Phenotypic characterization of culturable marine luminous bacteria isolated from coastal waters of the southern Adriatic Sea (Otranto, Italy)

F Bagordo,A Idolo,F Serio,G Gabutti,F Lugoli,A De Donno,T Grassi

doi:10.7773/cm.v38i4.2119

Abstract

To determine the abundance and species composition of luminous bacteria in the coastal waters of the southern Adriatic Sea (Otranto, Italy), samples were collected from three sites affected by different degrees of anthropogenic pollution. A total of 116 strains of marine luminous bacteria were isolated and subjected to phenotypic characterization, which included 36 biochemical tests. Numerical analysis of the data revealed five clusters with > 86% similarity, which were readily identified as Photobacterium leiognathi, Vibrio fischeri, Vibrio harveyi, Vibrio splendidus biovar I, and Shewanella hanedai. The relative abundance of each species shows that culturable luminous bacteria in the monitored waters are composed mainly of V. harveyi (69.0%), followed by V. fischeri (13.8%) and P. leiognathi (12.1%). In addition, human activity appears to affect the total abundance of luminous bacteria but not the selection of individual species, since the frequencies of the bacteria were similar at all examined sites.

Highlights

Luminescent bacteria (LB) are grouped as a functional unit on the basis of their ability to emit visible light
Viable heterotrophic bacteria as well as LB abundances were characterized by spatial variations, which may be related to human activities such as sewage disposal from urbanized areas and port activities
Many authors (Ramaiah and Chandramohan 1993, Bacci et al 1994, Sbrilli and Cruscanti 1999, Nocciolini et al 2000, Perego et al 2002, De Donno et al 2008, Wang et al 2009) have suggested that the abundance of marine heterotrophic bacteria and the relative luminescent fraction (LF) can be used as indicators of coastal water quality in relation to inputs of contaminants in marine environments

Summary

Introduction

Luminescent bacteria (LB) are grouped as a functional unit on the basis of their ability to emit visible light. These bacteria are occasionally found in fresh water, brackish water, and soil environments but are ubiquitous in the marine environment, occupying a variety of niches (Nealson and Hastings 1979). Marine LB have been isolated from seawater as freeliving cells or adhering to sediment and detritus (Reichelt and Baumann 1973, Ramesh et al 1990), and are widely distributed in shallow coastal environments and deep pelagic waters. Estas bacterias se encuentran ocasionalmente en agua dulce, agua salobre y suelos, pero son ubicuas en el ambiente marino, donde ocupan una gran variedad de nichos (Nealson y Hastings 1979)

Methods

Results

Conclusion