Fecal IgA Levels Are Determined by Strain-Level Differences in Bacteroides ovatus and Are Modifiable by Gut Microbiota Manipulation

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Isoelectrophoretic characterization of extracellular polygalacturonases of variousAspergillus alliaceus strains

The composition of pectin hydrolase complexes produced by variousAspergillus alliaceus strains was studied under the conditions of induction, catabolite repression, or constitutive synthesis. The strains were found similar in terms of the polygalacturonase spectrum and different with regard to the levels of endo- and exoenzyme activities. The analysis of the zymograms of inducible polygalacturonases revealed that all tested cultures contained at least 24 molecular forms of polygalacturonase. Taking into account only the three molecular forms typical of all analyzed strains ofA. alliaceus with pI values of 5.7, 5.9, and 6.3, one can use the spectrum of constitutive, catabolite repression-resistant polygalacturonases as an additional taxonomic species criterion.     

Nucleotide sequence of the extracellular α-amylase gene in the yeast Schwanniomyces occidentalis ATCC 26077

The Schwanniomyces occidentalis (formerly castellii) ATCC 26077 (CBS 2863) alpha-amylase (AMY 26077) gene was cloned in Saccharomyces cerevisiae and sequenced. An open-reading frame encoding the AMY consists of 1536 base pairs and contains 512 amino-acid residues, which is almost the same in size as the AMY of Sch. occidentalis ATCC 26076 and CCRC 21164. The amino-acid sequence of AMY 26077 differed from that of ATCC 26076 alpha-amylase (AMY 26076) at two residues and from that of CCRC 21164 alpha-amylase (AMY 21164) at three residues. Comparison of the AMY 26077 gene with its homologues from two other strains (Sch. alluvius CBS 1153 and Sch. persoonii CBS 2169) using several restriction enzymes revealed that the AMY 26077 was very similar to AMY CBS 1153 but different from that of CBS 2169.     

Amino acid composition of azolla as affected by strains and population density

The total nitrogen and amino acid composition of seven Azolla strains were compared at four different growth phases. Total nitrogen content of the individual strains ranged from 2.6% to 5.7% of dry matter and was not significantly influenced by growth phase or population density. The concentration of the sixteen amino acids determined was maximal during the linear growth stage and specific differences occurred among Azolla strains. AnAzolla microphylla strain was the best source of amino acids and anA. filiculoides strain the poorest under the cultural conditions used. The chemical index score demonstrated the potential of some species, such as theA. microphylla strain, as contributor of protein for animals. Strains of other species, such asA. filiculoides, had several limiting amino acids and appear more suited for use solely as a green manure. All Azolla strains contained a similar proportion of essential (55%) and non-essential (45%) amino acids. Leucine, lysine, arginine and phenylanine+tyrosine were the predominant essential amino acids whereas the sulfur containing amino acids (methionine and cystine) were present in smaller amounts.     

Specific relations between some strains of diazotrophs and corn hybrids

Summary We tested the effect of a large number of diazotrophic strains from the genera Azotobacter, Klebsiella, Escherichia, Derxia, Beijerinckia, and Azospirillum, on nitrogen concentration in four corn hybrids. The range obtained, from highly significant positive to highly significant negative effects, indicates that the strains studied differed in their characters, including the capacity to form useful associations with certain hybrids. The forming of positive associations depended on the specificity of diazotrophic strains and corn hybrids.     

南方红豆杉产IAA内生芽胞杆菌的分离、鉴定及产脂肽类化合物研究

通过组织研磨法对南方红豆杉(Taxus wallichiana var. mairei)新鲜组织进行内生细菌的分离，利用16S rRNA测序技术对分离的内生细菌进行鉴定分析，使用高效液相色谱-高分辨飞行质谱测定菌液提取物IAA含量，利用HPLC-TOF-MS对提取物脂肽类化合物进行分离、鉴定，结合数据库筛选菌株产脂肽类化合物种类及含量差异。结果表明，从南方红豆杉根茎叶中共分离鉴定出内生细菌31株，筛选出产IAA菌株20株，其中编号为KLBMPTC10的芽胞杆菌属菌株产IAA含量高达210.3955 μg·L^-1。在对产IAA菌株所产脂肽类化合物的研究中发现，菌株KLBMPTC10是所有产IAA内生细菌中脂肽类化合物含量最丰富的，其产Iturin A2相对含量为26.06%，明显优于其他产IAA菌株。芽胞杆菌属菌株KLBMPTC10同时具备高产IAA和脂肽类化合物的能力，可作为研究菌株进一步开发。     

Occurrence of poly-d(−)-3-hydroxyalkanoates in the genus Bacillus

A range of Bacillus strains were examined for their ability to accumulate poly-D(-)-3-hydroxyalkanoates (poly-HAKs) which are naturally occurring materials that are optically active, biodegradable thermoplastics. The organisms could produce poly-D(-)-3-hydroxybutyrate (poly-HB) up to 50% of cell dry weight. The content of poly-HB in the cells varied with the growth conditions. The addition of propionate or valerate in the culture resulted in a synthesis of poly-D(-)-3-hydroxyvalerate (poly-HV). All the strains tested had the ability to synthesize the co-polyester poly-HB-co-HV.