Halomonas profundus sp. nov., a new PHA-producing bacterium isolated from a deep-sea hydrothermal vent shrimp.

AIMS: The objective of the present work was to describe a new deep-sea, aerobic, mesophilic and heterotrophic bacterium, referenced as strain AT1214, able to produce polyhydroxyalkanoates (PHAs) under laboratory conditions. This bacterium was isolated from a shrimp collected nearby a hydrothermal vent located on the Mid-Atlantic Ridge. METHODS AND RESULTS: This micro-organism, on the basis of the phenotypical features and genotypic investigations, can be clearly assigned to the Halomonas genus and the name of Halomonas profundus is proposed. Optimal growth occurred between 32 and 37 degrees C at a pH between 8 and 9 and at ionic strength between 20 and 30 g l(-1) of sea salts. The G + C content of DNA was 58.6%. This bacterium produced PHAs of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from different carbon sources. CONCLUSIONS: The bacterium H. profundus produces PHA of 3HB and 3HV monomers from different carbon sources. SIGNIFICANCE AND IMPACT OF THE STUDY: PHAs share physical and material properties that suggest them for application in various areas, and are considered as an alternative to nonbiodegradable plastics produced from fossil oils. In this study, we describe a new bacteria isolated from a deep-sea hydrothermal vent with the capability to produce polyesters of biotechnological interest.

A novel mcl PHA-producing bacterium, Pseudomonas guezennei sp. nov., isolated from a 'kopara' mat located in Rangiroa, an atoll of French Polynesia.

AIMS: The aim of the present study was to describe an aerobic, mesophilic and heterotrophic bacterium, designated RA26, able to produce a medium-chain-length polyhydroxyalkanoate (PHA). It was isolated from a French Polynesian bacterial mat located in the atoll of Rangiroa. METHODS AND RESULTS: This micro-organism, on the basis of the phenotypical features and genotypic investigations can be clearly assigned to the Pseudomonas genus and the name of Pseudomonas guezennei is proposed. Optimal growth occurs between 33 and 37 degrees C, at a pH between 6.4 and 7.1 and at ionic strength of 15 g l(-1) of sea salts. The G+C content of DNA is 63.2%. Under laboratory conditions, this bacterium produced a novel, medium-chain-length PHA, mainly composed of 3-hydroxydecanaote (64 mol.%) and 3-hydroxyoctanoate (24 mol.%) (GC-MS, NMR) from a single nonrelated carbon substrate, i.e. glucose. CONCLUSIONS: The bacterium P. guezennei produces a novel PHA mcl with elastomeric properties. SIGNIFICANCE AND IMPACT OF THE STUDY: PHAs share physical and material properties that recommend them for application in various areas, and are considered as an alternative to nonbiodegradable plastics produced from fossil oils. In this study, we describe a new bacteria with the capability to synthesize a novel PHA with promising biotechnological applications.

Induction of a protective immune response against viral nervous necrosis in the European sea bass Dicentrarchus labrax by using betanodavirus virus-like particles.

Betanodaviruses are causative agents of viral nervous necrosis (VNN), a devastating disease of cultured marine fish worldwide. Virus particles contain a single type of coat protein that spontaneously assembles into virus-like particles (VLPs) when expressed in a baculovirus expression system. In the present study, the immunogenicity of betanodavirus VLPs and the protection they confer against VNN in the European sea bass Dicentrarchus labrax were investigated. Enzyme-linked immunosorbent assay and seroneutralization tests performed on plasma from fish vaccinated intramuscularly with doses as low as 0.1 microg of VLPs indicated that the VLPs elicited the synthesis of specific antibetanodavirus antibodies with neutralizing activity. Moreover, fish vaccinated with VLPs were protected from challenge with live virus. Both the immune response and the protective effect against viral challenge were dose dependent. Reverse transcription-PCR data indicated that higher doses of vaccine also reduced the number of fish containing detectable quantities of betanodavirus RNA on day 30 after challenge. Taken together these data strongly support the hypothesis that VLPs obtained in the baculovirus expression system may represent an effective vaccine against VNN.