Control of postharvest soft rot caused by <Emphasis Type="Italic">Erwinia carotovora</Emphasis> of vegetables by a strain of <Emphasis Type="Italic">Bacillus amyloliquefaciens</Emphasis> and its potential modes of action

Erwinia carotovora subsp. carotovora (Ecc), the causal agent of bacterial soft rot, is one of the destructive pathogens of postharvest vegetables. In this study, a bacterial isolate (BGP20) from the vegetable farm soil showed strong antagonistic activity against Ecc in vitro, and its twofold cell-free culture filtrate showed excellent biocontrol effect in controlling the postharvest bacterial soft rot of potatoes at 25 °C. The anti-Ecc metabolites produced by the isolate BGP20 had a high resistance to high temperature, UV-light and protease K. Based on the colonial morphology, cellular morphology, sporulation, and partial nucleotide sequences of 16S rRNA and gyrB gene, the isolate BGP20 was identified as Bacillus amyloliquefaciens subsp. plantarum. Further in vivo assays showed that the BGP20 cell culture was more effective in controlling the postharvest bacterial soft rot of green peppers and Chinese cabbages than its twofold cell-free culture filtrate. In contrast, the biocontrol effect and safety of the BGP20 cell culture were very poor on potatoes. In the wounds of potatoes treated with both the antagonist BGP20 and the pathogen Ecc, the viable count of Ecc was 31,746 times that of BGP20 at 48 h of incubation at 25 °C. But in the wounds of green peppers, the viable count of BGP20 increased 182.3 times within 48 h, and that of Ecc increased only 51.3 %. In addition, the treatment with both BGP20 and Ecc induced higher activity of phenylalanine ammonia-lyase (PAL) than others in potatoes. But the same treatment did not induce an increase of PAL activity in green peppers. In conclusion, the present study demonstrated that the isolate BGP20 is a promising candidate in biological control of postharvest bacterial soft rot of vegetables, but its main mode of action is different among various vegetables.     

Beneficial native bacteria improve survival and mycorrhization of desert truffle mycorrhizal plants in nursery conditions

Sixty-four native bacterial colonies were isolated from mycorrhizal roots of Helianthemum almeriense colonized by Terfezia claveryi, mycorrhizosphere soil, and peridium of T. claveryi to evaluate their effect on mycorrhizal plant production. Based on the phylogenetic analysis of the 16S rDNA partial sequence, 45 different strains from 17 genera were gathered. The largest genera were Pseudomonas (40.8 % of the isolated strains), Bacillus (12.2 % of isolated strains), and Varivorax (8.2 % of isolated strains). All the bacteria were characterized phenotypically and by their plant growth-promoting rhizobacteria (PGPR) traits (auxin and siderophore production, phosphate solubilization, and ACC deaminase activity). Only bacterial combinations with several PGPR traits or Pseudomonas sp. strain 5, which presents three different PGPR traits, had a positive effect on plant survival and growth. Particularly relevant were the bacterial treatments involving auxin release, which significantly increased the root-shoot ratio and mycorrhizal colonization. Moreover, Pseudomonas mandelii strain 29 was able to considerably increase mycorrhizal colonization but not plant growth, and could be considered as mycorrhiza-helper bacteria. Therefore, the mycorrhizal roots, mycorrhizosphere soil, and peridium of desert truffles are environments enriched in bacteria which may be used to increase the survival and mycorrhization in the desert truffle plant production system at a semi-industrial scale.     

Analysis of fatty acid composition of PGPR <Emphasis Type="Italic">Klebsiella</Emphasis> sp. SBP-8 and its role in ameliorating salt stress in wheat

A halotolerant plant-growth-promoting rhizobacteria (PGPR) can ameliorate salt stress in associated plants by various mechanisms. Therefore, the present study aimed to characterize a PGPR Klebsiella sp. SBP-8 for its ability to tolerate salt stress and to study the mechanism of PGPR-mediated mitigation of salt stress in the wheat plant. The abiotic stressors result in multiple changes in the fatty acid composition of Klebsiella sp. SBP-8, helping the membrane to keep its integrity, fluidity, and function for its growth under salt (NaCl) stress conditions. The changes in fatty acid composition of test organism were analyzed by fatty acid methyl ester (FAME) analysis under varying saline conditions. The spectroscopy (GC-MS) profile of cell extract at different salt concentrations was comprised of hydrocarbons, and fatty alcohols with varying carbon chain length. Inoculation of Klebsiella sp. SBP-8 to wheat seedling showed increase in proline, total soluble sugar, and total protein content of treated plants. Bacterial inoculation also decreased the concentration of salinity-induced malondialdehyde (MDA) content. In addition, bacterial inoculation also increased the various antioxidative enzymes like superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) in treated plants. It is likely that bacterial inoculation alleviated the salt stress to wheat plant by co-ordination of antioxidative machinery, and improvement in osmolyte contents. Therefore, the present study suggests that bacterial-inoculated wheat plants were able to cope better with salt stress than uninoculated control, therefore it can serve as a promising bio-inoculant for enhancing the growth of wheat like cereal crops under saline stress.     

<Emphasis Type="Italic">Rhizobium</Emphasis> as plant probiotic for strawberry production under microcosm conditions

There is increasing interest in the use of plant growth-promoting rhizobacteria (PGPR) as environmental-friendly and healthy biofertilizers. Strawberries (Fragraria x ananassa) are mainly consumed fresh and hence any PGPRs used for biofertilization must be safe for humans, which is the case for members of the genus Rhizobium. In this study, the effects of inoculation of strawberry plants with Rhizobium sp. strain PEPV16, which belongs to the phylogenetic group of R. leguminosarum, and whose plant growth promotion ability has been reported previously for lettuce (Lactuca sativa) and carrots (Daucus carota), was examined. The results demonstrated that PEPV16 promotes strawberry growth through significant increases in the number of stolons, flowers and fruits as compared with uninoculated controls. Compared to uninoculated controls, the fruits of the inoculated plants had higher concentrations of Fe, Zn, Mn and Mo, and they also had higher concentrations of organic acids, such as citric and malic acid, and lower amounts of ascorbic acid than fruits. Although decreases in ascorbic acid have previously been described after the inoculation of strawberry with strains from different PGPR genera, this is the first study to report increases in organic acids after PGPR inoculation.     

Impact of <Emphasis Type="Italic">Phanerochaete chrysosporium</Emphasis> inoculation on indigenous bacterial communities during agricultural waste composting

This research was conducted to distinguish between the separate effects of the Phanerochaete chrysosporium inoculation and sample property heterogeneity induced by different inoculation regimes on the indigenous bacterial communities during agricultural waste composting. P. chrysosporium was inoculated during different phases. The bacterial community abundance and structure were determined by quantitative PCR and denaturing gradient gel electrophoresis analysis, respectively. Results indicated a significant stimulatory effect of P. chrysosporium inoculation on the bacterial community abundance. The bacterial community abundance significantly coincided with pile temperature, ammonium, and nitrate (P?<?0.006). Variance partition analysis showed that the P. chrysosporium inoculation directly explained 20.5 % (P?=?0.048) of the variation in the bacterial communities, whereas the sample property changes induced by different inoculation regimes indirectly explained up to 35.1 % (P?=?0.002). The bacterial community structure was significantly related to pile temperature, water-soluble carbon (WSC), and C/N ratio when P. chrysosporium were inoculated. The C/N ratio solely explained 7.9 % (P?=?0.03) of the variation in community structure, whereas pile temperature and WSC explained 7.7 % (P?=?0.026) and 7.5 % (P?=?0.034) of the variation, respectively. P. chrysosporium inoculation affected the indigenous bacterial communities most probably indirectly through increasing pile temperature, enhancing the substrate utilizability, and changing other physico-chemical factors.     

Molecular diversity of 1-aminocyclopropane-1-carboxylate (ACC) deaminase producing PGPR from wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) rhizosphere

Aims

The present study was planned to investigate the diversity of 1-aminocyclopropane-1-carboxylate (ACC) deaminase producing bacteria from the rhizosphere of wheat plants and subsequent evaluation of selected PGPR on growth enhancement of wheat seedlings under drought and saline conditions.

Methods

ACC deaminase producing plant growth promoting rhizobacteria (PGPR) were isolated from the rhizosphere of wheat and identified using 16S rRNA gene sequence analysis. Isolates were evaluated for various direct and indirect plant growth promoting (PGP) traits. Plant inoculation experiment was conducted using isolates IG 19 and IG 22 in wheat to assess their plant growth promotion potential under salinity and drought stress.

Results

Thirty-eight ACC deaminase producing PGPR were isolated which belonged to 12 distinct genera and falling into four phyla γ-proteobacteria, β-proteobacteria, Flavobacteria and Firmicutes. Klebsiella sp. was the most abundant genera and followed by Enterobacter sp. The isolates exhibited ACC deaminase activities ranging from 0.106–0.980 μM α- ketobutyrate μg protein^?1 h^?1. The isolates showed multiple PGP traits such as IAA production, phosphate, zinc, potassium solubilization and siderophore production. Enterobacter cloacae (IG 19) and Citrobacter sp. (IG 22) inoculated wheat seedlings showed notable increases in fresh and dry biomass under non-stress as well as under stressed condition.

Conclusion

To the best of our knowledge this is the first report of presence of ACC deaminase activity and other PGP traits from the genus Citrobacter and Empedobacter. Our finding revealed that the γ-proteobacteria group dominated the wheat rhizosphere. Plant inoculation with PGPR could be a sustainable approach to alleviate abiotic stresses in wheat plants. These native PGPR isolates could be used as potential biofertilizers for sustainable agriculture.

     

<Emphasis Type="Italic">Stenotrophomonas maltophilia</Emphasis> HW2 enhanced cucumber resistance against cucumber green mottle mosaic virus

Cucumber green mottle mosaic virus (CGMMV) is a major limiting factor in the production of cucumber plants worldwide. In the present study, we use plant growth-promoting rhizobacteria (PGPR) to control this virus effectively. Stenotrophomonas maltophilia HW2 was isolated from healthy cucumber root, exhibited a good biocontrol efficacy against CGMMV. Here, it is documented that 20 d after virus inoculation, the biocontrol efficacy of HW2 reached 52.61%. HW2 can effectively colonize in cucumber rhizosphere, and also promoted cucumber plants growth. We also examined the effect of HW2 on viral replication and its mechanism. Compared with the control, HW2 pre-treated plants could delay virus replication for more than 3 d and inhibit viral protein genes (CP, MP, Rep) expression in the cucumber leaf. The expression of antioxidant enzyme genes (SOD and CAT) and defense-related genes (PR1 and PR5) were quickly induced by HW2. These results suggest that HW2 induced plant defense responses to CGMMV by increasing the expression of defense response genes. We report for the first time that Stenotrophomonas maltophilia improved cucumber resistance against CGMMV, which highlights the applying of PGPR on controlling of virus diseases.     

Reduction of soil-borne pathogen <Emphasis Type="Italic">Fusarium solani</Emphasis> reproduction in soil enriched with phenolic acids by inoculation of endophytic fungus <Emphasis Type="Italic">Phomopsis liquidambari</Emphasis>

The increase of soil-borne pathogens induced by phenolic acids that accumulate in continuous cropping soil reduces the yield and quality of crops. The aims of this study were to investigate (i) the biological control of Fusarium solani, in soil enriched with phenolic acids, by the inoculation of the endophytic fungus Phomopsis liquidambari, and (ii) the biocontrol mechanisms involved. Inoculation of P. liquidambari significantly inhibited the reproduction of F. solani. The prompt degradation of soil phenolic acids by P. liquidambari was determined, but no direct antagonism relationship was observed between P. liquidambari and F. solani, implying the alleviated stimulation of phenolic acids was a major factor in controlling F. solani. Moreover, the presence of glucose did not significantly impact the biocontrol function of P. liquidambari, and P. liquidambari inoculation significantly alleviated disease severity of peanut. Therefore, P. liquidambari could be an effective means to control F. solani in phenolic acids-rich continuous cropping soils.     

Physiological and biochemical changes in tomato cultivar PT-3 with dual inoculation of mycorrhiza and PGPR against root-knot nematode

Arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) have potential to control soil-borne diseases including plant-parasitic nematodes. First, the effects of dual inoculation of mycorrhiza (Rhizophagus irregularis) and two stains of pseudomonads (Pseudomonas jessenii strain R62 and Pseudomonas synxantha strain R81) on tomato (Solanum lycopersicum cv. PT-3) growth were tested. Further, the physiological and biochemical changes caused by these beneficial organisms during infection by the root-knot nematode Meloidogyne incognita were studied. The experiment was conducted under glass house conditions and carried out up to one month after nematode inoculation. Plants treated with dual or individual inoculation of AMF and PGPR showed significantly enhanced plant growth and reduced nematode infection. In addition, they exhibited potent activity of phenolics (28 %) and defensive enzymes i.e. peroxidase (PO; 1.26 fold), polyphenyloxidase (PPO; 1.35 fold) and superoxide dismutase (SOD; 1.09 fold) while a significant reduction in malondialdehyde (MDA; 1.63 fold) and hydrogen peroxide (H₂O₂; 1.30 fold) content was recorded when compared to the nematode-infected plants. These findings indicate the feasibility of AMF and PGPR individually or in combinations as potential biocontrol agents for the management of root-knot nematodes.     

Characterization of phosphate-solubilizing bacteria exhibiting the potential for growth promotion and phosphorus nutrition improvement in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) in calcareous soils of Sinaloa,Mexico

Greenhouse bioassays were used to examine the ability of selected strains of the rhizobacteria Sinorhizobium meliloti, Bacillus flexus and B. megaterium to solubilize phosphorus (P) and to affect growth promotion and phosphorus nutrition in maize. These bacterial strains were found to decrease the pH and solubilize some forms of insoluble P, such as tricalcium phosphate and hydroxyapatite, as well as to exhibit acid and alkaline phosphatase enzymatic activities in culture medium, properties that are possibly involved in P solubilization. Inoculation of the strains separately and as a consortium of the three bacteria (S. meliloti, B. flexus and B. megaterium) in P-deficient soil (4.33 w/v P) fertilized without P improved plant height, shoot and root dry weight, as well as P nutrition in the maize plants. Use of the B. flexus and B. megaterium strains separately and in a consortium positively affected several growth parameters and P nutrition in plants supplemented with insoluble P. No effect was observed when pots in which the seedlings were growing were supplied with soluble fertilizer. A second assay using a P-deficient soil (6.64 w/v P) showed that inoculation with the consortium of B. flexus and B. megaterium significantly increased growth and total P content in maize plants. A dose–response P fertilization experiment using sterile P-deficient soil led us to conclude that inoculation to soil of the mixture of B. flexus and B. megaterium may improve P nutrition and growth to a level previously attained by the addition of soluble P-fertilizer at 40 w/v P. A non-sterile experiment showed a beneficial response with B. megaterium but not with B. flexus. We propose utilizing these bacteria in P-deficient alkaline soils in future field trials in order to evaluate their potential as biofertilizers.     

<Emphasis Type="Italic">Larkinella roseus</Emphasis> sp. nov., a species of the family <Emphasis Type="Italic">Cytophagaceae</Emphasis> isolated from beach soil

The taxonomic position of bacterial strain, designated 15J16-1T3A^T, recovered from a soil sample was established using a polyphasic approach. Phylogenic analysis based on the 16S rRNA gene sequence showed that strain 15J16-1T3A^T belonged to the family Cytophagaceae, phylum Bacteroidetes, and was most closely related to ‘Larkinella harenae’ 15J9-9 (95.9% similarity), Larkinella ripae 15J11-11^T (95.6%), Larkinella bovis M2TB15^T (94.7%), Larkinella arboricola Z0532^T (93.9%), and Larkinella insperata LMG 22510^T (93.5%). Cells were rod-shaped, Gram-stain-negative, aerobic, and nonmotile. The isolate grew on NA, R2A, TSA, but not on LB agar. The strain was able to grow at temperature range from 10°C to 30°C with an optimum at 25°C and pH 6–8. Menaquinone MK-7 was the predominant respiratory quinone. The major cellular fatty acids comprised C_16:1ω5c (48.6%) and C_15:0 iso (24.1%). Phosphatidylethanolamine, phosphatidylserine, and an unidentified lipid were the major polar lipids. The G + C content of the genomic DNA was 49.5 mol%. Strain 15J16-1T3A^T could be distinguished from its closest phylogenetic neighbors based on its phenotypic, genotypic, and chemotaxonomic features. Therefore, the isolate is considered to represent a novel species in the genus Larkinella, for which the name Larkinella roseus sp. nov. is proposed. The type strain is 15J16-1T3A^T (= KCTC 52004^T = JCM 31991^T).     

Biodegradation of phenol, <Emphasis Type="Italic">o-</Emphasis>cresol, <Emphasis Type="Italic">m-</Emphasis>cresol and <Emphasis Type="Italic">p-</Emphasis>cresol by indigenous soil fungi in soil contaminated with creosote

Seven non-basidiomycetic fungi, Aspergillus, Candida, Cladosporium, Fusarium, Monicillium, Trichoderma and Penicillium, and two basidiomycetic fungi, Pleurotus and Phanerochaete were isolated from a creosote-contaminated soil by using mineral salts medium and soil extract broth containing antibiotics. Soil contaminated with phenol, o-cresol, m-cresol and p-cresol was collected from the yard of a wood treatment plant in South Africa and inoculated with the strains of Aspergillus, Cladosporium, Fusarium, Monicillium, Penicillium and Phanerochaete, selected from the isolate. The soil in some of the treatment reactors was amended with nutrient supplements to give a C:N:P ratio of 25:5:1. A total of 18 duplicate treatments were established and incubated in the dark at 25°C for 70days. The soil in all the reactors was tilled weekly and moisture was maintained at 70% field capacity. Soil samples were collected every 2weeks for analysis of residual concentrations of the phenols tested, pH measurement and moisture content determination. The nutrient-supplemented treatments were more effective in degrading the phenols (between 84 and 100%) than those that were not supplemented. Barley, which was used as bulking agent enhanced the growth of the fungi and subsequently the degradation of the phenols. Inoculation with a mixture of the six fungal isolates promoted more phenol degradation than with single isolates.     

Growth and nodulation in <Emphasis Type="Italic">Alnus sieboldiana</Emphasis> in response to <Emphasis Type="Italic">Frankia</Emphasis> inoculation and nitrogen treatments

Key message

We investigated a Frankia – Alnus sieboldiana symbiosis, including the minimum inoculum dose for constant nodulation, the period of time to nodulation after inoculation, and the effects of N on nodulation.

Abstract

Frankia is a nitrogen-fixing actinomycete that forms root nodules in some dicotyledonous plants, which are called actinorhizal. We studied nodule formation in Alnus sieboldiana, an actinorhizal plant, after inoculation with a Frankia isolate to establish techniques for Frankia inoculation and the cultivation of inoculated plants. Root nodules formed on seedlings of A. sieboldiana by 2 weeks after inoculation, and N₂ fixation measured by acetylene reduction activity started 3 weeks after inoculation. Nodulation was observed after inoculation with a Frankia isolate at 0.001 μL packed cell volume (pcv). The number of nodules formed on the seedlings inoculated with Frankia at more than 0.05 μL pcv was not significantly different. Nodule development and N₂ fixation were reduced when inoculated seedlings were treated weekly with 15 mM NH₄NO₃-N. In contrast, treatment with 3.75 or 0.9375 mM NH₄NO₃-N did not inhibit nodule development or N₂ fixation of inoculated seedlings by 15 weeks of N treatment.

     

Quorum sensing activity of the plant growth-promoting rhizobacterium <Emphasis Type="Italic">Serratia glossinae</Emphasis> GS2 isolated from the sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) rhizosphere

Plant growth-promoting rhizobacteria (PGPR) affect plant growth through various mechanisms, such as indole-3-acetic acid (IAA) production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and biofilm formation. The aim of the study reported here was to isolate and characterize rhizobacteria that produce quorum-sensing signal molecules and other PGPR-related molecules. A biofilm-forming bacterium, GS2, was isolated from the rhizosphere of a sesame plant and subsequently found to produce two quorum-sensing signal molecules that were identified as N-hexanoyl-L-homoserine lactone (m/z 200) and N-octanoyl-L-homoserine lactone (m/z 228) by liquid chromatography–tandem mass spectrometry analysis. The strain was also found to produce IAA (17.2 μg mL^?1), gibberellins (113.7 μg mL^?1), and ACC deaminase (9.7 μM α-ketobutyrate mg^?1 protein h^?1). The strain was identified as Serratia glossinae based on a comparison of 16S rRNA gene sequences. Inoculation of the strain promoted growth of a gibberellin-deficient rice dwarf mutant (Waito-C). Different growth attributes, including shoot and root elongation, chlorophyll content, and plant weight could be attributed to the PGPR characteristics of strain GS2. These results suggest that S. glossinae strain GS2 can serve as a microbial agent that improves plant growth.     

Impact of high temperature on sucrose translocation,sugar content and inulin yield in <Emphasis Type="Italic">Cichorium intybus</Emphasis> L. var. <Emphasis Type="Italic">sativum</Emphasis>

Aims

Dianthus caryophyllus is a commercially important ornamental flower. Plant growth promoting rhizobacteria are increasingly applied as bio-fertilisers and bio-fortifiers. We studied the effect of a rhizospheric isolate Klebsiella SGM 81 strain to promote D. caryophyllus growth under sterile and non-sterile conditions, to colonise its root system endophytically and its impact on the cultivatable microbial community. We identified the auxin indole-3-acetic acid (IAA) production of Klebsiella SGM 81 as major bacterial trait most likely to enhance growth of D. caryophyllus.

Methods

ipdC dependent IAA production of SGM 81 was quantified using LC-MS/MS and localised proximal to D. caryophyllus roots and correlated to root growth promotion and characteristic morphological changes. SGM 81 cells were localised on and within the plant root using 3D rendering confocal microscopy of gfp expressing SGM 81. Using Salkowski reagent IAA production was quantified and localised proximal to roots in situ. The effect of different bacterial titres on rhizosphere bacterial population was CFU enumerated on nutrient agar. The genome sequence of Klebsiella SGM 81 (accession number PRJEB21197) was determined to validate PGP traits and phylogenic relationships.

Results

Inoculation of D. caryophyllus roots with Klebsiella SGM 81 drastically promoted plant growth when grown in agar and soil, concomitant with a burst in root hair formation, suggesting an increase in root auxin activity. We sequenced the Klebsiella SGM 81 genome, identified the presence of a canonical ipdC gene in Klebsiella SGM 81, confirmed bacterial production and secretion of IAA in batch culture using LC-MS/MS and localised plant dependent IAA production by SGM 81 proximal to roots. We found Klebsiella SGM 81 to be a rhizoplane and endophytic coloniser of D. caryophyllus roots in a dose dependent manner. We found no adverse effects of SGM 81 on the overall rhizospheric microbial population unless supplied to soil in very high titres.

Conclusion

Klebsiella SGM 81 effectively improves root traits of D. caryophyllus in a dose dependent manner, likely through tryptophan dependent IAA production in the rhizoplane and potentially within the intercellular spaces of root tissue. Under optimal plant growth promoting conditions in non-sterile soil, the high total microbial titre in the rhizosphere supports a mutualistic relationship between Klebsiella SGM 81 and carnation that potentially extends to the wider rhizosphere microbiota.

     

Revision of the carabid genus <Emphasis Type="Italic">Meroctenus</Emphasis> Gemminger et Harold,with a new status of <Emphasis Type="Italic">Xenodochus</Emphasis> Andrewes (Coleoptera,Carabidae: Harpalini)

Originally described as a monotypical genus with unclear taxonomic position from Sudan, Meroctenus Gemminger et Harold, 1868 is treated as a polytypical genus of the Selenophori genus group with two subgenera: Meroctenus s. str. and Xenodochus Andrewes, 1941, stat. n. (the latter was previously considered a distinct genus). Within Meroctenus, two species are recognized: M. (Meroctenus) crenulatus Chaudoir, 1843 (type species) and M. (M.) mediocris (Andrewes, 1936), comb, n., transferred to Meroctenus s. str. from Xenodochus. A new subspecies M. (M.) crenulatus orientalis subsp. n. is described from Pakistan. Diagnoses of the genus Meroctenus in new interpretation as well as of its two subgenera are discussed, and a taxonomic review of the subgenus Meroctenus s. str. with a key to the species and subspecies is provided. The following synonymy is proposed: Meroctenus Gemminger et Harold, 1868 = Paregaploa Müller, 1947, syn. n.; Meroctenus crenulatus (Chaudoir, 1843) = Egaploa (Paregaploa) conviva Müller, 1947, syn. n. Lectotypes are designated for Ctenomerus crenulatus Chaudoir, 1843 and Xenodus mediocris Andrewes, 1936.     

<Emphasis Type="Italic">Hymenobacter agri</Emphasis> sp. nov., a novel bacterium isolated from soil

A bacterial isolate was recovered from a soil sample collected in Jeollabuk-do Province, South Korea, and subjected to polyphasic taxonomic assessment. Cells of the isolate, designated strain S1-2-1-2-1^T, were observed to be rod-shaped, pink in color, and Gram-stain negative. The strain was able to grow at temperature range from 10 to 30 °C, with an optimum of 25 °C, and growth occurred at pH 6–8. Comparative 16S rRNA gene sequence analysis showed that strain S1-2-1-2-1^T belongs to the genus Hymenobacter, with closely related type strains being Hymenobacter daeguensis 16F3Y-2^T (95.8% similarity), Hymenobacter rubidus DG7B^T (95.8%), Hymenobacter soli PB^T (95.7%), Hymenobacter terrenus MIMtkLc17^T (95.6%), Hymenobacter terrae DG7A^T (95.3%), and Hymenobacter saemangeumensis GSR0100^T (95.2%). The genomic DNA G+C content of strain S1-2-1-2-1^T was 63.0 mol%. The main polar lipid of this strain was phosphatidylethanolamine, the predominant respiratory quinone was menaquinone-7, and the major fatty acids were C_15:0 iso (27.3%), summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) (16.5%), C_15:0 anteiso (15.3%), and C_16:0 (14.7%), supporting the affiliation of this strain with the genus Hymenobacter. The results of this polyphasic analysis allowed for the genotypic and phenotypic differentiation of strain S1-2-1-2-1^T from recognized Hymenobacter species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S1-2-1-2-1^T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter agri sp. nov. is proposed. The type strain is S1-2-1-2-1^T (=KCTC 52739^T?=?JCM 32194^T).     

<Emphasis Type="Italic">Spirosoma luteolum</Emphasis> sp. nov. isolated from water

A novel Gram-negative and rod-shaped bacterial strain, designated as 16F6E^T, was isolated from a water sample. Cells were yellowish in color and catalase- and oxidase-positive. The strain grew at 10–37°C (optimum at 25°C) but not at 4 and 42°C, and pH 5–7 (optimum at pH 7). It showed moderate resistance to gamma-ray irradiation. Comparative phylogenetic analysis showed that strain 16F6E^T belonged to the family Cytophagaceae of the class Cytophagia. Furthermore, this isolate showed relatively low 16S rRNA gene sequence similarities (90.7–93.1%) to the members of the genus Spirosoma. The major fatty acids were summed feature 3 (C_16:1 ω7c/C_16:1 ω6c), C_16:1 ω5c, C_16:0 N alcohol, and C_16:0. The polar lipid profile indicated presence of phosphatidylethanolamine, unknown aminophospholipids, an unknown amino lipid, unknown phospholipids, and unknown polar lipids. The predominant isoprenoid quinone was MK-7. The genomic DNA G+C content of strain 16F6E^T was 56.5 mol%. Phenotypic, phylogenetic, and chemotaxonomic properties indicated that isolate 16F6E^T represents a novel species within the genus Spirosoma, for which the name Spirosoma luteolum sp. nov. is proposed. The type strain is 16F6E^T (=KCTC 52199^T =JCM 31411^T).     

Simultaneous removal of hexavalent chromium and <Emphasis Type="Italic">o</Emphasis>-dichlorobenzene by isolated <Emphasis Type="Italic">Serratia marcescens</Emphasis> ZD-9

Heavy metals–organics mixture pollution is increasingly concerned and simultaneous removal of organic pollutants and heavy metals is becoming significant. In this study, a strain was isolated from the sediment of a tannery effluent outfalls, which can remove o-dichlorobenzene (o-DCB) and Cr(VI) simultaneously. The bacterial isolate was identified as Serratia marcescens by the 16S rRNA gene sequences. The strain removed about 90% of o-DCB and more than 80% of Cr(VI) at the concentration of 1.29 g L^?1 o-DCB and 20 mg L^?1 Cr(VI). In the presence of concomitant pollutant o-DCB, the optimal pH (8.0) and temperature (30 °C) were determined for Cr(VI) removal. Changes of the bacterial cells and intracellular black Cr(III) sediments were observed by the TEM auxiliary analysis. The results of the FTIR spectroscopy analysis indicated that hydroxyl, amide and polysaccharides were involved in the process of Cr(VI) removal.