Norio Kurosawa

Maximum organic loading rate for the single-stage wet anaerobic digestion of food waste.

Anaerobic digestion of food waste was conducted at high OLR from 3.7 to 12.9 kg-VS m(-3) day(-1) for 225 days. Periods without organic loading were arranged between the each loading period. Stable operation at an OLR of 9.2 kg-VS (15.0 kg-COD) m(-3) day(-1) was achieved with a high VS reduction (91.8%) and high methane yield (455 mL g-VS-1). The cell density increased in the periods without organic loading, and reached to 10.9×10(10) cells mL(-1) on day 187, which was around 15 times higher than that of the seed sludge. There was a significant correlation between OLR and saturated TSS in the sludge (y=17.3e(0.1679×), r(2)=0.996, P<0.05). A theoretical maximum OLR of 10.5 kg-VS (17.0 kg-COD) m(-3) day(-1) was obtained for mesophilic single-stage wet anaerobic digestion that is able to maintain a stable operation with high methane yield and VS reduction.

Sulfurisphaera ohwakuensis gen. nov., sp. nov., a novel extremely thermophilic acidophile of the order Sulfolobales

Three spherical thermoacidophilic archaea (strains TA-1T, TA-13, TA-14) were obtained from acidic hot springs located in Ohwaku Valley, Hakone, Japan. All the isolates are facultatively anaerobic, and grew optimally at around 85 degrees C, pH 2.0. Isolate TA-1T was characterized further. The G + C content of DNA from TA-1T is 33 mol%. Although these properties resemble those of the genus Acidianus, the sequence of the 16S rRNA gene from strain TA-1T was more similar to that of species of Stygiolobus than of Acidianus. DNA-DNA hybridization experiments also indicated that strain TA-1T is clearly distinguished phylogenetically from the members of Acidianus, Sulfolobus and Metallosphaera. On the basis of the distinct physiological and molecular properties, we describe the new strains as members of the new genus Sulfurisphaera. The type species of the genus is Sulfurisphaera ohwakuensis, and the type strain of the species is TA-1T (= IFO 15161T).

The structure of the core polyol of the ether lipids fromSulfolobus acidocaldarius

The major ether-type lipid structures ofSulfolobus acidocaldarius (ATCC33909) were composed of caldarchaeol and calditoglycerocaldarchaeol. However, the characterization by nuclear magnetic resonance spectroscopy and mass spectrometry showed that the structure of calditol in calditoglycerocaldarchaeol is not nonitol, 2-(1′,2′,3′-trihydroxypropyl)1,2,3,4,5,6-hexahydroxyhexane, but 2-hydroxymethyl-1-(2,3-dihydroxypropoxy),2,3,4,5-cyclopentanetetraol with an ether linkage in the molecule. Such an intermolecular ether linkage was resistant, to BCl3 treatment, but nonresistant to 57% HI degradation treatment conducted at 100°C for 60 h, producting 2-hydroxymethyl-1,2,3,4,5-cyclopentanepentaol from calditol as reaction product. Further, it was confirmed that the structure of calditol is essentially a derivative of glycerol, and hydrocarbon chains were conjugated to the glycerol-like site in the structure. The calditol with an ether linkage in the molecule suggested an important role regarding the properties of heat-resistance and acid-resistance observed inSulfolobales.

Molecular cloning and characterization of avian N-methyl-D-aspartate receptor type1 (NMDA-R1) gene

Birds have several advantages in the study of memory formation, as imprinting and passive avoidance behaviors in chick are often used as model systems. However, the primary structure of the bird N-methyl-d-aspartate (NMDA) responsive glutamate receptor, which is assumed to play a critical role in memory formation, has not been determined. In this report we describe the cDNA cloning of a subunit of NMDA receptors (NMDA-R1) from duck and analysis of its structure and distribution in the brain. The N-terminal 898 amino acids of the NMDA-R1 were well conserved between duck and mammals, but the homology was completely lost in the C-terminus. In situ hybridization showed that the duck NMDA-R1 gene was expressed throughout the brain as it is in mammals.

Redox-dependent structural changes in archaeal and bacterial Rieske-type [2Fe-2S] clusters.

Proteins containing Rieske‐type [2Fe‐2S] clusters play important roles in many biological electron transfer reactions. Typically, [2Fe‐2S] clusters are not directly involved in the catalytic transformation of substrate, but rather supply electrons to the active site. We report herein X‐ray absorption spectroscopic (XAS) data that directly demonstrate an average increase in the iron–histidine bond length of at least 0.1 Å upon reduction of two distantly related Rieske‐type clusters in archaeal Rieske ferredoxin from Sulfolobus solfataricus strain P‐1 and bacterial anthranilate dioxygenases from Acinetobacter sp. strain ADP1. This localized redox‐dependent structural change may fine tune the protein–protein interaction (in the case of ARF) or the interdomain interaction (in AntDO) to facilitate rapid electron transfer between a lower potential Rieske‐type cluster and its redox partners, thereby regulating overall oxygenase reactions in the cells.

Paenibacillus thermoaerophilus sp. nov., a moderately thermophilic bacterium isolated from compost.

A rod-shaped, endospore-forming, Gram-reaction-positive bacterium, designated strain TC22-2b(T), was isolated from compost in Tochigi, Japan. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain belonged to a cluster comprising species of the genus Paenibacillus and was most closely related to the type strain of Paenibacillus elgii (93.4% similarity). The major cellular fatty acids were C(16:0) (25.5%), iso-C(16:0) (23.6%) and anteiso-C(15:0) (21.5%). The predominant menaquinone was MK-7. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The diamino acid found in the cell wall peptidoglycan was meso-diaminopimelic acid, and the DNA G+C content was 59.1 mol%. The results of physiological and biochemical tests enabled the phenotypic differentiation of strain TC22-2b(T) from the most closely related species with validly published names. Phylogenetic and phenotypic evidence reveals that strain TC22-2b(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus thermoaerophilus sp. nov. is proposed. The type strain of the novel species is TC22-2b(T) ( =DSM 26310(T)  =JCM 18657(T)).

Changes in Bacterial Communities Accompanied by Aggregation in a Fed-Batch Composting Reactor

The contents of fed-batch composting (FBC) reactors often aggregate after prolonged operation. This process leads to irreversible breakdown of the decomposition reaction and possible alteration of the bacterial communities. We compared the structures of bacterial communities in reactors under aggregate and optimal conditions. The results of 16S rRNA gene clone analysis showed that populations of the family Bacillaceae (such as Bacillus spp., Cerasibacillus spp., Gracilibacillus spp.), which dominate (98%) under optimal condition, were significantly decreased under aggregate condition. In contrast, populations of the family Staphylococcaceae considerably increased after aggregation and accounted for 53% of the total. Phylogenetic analysis also showed that anaerobes or facultative anaerobes related to Tetragenococcus halophilus, Atopostipes suicloacalis, Jeotgalicoccus pinnipedialis, and Staphylococcus spp. were dominant in the aggregates. These results suggested that aerobic Gram-positive bacteria mainly contributed to organic degradation and that aggregation created some anaerobic environment, which promoted the growth of bacterial communities usually not found in well-functioning FBC reactors.

Phylogenetic analysis of archaeal PCNA homologues.

Abstract Proliferating cell nuclear antigen (PCNA) is an essential component of the DNA replication and repair machinery in the domain Eucarya. Eukaryotes and euryarchaeotes, which belong to one subdomain of Archaea, possess a single PCNA homologue, whereas two distinct PCNA homologues have been identified from Sulfolobus solfataricus, which belongs to the other archaeal subdomain, Crenarchaeota. We have cloned and sequenced two genes of PCNA homologues from the thermoacidophilic crenarchaeon Sulfurisphaera ohwakuensis. These genes, referred to as the Soh PCNA A gene and the Soh PCNA B gene, were found to encode 245 amino acids (aa) (27 kDa) and 248 aa (27 kDa), respectively. In deduced amino acid sequences of both PCNA homologues, the motif L/I-A-P-K/R, implicated in binding of PCNA with replication factor C (RFC), was identified. Phylogenetic analysis of all available archaeal PCNA homologues suggests that crenarchaeal homologues are divided into two groups. Group A consists of Soh PCNA A, one of the S. solfataricus PCNA homologues, and one of the Aeropyrum pernix PCNA homologues. The other crenarchaeal homologues form group B. Crenarchaeal PCNA homologues constitute a monophyletic subfamily. These results suggest that the evolution of crenarchaeal PCNA homologues has been characterized by one or two gene duplication events, which are assumed to have occurred after the split of the crenarchaeal and euryarchaeal lineages.

Molecular cloning of the kainate-binding protein and calmodulin genes which are induced by an imprinting stimulus in ducklings

For the formation of imprinting in birds, protein synthesis is known to be essential in the medial hyperstriatum ventrale (MHV) of the forebrain after presentation of an imprinting stimulus. We have searched for the genes whose expressions are increased in ducklings MHV during formation of imprinting, and identified kainate-binding protein and calmodulin genes. This may reflect the formation of glutamatergic pathways in MHV.

Archaeal Community Structures in the Solfataric Acidic Hot Springs with Different Temperatures and Elemental Compositions

Archaeal 16S rRNA gene compositions and environmental factors of four distinct solfataric acidic hot springs in Kirishima, Japan were compared. The four ponds were selected by differences of temperature and total dissolved elemental concentration as follows: (1) Pond-A: 93°C and 1679 mg L−1, (2) Pond-B: 66°C and 2248 mg L−1, (3) Pond-C: 88°C and 198 mg L−1, and (4) Pond-D: 67°C and 340 mg L−1. In total, 431 clones of 16S rRNA gene were classified into 26 phylotypes. In Pond-B, the archaeal diversity was the highest among the four, and the members of the order Sulfolobales were dominant. The Pond-D also showed relatively high diversity, and the most frequent group was uncultured thermoacidic spring clone group. In contrast to Pond-B and Pond-D, much less diverse archaeal clones were detected in Pond-A and Pond-C showing higher temperatures. However, dominant groups in these ponds were also different from each other. The members of the order Sulfolobales shared 89% of total clones in Pond-A, and the uncultured crenarchaeal groups shared 99% of total Pond-C clones. Therefore, species compositions and biodiversity were clearly different among the ponds showing different temperatures and dissolved elemental concentrations.