Phenotypic properties of <Emphasis Type="Italic">Sulfobacillus thermotolerans</Emphasis>: Comparative aspects

The phenotypic characteristics of the species Sulfobacillus thermotolerans Kr1^T, as dependent on the cultivation conditions, are described in detail. High growth rates (0.22–0.30 h^?1) and high oxidative activity were recorded under optimum mixotrophic conditions at 40 °C on medium with inorganic (Fe(II), S⁰, or pyrite-arsenopyrite concentrate) and organic (glucose and/or yeast extract) substrates. In cells grown under optimum conditions on medium with iron, hemes a, b, and, most probably, c were present, indicating the presence of the corresponding cytochromes. Peculiar extended structures in the form of cylindrical cords, never observed previously, were revealed; a mucous matrix, likely of polysaccharide nature, occurred around the cells. In the cells of sulfobacilli grown litho-, organo-, and mixotrophically at 40 °C, the enzymes of the three main pathways of carbon utilization and some enzymes of the TCA cycle were revealed. The enzyme activity was maximum under mixotrophic growth conditions. The growth rate in the regions of limiting temperatures (55 °C and 12–14 °C) decreased two-and tenfold, respectively; no activity of 6-phosphogluconate dehydrogenase, one of the key enzymes of the oxidative pentose phosphate pathway, could be revealed; and a decrease in the activity of almost all enzymes of glucose metabolism and of the TCA cycle was observed. The rate of ¹⁴CO₂ fixation by cells under auto-, mixo-, and heterotrophic conditions constituted 31.8, 23.3, and 10.3 nmol/(h mg protein), respectively. The activities of RuBP carboxylase (it peaked during lithotrophic growth) and of carboxylases of heterotrophic carbon dioxide fixation were recorded. The physiological and biochemical peculiarities of the thermotolerant bacillus are compared versus moderately thermophilic sulfobacilli.     

<Emphasis Type="Italic">Zunongwangia flava</Emphasis> sp. nov., belonging to the family <Emphasis Type="Italic">Flavobacteriaceae</Emphasis>, isolated from <Emphasis Type="Italic">Salicornia europaea</Emphasis>

A yellow pigmented bacterium designated strain MBLN094^T within the family Flavobacteriaceae was isolated from a halophyte Salicornia europaea on the coast of the Yellow Sea. This strain was a Gram-stain negative, aerobic, non-spore forming, rod-shaped bacterium. Phylogenetic analysis of the 16S rRNA gene sequence of strain MBLN094^T was found to be related to the genus Zunongwangia, exhibiting 16S rRNA gene sequence similarity values of 97.0, 96.8, 96.4, and 96.3% to Zunongwangia mangrovi P2E16^T, Z. profunda SM-A87^T, Z. atlantica 22II14-10F7^T, and Z. endophytica CPA58^T, respectively. Strain MBLN094^T grew at 20?37°C (optimum, 25?30°C), at pH 6.0?10.0 (optimum, 7.0?8.0), and with 0.5?15.0% (w/v) NaCl (optimum, 2.0?5.0%). Menaquinone MK-6 was the sole respiratory quinone. The polar lipids were phosphatidylethanolamine, two unidentified aminolipids, and four unidentified lipids. Major fatty acids were iso-C_17:0 3-OH, summed feature 3 (C_16:1ω6c and/or C16:1 ω7c), and iso-C_15:0. The genomic DNA G + C content was 37.4 mol%. Based on these polyphasic taxonomic data, strain MBLN094^T is considered to represent a novel species of the genus Zunongwangia, for which the name Zunongwangia flava sp. nov. is proposed. The type strain is MBLN094^T (= KCTC 62279^T = JCM 32262^T).     

<Emphasis Type="Italic">Nibribacter flagellatus</Emphasis> sp. nov., isolated from rhizosphere of <Emphasis Type="Italic">Hibiscus syriacus</Emphasis> and emended description of the genus <Emphasis Type="Italic">Nibribacter</Emphasis>

A Gram-stain negative, aerobic, motile by flagella, rod-shaped strain (THG-T16^T) was isolated from rhizosphere of Hibiscus syriacus. Growth occurred at 10–40 °C (optimum 28–30 °C), at pH 6.0–8.0 (optimum 7.0) and at 0–1.0% NaCl (optimum 0%). Based on 16S rRNA gene sequence analysis, the near phylogenetic neighbours of strain THG-T16^T were identified as Nibribacter koreensis KACC 16450^T (98.6%), Rufibacter roseus KCTC 42217^T (94.7%), Rufibacter immobilis CCTCC AB 2013351^T (94.5%) and Rufibacter tibetensis CCTCC AB 208084^T (94.4%). The DNA G+C content of strain THG-T16^T was determined to be 46.7 mol%. DNA–DNA hybridization values between strain THG-T16^T and N. koreensis KACC 16450^T, R. roseus KCTC 42217^T, R. immobilis CCTCC AB 2013351^T, R.tibetensis CCTCC AB 208084^T were 33.5?±?0.5% (31.7?±?0.7% reciprocal analysis), 28.1?±?0.2% (25.2?±?0.2%), 17.1?±?0.9% (10.2?±?0.6%) and 8.1?±?0.3% (5.2?±?0.1%). The polar lipids were identified as phosphatidylethanolamine, two unidentified aminophospholipids, an unidentified aminolipid and three unidentified lipids. The quinone was identified as MK-7 and the polyamine as sym-homospermidine. The major fatty acids were identified as C_16:1 ω5c, C_17:1 ω6c, iso-C_15:0, summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c) and summed feature 4 (iso-C_17:1 I and/or anteiso-C_17:1 B). On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics, and DNA–DNA hybridization data, strain THG-T16^T represents a novel species of the genus Nibribacter, for which the name Nibribacter flagellatus sp. nov. is proposed. The type strain is THG-T16^T(=?KACC 19188^T?=?CCTCC AB 2016246^T).     

Effects of macrophyte leachate on <Emphasis Type="Italic">Anabaena</Emphasis> sp. and <Emphasis Type="Italic">Chlamydomonas moewusii</Emphasis> growth in freshwater tropical ecosystems

This study reports on the effects of dissolved organic matter (DOM) derived from the aquatic macrophyte Pistia stratiotes (collected from a tropical reservoir) on the mixotrophic growth of two phytoplankton species (Chlamydomonas moewusii and Anabaena sp.). The DOM from P. stratiotes had a mainly aliphatic structure, low molecular weight, low cellulose and lignin content and high carbon content. The addition of DOM (5% v/v) significantly decreased the growth rate of Anabaena sp. but increased the chlorophyll a concentration of C. moewusii. Higher light intensity (100 versus 30 µmol m^?2 s^?1) was important for Anabaena sp., increasing its growth rate and chlorophyll content. The use of DOM from P. stratiotes to mitigate cyanobacterial blooms should be further explored in future studies.     

Proposal of three novel species of soil bacteria, <Emphasis Type="Italic">Variovorax ureilyticus,Variovorax rhizosphaerae</Emphasis>, and <Emphasis Type="Italic">Variovorax robiniae</Emphasis>, in the family <Emphasis Type="Italic">Comamonadaceae</Emphasis>

Three novel bacterial strains (UCM-2^T, UCM-G28^T, and UCM-G35^T) were obtained while isolating soil bacteria for the development of antibiotics. Cells of these strains were Gram-negative, non-spore forming, motile by means of a single flagellum, and rod shaped. In all strains, the predominant isoprenoid quinone was ubiquinone-8 (Q-8). Cells contained C_16:0, summed feature 3 (C_16:1ω7c and/or C_16:1ω6c), summed feature 8 (C_18:1ω7c and/or C_18:1ω6c), and C_17:0 cyclo as the major fatty acids, and C_10:0 3-OH as the major hydroxy fatty acid. The polar lipid profiles of the three novel strains were dominated by diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. The genomic DNA G + C contents of strains UCM-2^T, UCM-G28^T, and UCMG35^T were 67.5, 65.9, and 66.4 mol%, respectively. Phylogenetic analyses based on 16S rRNA sequences showed that strain UCM-2^T was most closely related to Variovorax soli NBRC 106424^T, whereas strains UCM-G28^T and UCM-G35^T were most similar to Variovorax ginsengisoli Gsoil 3165^T. Values indicating DNA-DNA hybridization between the novel isolates and closely related species in the genus Variovorax were lower than the 70% cut-off point. These phenotypic, chemotaxonomic, and phylogenetic data indicate that the three isolates should be classified as new members of the genus Variovorax, for which the names Variovorax ureilyticus sp. nov., Variovorax rhizosphaerae sp. nov., and Variovorax robiniae sp. nov. are proposed. The type strains are UCM-2^T (= KACC 18899^T = NBRC 112306^T), UCMG28^T (= KACC 18900^T = NBRC 112307^T), and UCM-G35^T (= KACC 18901^T = NBRC 112308^T), respectively.     

Polymorphism in promoter regions of matrix metalloproteinases (<Emphasis Type="Italic">MMP1</Emphasis>, <Emphasis Type="Italic">MMP9</Emphasis>, and <Emphasis Type="Italic">MMP12</Emphasis>) in chronic obstructive pulmonary disease patients

Our studies have shown that the genotype and allele frequencies of polymorphisms G(?1607)GG of MMP1 gene, C(?1562)T of MMP9 gene, and A(?82)G of MMP12 gene do not significantly differ in the samples of chronic obstructive pulmonary disease (COPD) patients (N = 318) and healthy controls (N = 319) dwelling in Bashkortostan Republic. However, association of (?1562)T allele of the MMP9 gene with the severity of COPD disease progression has been revealed. In COPD patients at stage 4 of the disease, the frequency of allele T was significantly higher that in patients with the stages 2 and 3 (15.89% versus 8.38%; χ² = 7.804; d.f. = 1; P = 0.005; OR = 2.06 95% CI 1.22–3.49). The distribution of the genotype frequencies of C(?1562)T polymorphism of MMP9 gene significantly differed between the patients with various COPD severity (χ² = 9.849; d.f. = 2; P = 0.007). The individuals with rare genotype TT were revealed only among patients with severe COPD form (3.97% versus 0%; χ² = 4.78; P = 0.029; P _cor = 0.058). Analysis of this polymorphism in patients with early COPD onset (younger than 55 years old) has shown a significant increase in the allele T frequency in the group of patients with severe COPD (stage 4 according to GOLD) compared to the patients of the same age but with less severe COPD progression (χ² = 5.26; d.f. = 1; P = 0.022). As the major clinical characteristics of stage 4 COPD is the development of pulmonary emphysema as well as bronchial walls deformation, we suggest that the increased expression of MMP9 gene caused by genetic polymorphism in the gene promoter is important in the early development of serious complications of the disease.     

<Emphasis Type="Italic">Sphingorhabdus buctiana</Emphasis> sp. nov., isolated from fresh water,and reclassification of <Emphasis Type="Italic">Sphingopyxis contaminans</Emphasis> as <Emphasis Type="Italic">Sphingorhabdus contaminans</Emphasis> comb. nov.

A Gram-stain-negative, strictly aerobic, non-motile and rod-shaped bacterial strain, designated T5^T, was isolated from the Chishui River in Maotai town, Guizhou Province, Southwest of China. Strain T5^T was found to grow optimally at pH 9.0 and 25 °C. The 16S rRNA gene sequence analysis indicated that strain T5^T belongs to the family Sphingomonadaceae within the phylum Proteobacteria; the strain T5^T clustered with the type strains of Sphingopyxis contaminans, Sphingorhabdus wooponensis and Sphingorhabdus rigui, with which it exhibits 16S rRNA gene sequence similarity values of 96.2–96.9%. The DNA G+C content was 58.5 mol%. The major respiratory quinone was Q-10 and the major polar lipid was phosphatidylethanolamine. The major polyamine was homospermidine and the major fatty acids were C_18:1 ω7c (37.5%) and C_16:1 ω7c (30.1%). On the basis of phylogenetic, phenotypic and genetic data, strain T5^T represents a novel species of the genus Sphingorhabdus, for which the name Sphingorhabdus buctiana sp. nov. is proposed. The type strain is T5^T (= CGMCC 1.12929^T = JCM 30114^T). It is also proposed that Sphingopyxis contaminans should be reclassified as a member of the genus Sphingorhabdus.     

Deletion of <Emphasis Type="Italic">ldh</Emphasis>A and <Emphasis Type="Italic">ald</Emphasis>H genes in <Emphasis Type="Italic">Klebsiella</Emphasis><Emphasis Type="Italic">pneumoniae</Emphasis> to enhance 1,3-propanediol production

Objectives

To improve 1,3-propanediol (1,3-PD) production and reduce byproduct concentration during the fermentation of Klebsiella pneumonia.

Results

Klebsiella. pneumonia 2-1ΔldhA, K. pneumonia 2-1ΔaldH and K. pneumonia 2-1ΔldhAΔaldH mutant strains were obtained through deletion of the ldhA gene encoding lactate dehydrogenase required for lactate synthesis and the aldH gene encoding acetaldehyde dehydrogenase involved in the synthesis of ethanol. After fed-batch fermentation, the production of 1,3-PD from glycerol was enhanced and the concentrations of byproducts were reduced compared with the original strain K. pneumonia 2-1. The maximum yields of 1,3-PD were 85.7, 82.5 and 87.5 g/l in the respective mutant strains.

Conclusion

Deletion of either aldH or ldhA promoted 1,3-PD production in K. pneumonia.

     

Rnq1 protein protects [<Emphasis Type="Italic">PSI</Emphasis><Superscript>+</Superscript>] prion from effect of the <Emphasis Type="Italic">PNM</Emphasis> mutation

The interaction of [PSI ⁺] and [PIN ⁺] factors in yeast Saccharomyces cerevisiae is known as the first evidence of prions networks. In [PIN ⁺] cells, Rnq1p prion aggregates work as a template for Sup35p aggregation, which is essential for [PSI ⁺] induction. No additional factors are required for subsequent Sup35p aggregation. Nevertheless, several recent reports provide data that indicate a more complex interplay between these prions. Our results show that the presence of Rnq1p in the cell significantly decreases the loss of [PSI ⁺] prion, which is caused by a double mutation in SUP35 (Q61K, Q62K substitutions in the Sup35 protein). These observations support the existence of interaction networks that converge on a strong linkage of prionogenic and prion-like proteins, and the participation of Rnq1 protein in the maintenance of prion [PSI ⁺].     

<Emphasis Type="Italic">Paenibacillus bryophyllum</Emphasis> sp. nov., a nitrogen-fixing species isolated from <Emphasis Type="Italic">Bryophyllum pinnatum</Emphasis>

A nitrogen-fixing, endospore-forming bacterium, designated strain L201^T was isolated from the leaves of Bryophyllum pinnatum growing in South China Agricultural University. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain L201^T is affiliated with the genus Paenibacillus, and closely related to Paenibacillus albidus Q4-3^T (97.4%), Paenibacillus odorifer DSM 15391^T (97.3%) and Paenibacillus borealis DSM 13188^T (97.2%). The main fatty acids components was anteiso-C_15:0 (48.1%). The predominant isoprenoid quinone was MK-7. The major polar lipids were found to be diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The G+C content of strain L201^T was 43.9%. DNA–DNA relatedness between L201^T and the reference strain was 29.8%. Biological and biochemical tests, protein patterns, genomic DNA fingerprinting and comparison of cellular fatty acids distinguished strain L201^T from the closely related Paenibacillus species. Based on these data, the novel species Paenibacillus bryophyllum sp. nov. is proposed, with the type strain L201^T(=?KCTC 33951 ^T?=?GDMCC 1.1251 ^T).     

Structural organization characteristics of the <Emphasis Type="Italic">DIP1</Emphasis> gene in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> strains mutant for the <Emphasis Type="Italic">flamenco</Emphasis> gene

Molecular cloning of the DIP1 gene located in the 20A4-5 region has been performed from the following strains with the flamenco phenotype: flam ^SS (SS) and flam ^MS (MS) characterized by a high transposition rate of retrotransposon gypsy (mdg4), flam ^{py + (P)} carrying the insertion of a construction based on the P element into the region of the flamenco gene, and flamenco ⁺. The results of restriction analysis and sequencing cloned DNA fragments has shown that strains flam ^SS , flam ^MS considerably differ from flam ^{py + (P)}, and flamenco ⁺ in the structure of DIP1. Strains flam ^SS and flam ^MS have no DraI restriction site at position 1765 in the coding region of the gene, specifically, in the domain determining the signal of the nuclear localization of the DIP1 protein. This mutation has been found to consist in a nucleotide substitution in the recognition site of DraI restriction endonuclease, which is transformed from TTTAAA into TTTAAG and, hence, is not recognized by the enzyme. This substitution changes codon AAA into AAG and is translationally insignificant, because both triplets encode the same amino acid, lysine. The DIP1 gene of strains flam ^SS and flam ^MS has been found to contain a 182-bp insertion denoted IdSS (insertion in DIP1 strain SS); it is located in the second intron of the gene. The IdSS sequence is part of the open reading frame encoding the putative transposase of the mobile genetic element HB1 belonging to the Tc1/mariner family. This insertion is presumed to disturb the conformations of DNA and the chromosome, in particular, by forming loops, which alters the expression of DIP1 and, probably, neighboring genes. In strains flamenco ⁺ and flam ^{py + (P)}, the IdSS insertion within the HB1 sequence is deleted. The deletion encompasses five C-terminal amino acid residues of the conserved domain and the entire C-terminal region of the putative HB1 transposase. The obtained data suggest that DIP1 is involved in the control of gypsy transpositions either directly or through interaction with other elements of the genome.     

Mode of action of leucocin K7 produced by <Emphasis Type="Italic">Leuconostoc mesenteroides</Emphasis> K7 against <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> and its potential in milk preservation

Objectives

To investigate the mode of action of leucocin K7 against Listeria monocytogenes and to assess its inhibitory effect on Lis. monocytogenes in refrigerated milk.

Results

A bacteriocin-producing strain, Leuconostoc mesenteroides K7, was isolated from a fermented pickle. The bacteriocin, leucocin K7, exhibited antagonistic activity against Lis. monocytogenes with an MIC of 28 µg/ml. It was sensitive to proteaseS and displayed good thermal stability and broad active pH range. Leucocin K7 had no effect on the efflux of ATP from Lis. monocytogenes but triggered the efflux of K⁺ and the intracellular hydrolysis of ATP. It also dissipated the transmembrane electrical potential completely and transmembrane pH gradient partially. It 80 AU/ml inhibited the growth of Lis. monocytogenes by 2.3–3.9 log units in milk; when combined with glycine (5 mg/ml), it completely eliminated viable Lis. monocytogenes over 7 days

Conclusion

Leucocin K7 shows different mode of action from nisin and may have potential application in milk preservation.

     

A putative <Emphasis Type="Italic">NEM1</Emphasis> homologue regulates lipid droplet biogenesis <Emphasis Type="Italic">via PAH1</Emphasis> in <Emphasis Type="Italic">Tetrahymena thermophila</Emphasis>

Nuclear envelope morphology protein 1 (NEM1) along with a phosphatidate phosphatase (PAH1) regulates lipid homeostasis and membrane biogenesis in yeast and mammals. We investigated four putative NEM1 homologues (TtNEM1A, TtNEM1B, TtNEM1C and TtNEM1D) in the Tetrahymena thermophila genome. Disruption of TtNEM1B, TtNEM1C or TtNEM1D did not compromise normal cell growth. In contrast, we were unable to generate knockout strain of TtNEM1A under the same conditions, indicating that TtNEM1A is essential for Tetrahymena growth. Interestingly, loss of TtNEM1B but not TtNEM1C or TtNEM1D caused a reduction in lipid droplet number. Similar to yeast and mammals, TtNem1B of Tetrahymena exerts its function via Pah1, since we found that PAH1 overexpression rescued loss of Nem1 function. However, unlike NEM1 in other organisms, TtNEM1B does not regulate ER/nuclear morphology. Similarly, neither TtNEM1C nor TtNEM1D is required to maintain normal ER morphology. While Tetrahymena PAH1 was shown to functionally replace yeast PAH1 earlier, we observed that Tetrahymena NEM1 homologues did not functionally replace yeast NEM1. Overall, our results suggest the presence of a conserved cascade for regulation of lipid homeostasis and membrane biogenesis in Tetrahymena. Our results also suggest a Nem1-independent function of Pah1 in the regulation of ER morphology in Tetrahymena.     

The <Emphasis Type="Italic">alm1</Emphasis><Superscript><Emphasis Type="Italic">+</Emphasis></Superscript> gene from <Emphasis Type="Italic">Schizosaccharomyces pombe</Emphasis> encodes a coiled-coil protein that associates with the medial region during mitosis

We have isolated a cDNA that encodes a 142-kDa protein by immunoscreening of a Schizosaccharomyces pombe expression library with a new antibody, mAb8, that reveals spindle poles and equatorial ring-like structures in several organisms. This cDNA encodes a putative protein which we termed Alm (for abnormal long morphology). The protein is predicted to be a coiled-coil protein, containing a central α-helical domain flanked by non-helical terminal domains. Immunofluorescence analysis showed that Alm1 is localized in the medial region of the cell from anaphase to the end of cytokinesis. Cells carrying an alm1::ura4 ⁺ disruption are viable and exhibit an elongated morphology. Homozygous alm1::ura4 ⁺ diploids sporulated normally but the spores did not germinate. Spores that have inherited the disruption allele from a heterozygous alm1 ⁺ / alm1::ura4 ⁺ diploid germinated but generated smaller colonies. We propose that Alm1 participates in the structural organization of the medial region in S. pombe.     

<Emphasis Type="Italic">Candida krusei</Emphasis> and <Emphasis Type="Italic">Candida glabrata</Emphasis> reduce the filamentation of <Emphasis Type="Italic">Candida albicans</Emphasis> by downregulating expression of <Emphasis Type="Italic">HWP1</Emphasis> gene

Pathogenicity of Candida albicans is associated with its capacity switch from yeast-like to hyphal growth. The hyphal form is capable to penetrate the epithelial surfaces and to damage the host tissues. Therefore, many investigations have focused on mechanisms that control the morphological transitions of C. albicans. Recently, certain studies have showed that non-albicans Candida species can reduce the capacity of C. albicans to form biofilms and to develop candidiasis in animal models. Then, the objective of this study was to evaluate the effects of Candida krusei and Candida glabrata on the morphogenesis of C. albicans. Firstly, the capacity of reference and clinical strains of C. albicans in forming hyphae was tested in vitro. After that, the expression of HWP1 (hyphal wall protein 1) gene was determined by quantitative real-time PCR (polymerase chain reaction) assay. For both reference and clinical strains, a significant inhibition of the hyphae formation was observed when C. albicans was incubated in the presence of C. krusei or C. glabrata compared to the control group composed only by C. albicans. In addition, the culture mixed of C. albicans-C. krusei or C. albicans-C. glabrata reduced significantly the expression of HWP1 gene of C. albicans in relation to single cultures of this specie. In both filamentation and gene expression assays, C. krusei showed the higher inhibitory activity on the morphogenesis of C. albicans compared to C. glabrata. C. krusei and C. glabrata are capable to reduce the filamentation of C. albicans and consequently decrease the expression of the HWP1 gene.     

<Emphasis Type="Italic">Rhizobium</Emphasis> strains in the biological control of the phytopathogenic fungi <Emphasis Type="Italic">Sclerotium</Emphasis> (<Emphasis Type="Italic">Athelia</Emphasis>) <Emphasis Type="Italic">rolfsii</Emphasis> on the common bean

Aims

To identify Rhizobium strains’ ability to biocontrol Sclerotium rolfsii, a fungus that causes serious damage to the common bean and other important crops, 78 previously isolated rhizobia from common bean were assessed.

Methods

Dual cultures, volatiles, indole-acetic acid (IAA), siderophore production and 16S rRNA sequencing were employed to select strains for pot and field experiments.

Results

Thirty-three antagonistic strains were detected in dual cultures, 16 of which were able to inhibit ≥84% fungus mycelial growth. Antagonistic strains produced up to 36.5 μg mL^?1 of IAA, and a direct correlation was verified between IAA production and mycelium inhibition. SEMIA 460 inhibited 45% of mycelial growth through volatile compounds. 16S rRNA sequences confirmed strains as Rhizobium species. In pot condition, common bean plants grown on S. rolfsii-infested soil and inoculated with SEMIA 4032, 4077, 4088, 4080, 4085, or 439 presented less or no disease symptoms. The most efficient strains under field conditions, SEMIA 439 and 4088, decreased disease incidence by 18.3 and 14.5% of the S. rolfsii-infested control.

Conclusions

Rhizobium strains could be strong antagonists towards S. rolfsii growth. SEMIA 4032, 4077, 4088, 4080, 4085, and 439 are effective in the biological control of the collar rot of the common bean.

     

<Emphasis Type="Italic">Flavobacterium zaozhuangense</Emphasis> sp. nov., a new member of the family <Emphasis Type="Italic">Flavobacteriaceae</Emphasis>, isolated from metolachlor-contaminated soil

Strain ZZ-8^T, a Gram-negative, aerobic, non-spore-forming, non-motile, yellow-pigmented, rod-shaped bacterium, was isolated from metolachlor-contaminated soil in China. The taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZZ-8^T is a member of the genus Flavobacterium and shows high sequence similarity to Flavobacterium humicola UCM-46^T (97.2%) and Flavobacterium pedocola UCM-R36^T (97.1%), and lower (<?97%) sequence similarity to other known Flavobacterium species. Chemotaxonomic analysis revealed that strain ZZ-8^T possessed MK-6 as the major respiratory quinone; and iso-C_15:0 (28.5%), summed feature 9 (iso-C_17:1 w9c/C_16:0 10-methyl, 22.9%), iso-C_17:0 3-OH (17.0%), iso-C_15:0 3-OH (8.9%), iso-C_15:1 G (8.6%) and summed feature 3 (C_16:1 w7c/C_16:1 w6c, 5.7%) as the predominant fatty acids. The polar lipids of strain ZZ-8^T were determined to be lipids, a glycolipid, aminolipids and phosphatidylethanolamine. Strain ZZ-8^T showed low DNA–DNA relatedness with F. pedocola UCM-R36^T (43.23?±?4.1%) and F. humicola UCM-46^T (29.17?±?3.8%). The DNA G+C content was 43.3 mol%. Based on the phylogenetic and phenotypic characteristics, chemotaxonomic data and DNA–DNA hybridization, strain ZZ-8^T is considered a novel species of the genus Flavobacterium, for which the name Flavobacterium zaozhuangense sp. nov. (type strain ZZ-8^T?=?KCTC 62315 ^T?=?CCTCC AB 2017243^T) is proposed.