ORIGINAL PAPER Characterization of polyhydroxyalkanoate and the phaC gene of Paracoccus seriniphilus E71 strain isolated from a polluted marine microbial mat Alejandro Lo ´pez-Corte ´s Æ Oliverio Rodrı ´guez-Ferna ´ndez Æ Hever Latisnere-Barraga ´n Æ Humberto C. Mejı ´a-Ruı ´z Æ Getzabeth Gonza ´lez-Gutie ´rrez Æ Carlos Lomelı ´-Ortega Received: 16 April 2009 / Accepted: 4 August 2009 / Published online: 21 August 2009 Ó Springer Science+Business Media B.V. 2009 Abstract Polyhydroxyalakanote (PHA) was produced by the marine bacteria Paracoccus seriniphilus Strain E71. Three methods were used for screening PHA in this strain: (1) microscopic analysis, (2) specifically designed primers for amplify fragments of phaC gene from Gram negative bacteria, and (3) measurements using spectroscopy, calo- rimetry, thermogravimetry, and rheology. The polyhydr- oxyalkanoic acid synthase gene (phaC) sequence had 77% identity with the phaC gene of P. denitrificans PD1222 strain. Additionally, the translated sequence showed an 86% similarity with the amino acid sequence of the phaC gene N-terminal portion of the P. denitrificans PD1222 strain. Our phaC sequence was closely related to two phaC sequences that correspond to P. denitrificans; therefore, this is the first report of a sequence of phaC that codifies a poly- (3-hydroxyalkanoate) synthase class I, specifically a poly- beta-hydroxybutyrate polymerase from the marine bacteria Paracoccus seriniphilus. The polymer PHA of E71 melts at 167.86°C(T m ), which corresponded to the fusion of the crystalline polymer and thermally degrades at 296.52°C, indicating that the biopolymer has good thermal stability. Rheology showed that this polymer behaves as a nonNew- tonian fluid. All these characteristics suggest that the E71 strain produces a PHA that corresponds to the crystalline thermoplastic polymer PHB type. Keywords Paracoccus seriniphilus Á E71 Á Polyhydroxyalkanoates Á phaC gene Á Microbial mats Á Physical properties Introduction Numerous bacteria accumulate polyhydroxyalkanoates (PHA), especially poly-ß-hydroxybutyrate (PHB). How- ever, very few of them can be used for industrial produc- tion purposes. As an industrial PHA production strain, the microorganism should satisfy the following requirements: rapid growth in cheap carbon sources, high PHA accu- mulation in the cells, high transformation efficiency of substrate in product, harmless to animals, humans, and the environment, large size to ease its separation, and easily lysed for PHA extraction (Chen 2002). Polymers of PHA show material properties that are similar to some common plastics, such as polypropylene (Suriyamongkol et al. 2007). The bacterial origin of PHA makes this polyester a natural material and indeed, many microorganisms have evolved the ability to degrade these macromolecules (Madison and Huisman 1999). The diversity of different monomers that can be incorporated into PHA, combined with a biological polymerization system that generates high molecular weight materials, has resulted in an enormous Electronic supplementary material The online version of this article (doi:10.1007/s11274-009-0149-5) contains supplementary material, which is available to authorized users. A. Lo ´pez-Corte ´s (&) Á G. Gonza ´lez-Gutie ´rrez Á C. Lomelı ´-Ortega Laboratorio de Ecologı ´a Microbiana Molecular, Centro de Investigaciones Biolo ´gicas del Noroeste (CIBNOR), Mar Bermejo 195, Colonia Playa Palo de Santa Rita, La Paz, BCS 23090, Mexico e-mail: alopez04@cibnor.mx O. Rodrı ´guez-Ferna ´ndez Centro de Investigaciones en Quı ´mica Aplicada (CIQA), Saltillo, Coahuila, Mexico H. Latisnere-Barraga ´n Á H. C. Mejı ´a-Ruı ´z Laboratorio de Biotecnologı ´a de Organismos Marinos, Centro de Investigaciones Biolo ´gicas del Noroeste (CIBNOR), La Paz, BCS, Mexico 123 World J Microbiol Biotechnol (2010) 26:109–118 DOI 10.1007/s11274-009-0149-5