ABSTRACT
Zooglan, a weakly acidic exopolysaccharide produced by Zoogloea ramigera 115, catalyzed the preferential methanolysis of phospatidylcholine compared to other phospholipids when the reaction was carried out in pure methanol at 30 degrees C. The reaction was monitored by thin-layer chromatography (TLC) as well as (1)H and (31)P nuclear magnetic resonance (NMR) spectrometry. Zooglan enhanced the rate of methanolysis of dipalmitoylphosphatidylcholine (DPPC) up to about 170-fold compared to controls such as DPPC alone, pyruvic acid, succinic acid and acetic acid. Furthermore, the methanolysis was different depending on the head groups of the phospholipids. Through this study, we have shown that zooglan can act as an environmentally benign catalytic polysaccharide for methanolysis in pure methanol solution.
Subject(s)
Methanol/chemistry , Phospholipids/chemistry , Polysaccharides, Bacterial/chemistry , 1,2-Dipalmitoylphosphatidylcholine/chemistry , Catalysis , Hydrogen-Ion Concentration , Magnetic Resonance Spectroscopy , Zoogloea/chemistryABSTRACT
Two strains of free-living diazotrophs isolated from soil from a rice paddy field were characterized by using a polyphasic approach. The novel strains, A-7T and A-4, were found to be very closely related, with 99.9% 16S rRNA gene sequence similarity and a DNA-DNA hybridization value of 89.5%, suggesting that they represent a single species. 16S rRNA gene sequence analyses indicated that the two strains fell within the Zoogloea lineage, with less than 96.7 % sequence similarity to other Zoogloea species. Chemotaxonomic characteristics of the novel strains, including DNA G + C content (65.1 mol%), the major quinone system (Q-8), predominant fatty acids (16:1omega7c and 16:0) and major hydroxy fatty acids (3-OH 10:0 and 3-OH 12:0), are similar to those of the genus Zoogloea. The novel strains showed positive results for floc formation which is accepted as confirmatory for species of the genus Zoogloea. However, the novel strains can be distinguished from the other species of Zoogloea by physiological characteristics. The name Zoogloea oryzae sp. nov. is therefore proposed for the novel strains with strain A-7T (= IAM 15218T = CCTCC AB 2052005T) as the type strain. Phylogenetic and chemotaxonomic analyses indicate that strain ATCC 19623, designated as a reference strain of Zoogloea ramigera, does not belong to the genus Zoogloea but to a new genus of Alphaproteobacteria. The name Crabtreella saccharophila gen. nov., sp. nov. is proposed for strain ATCC 19623T (= IAM 12669T).
Subject(s)
Alphaproteobacteria/classification , Nitrogen Fixation , Oryza/microbiology , Soil Microbiology , Zoogloea/classification , Alphaproteobacteria/chemistry , Alphaproteobacteria/genetics , Alphaproteobacteria/isolation & purification , DNA, Ribosomal/chemistry , Fatty Acids/analysis , Phylogeny , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Zoogloea/chemistry , Zoogloea/genetics , Zoogloea/isolation & purificationABSTRACT
For preliminary screening for and characterization of free-living nitrogen-fixing bacteria from rhizoplane microflora, we used Winogradsky's mineral mixture-based nitrogen-free medium solidified with 0.3% gellan gum. The soft gel medium enabled some reference and wild free-living nitrogen-fixing bacteria to grow in characteristic colonies, including their reaction to oxygen and their motility change. Gellan gum is thus likely to be a better gel matrix than agarose for the investigation of root-associating, free-living nitrogen-fixing bacteria to identify their characteristic behaviors.
Subject(s)
Bacteria/isolation & purification , Nitrogen Fixation/physiology , Plant Roots/microbiology , Polysaccharides, Bacterial/chemistry , Bacteria/metabolism , Caulobacter/chemistry , Caulobacter/metabolism , Culture Media , Gels , Klebsiella pneumoniae/growth & development , Plantago/metabolism , Proteobacteria/metabolism , Sepharose , Zoogloea/chemistry , Zoogloea/metabolismABSTRACT
Nine Zoogloea strains including the type strain of Z. ramigera (IAM 12136 = ATCC 19544 = N.C. Dondero 106) and newly isolated strains were investigated for isoprenoid quinone composition and whole-cell fatty acid profiles. Seven of the tested strains, having phenotypic properties typical of Zoogloea, were characterized by their production of both ubiquinone-8 and rhodoquinone-8 as major quinones, whereas the remaining two strains, Z. ramigera IAM 12669 (= K. Crabtree I-16-M) and IAM 12670 (= P.R. Dugan 115), formed ubiquinone-10 and ubiquinone-8, respectively, as the sole quinone. All rhodoquinone-producing strains contained palmitoleic acid and 3-hydroxy-decanoic acid as the major components of nonpolar and hydroxylated fatty acids, respectively. Marked differences were noted in the fatty acid composition between the strains with and without rhodoquinones. The chemotaxonomic data suggested that the rhodoquinone-lacking strains should be excluded from the genus Zoogloea. Since there have been no reliable taxonomic tools for Zoogloea, rhodoquinone analysis may provide a new criterion of great promise for identifying Zoogloea strains.
