Optimization of anaerobic co-digestion of strawberry and fish waste.

Anaerobic co-digestion of agri-food waste is a promising management alternative. Its implementation, however, requires evaluating the proportion in which waste should be mixed to optimize their centralized treatment. The combined treatment of strawberry extrudate and fish waste, which are widely generated in Mediterranean areas, was optimized. Strawberry extrudate and fish waste were mixed and treated at different proportions (88:12, 94:6, and 97:3, respectively; wet basis). The proportions selected for the mixture allow the different flows to be absorbed simultaneously. The highest methane production was observed for the ratio 94:6 (0.205 m(3) STP CH4/kg volatile solid) (VS) (STP; 0 °C, 1 atm), with a methane production rate in the range of 5 · 10(-3)-9 · 10(-3) m(3) STP/kg VS · d, while the highest organic loading rate was observed for the mixture at a proportion 88:12 (1.9 ± 0.1 kg VS/m(3) · d). Biodegradability was found to be similar for the 88:12 and 94:6 proportions, with values around 90 % in VS. Nevertheless, the 97:3 ratio was not viable due to a low methane production. An inhibition phenomenon occurred at increasing loads due to the effect of some compounds contained in the fish waste such as chloride or nitrogen.

Haloferax sulfurifontis sp. nov., a halophilic archaeon isolated from a sulfide- and sulfur-rich spring.

A pleomorphic, extremely halophilic archaeon (strain M6(T)) was isolated from a sulfide- and sulfur-rich spring in south-western Oklahoma (USA). It formed small (0.8-1.0 mm), salmon pink, elevated colonies on agar medium. The strain grew in a wide range of NaCl concentrations (6 % to saturation) and required at least 1 mM Mg(2+) for growth. Strain M6(T) was able to reduce sulfur to sulfide anaerobically. 16S rRNA gene sequence analysis indicated that strain M6(T) belongs to the family Halobacteriaceae, genus Haloferax; it showed 96.7-98.0 % similarity to other members of the genus with validly published names and 89 % similarity to Halogeometricum borinquense, its closest relative outside the genus Haloferax. Polar lipid analysis and DNA G+C content further supported placement of strain M6(T) in the genus Haloferax. DNA-DNA hybridization values, as well as biochemical and physiological characterization, allowed strain M6(T) to be differentiated from other members of the genus Haloferax. A novel species, Haloferax sulfurifontis sp. nov., is therefore proposed to accommodate the strain. The type strain is M6(T) (=JCM 12327(T)=CCM 7217(T)=DSM 16227(T)=CIP 108334(T)).

Taxonomic study of Halorubrum distributum and proposal of Halorubrum terrestre sp. nov.

Halorubrum distributum (basonym, Halobacterium distributum) is an extremely halophilic, aerobic archaeon isolated from saline soils, which was described on the basis of phenotypic features of several strains. The designated type strain of the species (1m(T)=VKM B-1733(T)=JCM 9100(T)) was shown recently to differ from the other strains. In this study, Halorubrum distributum isolates have been characterized with regard to phenotypic features, polar lipid content, comparison of 16S rRNA gene sequences and DNA-DNA hybridization. On the basis of these data, a novel species that includes the other isolates is proposed, with the name Halorubrum terrestre sp. nov. The type strain of this novel species is 4p(T) (=VKM B-1739(T)=JCM 10247(T)). The DNA G+C content of this novel species is 64.2-64.9 mol% (64.4 mol% for the type strain).

Isolation of Halobacterium salinarum retrieved directly from halite brine inclusions.

Halite crystals were selected from a 186 m subsurface core taken from the Badwater salt pan, Death Valley, California to ascertain if halophilic Archaea and their associated 16S rDNA can survive over several tens of thousands of years. Using a combined microscope microdrill/micropipette system, fluids from brine inclusions were aseptically extracted from primary, hopper texture, halite crystals from 8 and 85 metres below the surface (mbls). U-Th disequilibrium dating indicates that these halite layers were deposited at 9,600 and 97,000 years before present (ybp) respectively. Extracted inclusions were used for polymerase chain reaction (PCR) analysis with haloarchaea-specific 16S rDNA primers or placed into haloarchaea culture medium. Enrichment cultures were obtained from 97 kyr halite crystal inclusion fluid and haloarchaea-containing prepared crystals (positive controls), whereas inclusions from crystals of 9.6 kyr halite and the haloarchaea-free halite crystals (negative controls) resulted in no growth. Phylogenetic analysis (16S rDNA) of the 97 kyr isolate, designated BBH 001, revealed a homology of 100% with Halobacterium salinarum. DNA-DNA hybridization experiments confirmed that BBH 001 was closely related to H. salinarum (81-75% hybridization) and its ascription to this haloarchaea species. The described method of retrieving particle-containing brine from fluid inclusions offers a robust approach for assessing the antiquity of microorganisms associated with evaporites.

Taxonomic characterization of Haloferax sp. (" H. alicantei") strain Aa 2.2: description of Haloferax lucentensis sp. nov.

An extremely halophilic archaeon, previously named as Haloferax sp. strain Aa 2.2 or "Haloferax alicantei" that has been extensively used for genetic studies with halobacteria, was taxonomically characterized by using phenotypic tests (including morphological, physiological, biochemical and nutritional features), DNA-DNA hybridization and 16S rRNA sequence phylogenetic analysis. This organism was isolated in 1986 by Torreblanca et al. from a pond of a Spanish saltern located in Alicante. The cells were pleomorphic, Gram negative and grew optimally at 25% NaCl. The polar lipid composition was similar to that of species of the genus Haloferax. The DNA G+C content of this strain was 64.5 mol%. Phylogenetic analysis based on 16S rRNA sequence comparison confirmed that this archaeon is a member of the genus Haloferax and was most closely related to Haloferax volcanii. DNA-DNA hybridization between strain Aa 2.2 and the type strain of all named species of the genus Haloferax revealed low levels of relatedness (25-2%), supporting the placement of this organism in a new species. On the basis of the phenotypic characteristics, molecular data and phylogenetic analysis we propose to name strain Aa 2.2 as a new species, Haloferax lucentensis sp. nov. The type strain is Aa 2.2 (=JCM 9276=NCIMB 13854=CIP 107410=DSM 14919=CECT 5871=CCM 7023).