I-Cheng Tseng

Pelotomaculum terephthalicum sp. nov. and Pelotomaculum isophthalicum sp. nov : two anaerobic bacteria that degrade phthalate isomers in syntrophic association with hydrogenotrophic methanogens

An anaerobic phthalate isomer-degrading strain (JTT) that we previously isolated was characterized. In addition, a strictly anaerobic, mesophilic, syntrophic phthalate isomer-degrading bacterium, designated strain JIT, was isolated and characterized in this study. Both were non-motile rods that formed spores. In both strains, the optimal growth was observed at temperatures around 37°C and neutral pH. In syntrophic co-culture with the hydrogenotrophic methanogen Methanospirillum hungatei, both strains could utilize two or three phthalate isomers for growth, and produce acetate and methane as end products. Strain JTT was able to grow on isophthalate, terephthalate, and a number of low-molecular weight aromatic compounds, such as benzoate, hydroquinone, 2-hydroxybenzoate, 3-hydroxybenzoate, 2,5-dihydroxybenzoate, 3-phenylpropionate in co-culture with M. hungatei. It could also grow on crotonate, hydroquinone and 2,5-dihydroxybenzoate in pure culture. Strain JIT utilized all of the three phthalate isomers as well as benzoate and 3-hydroxybenzoate for growth in co-culture with M. hungatei. No substrates were, however, found to support the axenic growth of strain JIT. Neither strain JTT nor strain JIT could utilize sulfate, sulfite, thiosulfate, nitrate, fumarate, Fe (III) or 4-hydroxybenzoate as electron acceptor. Phylogenetically, strains JTT and JIT were relatively close to the members of the genera Pelotomaculum and Cryptanaerobacter in ‘Desulfotomaculum lineage I’. Physiological and chemotaxonomic characteristics indicated that the two isolates should be classified into the genus Pelotomaculum, creating two novel species for them. Here, we propose Pelotomaculum terephthalicum sp. nov. and Pelotomaculum isophthalicum sp. nov. for strain JTT and strain JIT, respectively. The type strains are strains JTT (= DSM 16121T = JCM 11824T = NBRC 100523T) and JIT (= JCM 12282T = BAA-1053T) for P. terephthalicum and P. isophthalicum, respectively.

Methanolinea Mesophila Sp. Nov., A Hydrogenotrophic Methanogen Isolated From Rice Field Soil, And Proposal Of The Archaeal Family Methanoregulaceae Fam. Nov. Within The Order Methanomicrobiales

A novel mesophilic, hydrogenotrophic methanogen, designated strain TNR(T), was isolated from an anaerobic, propionate-degradation enrichment culture that was originally established from a rice field soil sample from Taiwan. Cells were non-motile rods, 2.0-6.5 µm long by 0.3 µm wide. Filamentous (up to about 100 µm) and coccoid (about 1 µm in diameter) cells were also observed in cultures in the late exponential phase of growth. Strain TNR(T) grew at 20-40 °C (optimally at 37 °C), at pH 6.5-7.4 (optimally at pH 7.0) and in the presence of 0-25 g NaCl l(-1) (optimally at 0 g NaCl l(-1)). The strain utilized H(2)/CO(2) and formate for growth and produced methane. The G+C content of the genomic DNA was 56.4 mol%. Based on sequences of both the 16S rRNA gene and the methanogen-specific marker gene mcrA, strain TNR(T) was related most closely to Methanolinea tarda NOBI-1(T); levels of sequence similarities were 94.8 and 86.4 %, respectively. The 16S rRNA gene sequence similarity indicates that strain TNR(T) and M. tarda NOBI-1(T) represent different species within the same genus. This is supported by shared phenotypic properties, including substrate usage and cell morphology, and differences in growth temperature. Based on these genetic and phenotypic properties, strain TNR(T) is considered to represent a novel species of the genus Methanolinea, for which the name Methanolinea mesophila sp. nov. is proposed; the type strain is TNR(T) ( = NBRC 105659(T) = DSM 23604(T)). In addition, we also suggest family status for the E1/E2 group within the order Methanomicrobiales, for which the name Methanoregulaceae fam. nov. is proposed; the type genus of family is Methanoregula.

Cultivation of Methanogens under Low-Hydrogen Conditions by Using the Coculture Method

ABSTRACT We previously reported the isolation of novel methanogens by using a new cultivation method, referred to as the coculture method. Here, we extended our coculture method to various anaerobic environmental samples. As a result, we successfully cultivated some uncharacterized methanogens in coculture enrichments and eventually isolated a new methanogen, within the order Methanomicrobiales.

Microbial-ecological significance of sulfide precipitation within anaerobic granular sludge revealed by micro-electrodes study.

Micro-electrodes were applied to anaerobic granular sludge, which was developed in a UASB reactor, to examine intra-granule profiles with respect to pH, glucose and sulfide. When glucose was employed as a bulk liquid substrate, the micro-electrodes study demonstrated the pH behavior along granule depth: pH decrement at the granule exterior portion due to acid formation (buildup of acidity), and subsequent pH increment at the granule inner portion due to the consumption of acid (buildup of alkalinity). Sulfide micro-electrode proved sulfate reduction that mostly occurred at the granule exterior portion. Chemical equilibrium consideration evidently explained the occurrence of ferric sulfide predominantly in the interior portion, which accounts well for the morphology of a representative double-layered structure of granules grown on a low level of sulfite. Inorganic elements distribution within anaerobic granule was examined by electron probe X-ray micro analysis (EPMA) and ICP methods. The presence of crystalline calcium carbonate (calcite) was identified by X-ray diffraction analysis.

Treatment of Dilute Wastewater in a UASB Reactor at a Moderate Temperature : Microbiological Aspects

Abstract Changes in the activity and bacterial populations of various trophic groups and the morphology of the sludge over time were investigated in a UASB reactor treating dilute wastewater. The specific methanogenic activity on day 400 was 6.9 (0.30 kg CH 4 -COD/kg VSS/d), 2.5 (0.36), 0.83 (0.03) and 4.4 (0.19) times as large as the activities of the seed sludge when acetate, H 2 -CO 2 , propionate in the absence of sulfate, and propionate in the presence of sulfate were respectively used as test substrates. The viable cell numbers of trophic groups increased by 2 to 4 orders of magnitude for methanogens, 3 orders for acetogens, and 2 to 3 orders for sulfate-reducing bacteria as compared to the numbers of viable cells in the seed sludge. The anaerobic ciliate Metopus es incorporating methanogens was also observed.

Effect of Temperature Elevation from 55°C to 65°C on the Performance of a Thermophilic UASB Reactor and Characteristics of Methanogenic Granular Sludge

A thermophilic (55°C) upflow anaerobic sludge blanket (UASB) reactor was operated by feeding a wastewater containing sucrose at a fixed total organic carbon (TOC) loading rate of 18 kg TOC m−3 d−1 for a period of 3 years. After this operation period, the reactor temperature was shifted from 55°C to 65°C to investigate the effect of this temperature elevation both on reactor performance and on the characteristics of thermophilic granular sludge. A sharp increase in the effluent TOC occurred after the temperature shift, leading to a deterioration of TOC removal from 90% to 65%. Methane production from the reactor gradually increased from 100 to 130 l d−1 during the first 40 days of 65°C operation, and then drastically decreased to 40–50 l d−1. This process failure was attributed to the disintegration of the granular sludge during 65°C operation. Microbial characteristics of the granular sludge were evaluated before and after the temperature shift. The acetate-utilizing and propionate-utilizing methanogenic ...