Hideyuki Ohmori

Continuous hydrogen production from glucose by using extreme thermophilic anaerobic microflora.

Continuous hydrogen production from glucose at 75 degrees C was examined at HRTs of 0.67, 1, 2, and 3 d by using extreme thermophilic microflora, which consisted of several subspecies of Caldanaerobacter subterraneus. The maximum hydrogen yield of 3.32 mol-H2/mol-glucose degraded was obtained at the highest HRT, 3 d. Both the maximum volumetric and specific rates of hydrogen production (1.22 L-H2/L/d and 4.15 L-H2/g-VSS/d, respectively) were obtained at the lowest HRT, 0.67 d. A 16S rDNA analysis showed that the community structure of the microflora did not change at any of the HRTs.

Fermented liquid feed enhances bacterial diversity in piglet intestine

Because of limitations imposed on the antibiotic use in animal industry, there is a need for alternatives to maintain the efficiency of production. One of them may be the use of fermented liquid feed (FLF) but how it affects gut ecology is poorly understood. We investigated the effect of three diets, standard dry feed (control), dry feed supplemented with antibiotics, and fermented liquid feed (FLF, fermented with Lactobacillus plantarum), on gut bacterial diversity in piglets. The structure of the ileal and caecal communities was estimated by sequencing the SSU rRNA gene libraries. Antibiotic-supplemented feed slightly increased bacterial diversity in the ileum but reduced it in the caecum while in FLF-fed animals bacterial diversity was elevated. The majority of bacterial sequences in the ileum of all three groups belonged to lactobacilli (92-98%). In the caecum the lactobacilli were still dominant in control and antibiotic-fed animals (59% and 64% of total bacterial sequences, respectively) but in FLF-fed animals they fell to 31% with the concomitant increase in the Firmicutes diversity represented by the Dorea, Coprococcus, Roseburia and Faecalibacterium genera. Thus FLF affects the gut ecology in a different way than antibiotics and contributes to the enhanced bacterial diversity in the gastrointestinal tract.

Life cycle assessment of animal feeds prepared from liquid food residues: a case study of rice-washing water.

Life cycle assessment (LCA) was used to compare the greenhouse gas (GHG) emissions and energy consumption of three methods used to produce animal feed from concentrated rice-washing water (CRW) and disposing of the rice-washing water through wastewater treatment. Four scenarios were compared using LCA: (i) producing concentrated liquid feed by centrifugation (CC) of CRW with wastewater treatment and discharge of the supernatant, (ii) producing concentrated liquid feed by heating evaporation (HC) of CRW, (iii) producing dehydrated feed by dehydration (DH) of CRW, and (iv) wastewater treatment and discharge of nonconcentrated rice-washing water (WT). The functional unit (FU) was defined as 1 metric ton of rice washed for cooking or processing. Our results suggested that the energy consumptions of CC, HC, DH, and WT were 108, 322, 739, and 242 MJ per FU, respectively, and the amounts of GHG emissions from CC, HC, DH, and WT were 6.4, 15.8, 45.5, and 22.5 kg of CO equivalents per FU, respectively. When the produced feed prepared from CRW was assumed to be transported 200 km to farms, CC and HC still emitted smaller GHGs than the other scenarios, and CC consumed the smallest amount of energy among the scenarios. The present study indicates that liquid feed production from CRW by centrifugation has a remarkably reduced environmental impact compared with the wastewater treatment and discharge of rice-washing water.

Reduction of chlortetracycline-resistant Escherichia coli in weaned piglets fed fermented liquid feed

We investigated the change in chlortetracycline resistance in 360 Escherichia coli strains separated from the feces of piglets fed fermented liquid feed (FLF) in comparison with those fed dry feed (control). The total amount of lactic acid bacteria in feces was 8.77 x 10(8) CFU/g DM at weaning, which increased to 1.23 x 10(12) CFU/g DM (FLF) at 28 days after weaning (P<0.001). As a result of the antibiotic susceptibility test, almost all isolates were chlortetracycline-resistant (CTCR) until 14 days after weaning both in the FLF and control groups. At 28 days, the CTCR E. coli decreased to 22.2% in the FLF group, while the proportion of resistant bacteria was 88.9% in the control group. In addition, as a result of the gene analysis, it was clarified that there is a relation between the decrease in the minimum inhibitory concentration values and the possession rate of the tetracycline-resistance gene tet(A), tet(B) and tet(D). These results show that FLF caused an increase in the number of lactic acid bacteria in the intestines, and suggested that the feeding of FLF can possibly reduce antibiotic-resistance bacteria.

Extracellular Secretion of Noncatalytic Plant Cell Wall-Binding Proteins by the Cellulolytic Thermophile Caldicellulosiruptor bescii

Caldicellulosiruptor bescii efficiently degrades cellulose, xylan, and native grasses at high temperatures above 70°C under anaerobic conditions. C. bescii extracellularly secretes multidomain glycoside hydrolases along with proteins of unknown function. In this study, we analyzed the C. bescii proteins that bind to the cell walls of timothy grass by using mass spectrometry, and we identified four noncatalytic plant cell wall-binding proteins (PWBPs) with high pI values (9.2 to 9.6). A search of a conserved domain database showed that these proteins possess a common domain related to solute-binding proteins. In addition, 12 genes encoding PWBP-like proteins were detected in the C. bescii genomic sequence. To analyze the binding properties of PWBPs, recombinant PWBP57 and PWBP65, expressed in Escherichia coli, were prepared. The PWBPs displayed a wide range of binding specificities: they bound to cellulose, lichenan, xylan, arabinoxylan, glucuronoxylan, mannan, glucomannan, pectin, oligosaccharides, and the cell walls of timothy grass. The proteins showed the highest binding affinity for the plant cell wall, with association constant (Ka) values of 5.2 × 10(6) to 44 × 10(6) M(-1) among the insoluble polysaccharides tested, as measured using depletion binding isotherms. Affinity gel electrophoresis demonstrated that the proteins bound to the acidic polymer pectin most strongly among the soluble polysaccharides tested. Fluorescence microscopic analysis showed that the proteins bound preferentially to the cell wall in a section of grass leaf. Binding of noncatalytic PWBPs with high pI values might be necessary for efficient utilization of polysaccharides by C. bescii at high temperatures.

Brewer's yeast efficiently degrades phytate phosphorus in a corn‐soybean meal diet during soaking treatment

Microbes such as yeast and Aspergillus are known to produce phytase, and Aspergillus phytase has been used as a feed additive for improving phytate-phosphorus bioavailability in monogastric animals. We measured phytase activity in some by-products from fermented food and beverage productions by yeast and Aspergillus. The phytase activity was as high as 3577 and 2225 PU/kg DM in raw and dried brewers yeasts, respectively. On the other hand, the phytase activity was approximately 400 PU/kg DM in white-wine yeast and red-wine yeast. The phytase activity was further low in natto (fermented soybean) residue, soy sauce cake, rice brewers grain and the activity was not detected in dried corn-barley distillers grain with soluble and sweet-potato distillers residue. The stability of phytase against pepsin was much lower in the brewers yeast than in an Aspergillus phytase preparation. On the other hand, the addition of raw brewers yeast effectively degraded phytate phosphorus in a corn-soybean meal diet during soaking. These results suggest that phytase in the examined by-products is not suitable for the phytase source of conventional diets, but that the soaking treatment with a raw brewers yeast is an alternative method for improving phytate-phosphorus bioavailability in corn-soybean meal diets for pigs.

Lactobacillus mixtipabuli sp. nov. isolated from total mixed ration silage.

Using a polyphasic taxonomic approach, we investigated three bacterial strains - IWT30T, IWT8 and IWT75 - isolated from total mixed ration silage prepared in Hachimantai, Iwate, Japan. The isolates comprised Gram-stain positive, non-motile, non-spore-forming, catalase-negative, rod-shaped bacteria. Good growth occurred at 15-45 °C and at pH 4.0-7.5. Their major cellular fatty acids were C18:1ω9c and C19:1 cyclo 9,10.The G+C content of genomic DNA of strain IWT30T was 44.6 mol%. Comparative 16S rRNA gene sequence analysis showed that these novel strains belonged to the genus Lactobacillus. These strains shared 100 % 16S rRNA gene sequence similarity and were most closely related to the type strains of Lactobacillus silagei, Lactobacillus odoratitofui, Lactobacillus similis, Lactobacillus collinoides, Lactobacillus paracollinoides and Lactobacillus kimchicus, with sequence similarity values of 99.5, 98.8, 98.7, 97.8, 97.8 and 96.8 %, respectively. The level of DNA-DNA relatedness between these strains and their closest phylogenetic neighbours was less than 30 %. On the basis of additional phylogenetic analysis of pheS and rpoA gene sequences and phenotypic and chemotaxonomic characteristics, we conclude that these three strains represent a novel species of the genus Lactobacillus, for which we propose the name Lactobacillus mixtipabuli sp. nov. The type strain is IWT30T ( = JCM 19805T = DSM 28580T).

Segmented filamentous bacteria are a major group in terminal ileum of piglets

Metabolically active microbiota of the porcine terminal ileum mucosa was analyzed by RT-PCR of 16S rRNAs. The majority of 1951 sequences retrieved (24.8%) displayed the closest similarity to segmented filamentous bacteria (SFB). Phylogenetic analysis inferred the host-specific clusters of SFB sequences suggesting the host-specific selection of this group of bacteria.

Diauxic growth of Fibrobacter succinogenes S85 on cellobiose and lactose

ABSTRACT Fibrobacter succinogenes rapidly colonizes the preruminant calf rumen and becomes a dominant cellulolytic bacterium in the rumen after weaning. Although F. succinogenes actively degrades cellulose in the rumen, it seems that there is no or little of its substrate, cellulose, in the rumen of preweaned calves. We thus evaluated the ability of F. succinogenes to utilize lactose, a main sugar of milk, with or without the presence of cellobiose. We grew F. succinogenes S85 on media containing 2.5% lactose combined with 0%‐0.2% cellobiose or a medium with 0.2% cellobiose but without lactose. The generation times on the 0.2% cellobiose medium and the 2.5% lactose medium were 1.9 and 16.2 h, respectively. The bacterium showed rapid growth on cellobiose and diauxic growth on the lactose media containing 0.05%‐0.2% cellobiose. Moreover, the production of &bgr;‐galactosidase was low in the presence of 0.1%‐0.2% cellobiose. Since the &bgr;‐galactosidase contained a signal peptide and a Por secretion system C‐terminal sorting domain, we speculate that the &bgr;‐galactosidase would be secreted from the bacterial cells by the Por secretion system. Our data indicate the possibility that F. succinogenes could colonize preruminant calf rumen, consuming the lactose present in cow milk.

An improved dry ash procedure for the detection of titanium dioxide in cattle feces.

We improved the dry ash procedure for detecting titanium dioxide (TiO2 ) in cattle feces containing chromium oxide [corrected] (Cr(2)O(3) ). First, the effect of amount of sodium sulfate (Na2 SO4 ) on the recovery of TiO2 from cattle feces that contained Cr2 O3 was evaluated. Average recovery of TiO2 at the 2.5 g Na2 SO4 level was significantly higher (P < 0.0001) than that at 0.75 g Na2 SO4 . Second, the effect of Cr2 O3 concentration on the recovery of TiO2 of cattle feces by using two levels of Na2 SO4 addition was examined. The recovery of TiO2 decreased with the increase in the amount of Cr2 O3 at the 0.75 g Na2 SO4 level but was consistently high at 2.5 g Na2 SO4 . Third, the recovery of Cr2 O3 from cattle feces was checked. The recoveries of TiO2 and Cr2 O3 were high enough at the 2.5 g Na2 SO4 level. Fourth, the improved dry ash procedure (5 mL of concentrated H2 SO4 and 2.5 g of Na2 SO4 were used for sample digestion) was compared to the wet ash procedure. Average recovery of TiO2 by the improved dry ash procedure was significantly higher (P = 0.0077) than that by the wet ash procedure. Thus, the improved dry ash procedure can be used for TiO2 analysis in cattle feces containing Cr2 O3 .