University of Alicante

About: University of Alicante is a education organization based out in Alicante, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 8681 authors who have published 22690 publications receiving 476064 citations. The organization is also known as: Universitat d'Alacant & Universidad de Alicante.

Effects of Culture Conditions on Poly(β-Hydroxybutyric Acid) Production by Haloferax mediterranei

Abstract: The halobacterium Haloferax mediterranei accumulates poly(beta-hydroxybutyrate) (PHB) as intracellular granules. The conditions for PHB production in batch and continuous cultures have been studied and optimized. Phosphate limitation is essential for PHB accumulation in large quantities. Glucose and starch are the best carbon sources. With 2% starch, 0.00375% KH(2)PO(4), and 0.2% NH(4)Cl in batch culture, a production of ca. 6 g of PHB per liter was reached, being 60% of the total biomass dry weight, and giving a yield over the carbon source of 0.33 g/g. The PHB production in continuous cultures was stable over a 3-month period. Our results demonstrate that H. mediterranei is an interesting candidate for industrial production of biological polyesters.

Microbial Diversity in Maras Salterns, a Hypersaline Environment in the Peruvian Andes

Abstract: Maras salterns are located 3,380 m above sea level in the Peruvian Andes. These salterns consist of more than 3,000 little ponds which are not interconnected and act as crystallizers where salt precipitates. These ponds are fed by hypersaline spring water rich in sodium and chloride. The microbiota inhabiting these salterns was examined by fluorescence in situ hybridization (FISH), 16S rRNA gene clone library analysis, and cultivation techniques. The total counts per milliliter in the ponds were around 2 × 106 to 3 × 106 cells/ml, while the spring water contained less than 100 cells/ml and did not yield any detectable FISH signal. The microbiota inhabiting the ponds was dominated (80 to 86% of the total counts) by Archaea, while Bacteria accounted for 10 to 13% of the 4′,6′-diamidino-2-phenylindole (DAPI) counts. A total of 239 16S rRNA gene clones were analyzed (132 Archaea clones and 107 Bacteria clones). According to the clone libraries, the archaeal assemblage was dominated by microorganisms related to the cosmopolitan square archaeon “Haloquadra walsbyi,” although a substantial number of the sequences in the libraries (31% of the 16S rRNA gene archaeal clones) were related to Halobacterium sp., which is not normally found in clone libraries from solar salterns. All the bacterial clones were closely related to each other and to the γ-proteobacterium “Pseudomonas halophila” DSM 3050. FISH analysis with a probe specific for this bacterial assemblage revealed that it accounted for 69 to 76% of the total bacterial counts detected with a Bacteria-specific probe. When pond water was used to inoculate solid media containing 25% total salts, both extremely halophilic Archaea and Bacteria were isolated. Archaeal isolates were not related to the isolates in clone libraries, although several bacterial isolates were very closely related to the “P. halophila” cluster found in the libraries. As observed for other hypersaline environments, extremely halophilic bacteria that had ecological relevance seemed to be easier to culture than their archaeal counterparts.

Diversity of CRISPR loci in Escherichia coli.

Abstract: CRISPR (clustered regularly interspaced short palindromic repeats) and CAS (CRISPR-associated sequence) proteins are constituents of a novel genetic barrier that limits horizontal gene transfer in prokaryotes by means of an uncharacterized mechanism. The fundamental discovery of small RNAs as the guides of the defence apparatus arose as a result of Escherichia coli studies. However, a survey of the system diversity in this species in order to further contribute to the understanding of the CRISPR mode of action has not yet been performed. Here we describe two CRISPR/CAS systems found in E. coli, following the analysis of 100 strains representative of the species' diversity. Our results substantiate different levels of activity between loci of both CRISPR types, as well as different target preferences and CRISPR relevances for particular groups of strains. Interestingly, the data suggest that the degeneration of one CRISPR/CAS system in E. coli ancestors could have been brought about by self-interference.