causing mortalities among Penaeus monodon larvae, post larvae and cultured shrimp [13, 14]. Vibriosis is also having its impact in grow-out ponds and is frequently respon- sible for the morbidity and mortalities of shrimp [15–17]. Vibriosis is also rampant in the Indian region where brackish- water shrimp farming is the main aquaculture activity. The disease problem is particularly severe in hatcheries, and in the past few years many units were shut down due to the invasion by luminous Vibrio [18–20]. Because luminous Vibrios effect serious mortalities in shrimp larval rearing systems [21], it is imperative that measures for their control be developed. Che- mical treatment of luminous vibriosis among shrimp larvae is quite limited because of the ineffectiveness of existing and K. K. Krishnani (&)  V. Kathiravan Central Institute of Brackishwater Aquaculture, RA Puram, Chennai 600028, Tamil Nadu, India e-mail: krishnanik@hotmail.com K. K. Krishnani  M. P. Brahmane  K. K. Meena  B. Sarkar National Institute of Abiotic Stress Management, Malegaon, Baramati (Dist Pune) 413115, India V. Kathiravan Department of Botany, Madura College, Madurai 625011, Tamil Nadu, India N. A. Shakil  M. K. Singh  M. K. Singh  J. Kumar Division of Agricultural Chemicals, Indian Agricultural Research Institute, Pusa, New Delhi, India K. Choudhary Directorate of Weed Science Research, Maharajpur, Jabalpur 482004, India 123 Proc. Natl. Acad. Sci., India, Sect. B Biol. Sci. DOI 10.1007/s40011-015-0517-x