Influence of soil microbes on Escherichia coli O157:H7 survival in soil rinse and artificial soil.

AIMS: This research investigated the influence of soil microbiota on Escherichia coli O157:H7 survival in soil rinse and artificial soil. Additionally, the influence of selected soil bacteria on E. coli O157:H7 in soil environments was determined. METHODS AND RESULTS: Escherichia coli O157:H7 counts (log CFU per ml or g-1 ) were determined by spread plating: (i) artificial soil amended with soil rinse (filter-sterilized and unfiltered) at 30°C; (ii) unfiltered soil rinse (50 ml) treated with cycloheximide (200 µg ml-1 ), vancomycin (40 µg ml-1 ), heat (80°C, 15 min) and no treatment (control) for 7 days at 30°C and (iii) filtered soil rinse with selected soil bacterial isolates over 7 days. There was a significant difference (P = 0·027) in E. coli O157:H7 counts after 35 days between artificial soils amended with filtered (4·45 ± 0·29) and non-filtered (1·83 ± 0·33) soil rinse. There were significant differences (P < 0·05) in E. coli O157:H7 counts after 3 days of incubation between soil rinse treatments (heat (7·04 ± 0·03), cycloheximide (6·94 ± 0·05), vancomycin (4·26 ± 0·98) and control (5·00 ± 0·93)). Lastly, a significant difference (P < 0·05) in E. coli O157:H7 counts was observed after 3 days of incubation at 30°C in filtered soil rinse when incubated with Paenibacillus alvei versus other soil bacterial isolates evaluated. CONCLUSIONS: Soil microbiota isolated from Florida sandy soil influenced E. coli O157:H7 survival. Specifically, P. alvei reduced E. coli O157:H7 by over 3 log CFU per ml after 3 days of incubation at 30°C in filtered soil rinse. SIGNIFICANCE AND IMPACT OF THE STUDY: This research identified soil bacterial isolates that may reduce E. coli O157:H7 in the soil environment and be used in future biocontrol applications.

Paenibacillus puerhi sp. nov., isolated from the rhizosphere soil of Pu-erh tea plants (Camellia sinensis var. assamica).

An aerobic, Gram-staining-positive, rod-shaped, endospore-forming and motile bacterial strain, designated SJY2T, was isolated from the rhizosphere soil of tea plants (Camellia sinensis var. assamica) collected in the organic tea garden of the Jingmai Pu-erh tea district in Pu'er city, Yunnan, southwest China. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate belonged to the genus Paenibacillus. The closest phylogenetic relative was Paenibacillus filicis DSM 23916T (98.1% similarity). The major fatty acids (> 10% of the total fatty acids) were anteiso-C15:0 and isoC16:0. The major respiratory quinone was MK-7 and the major polar lipid was diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylmonomethylethanolamine. The peptidoglycan contained glutamic acid, serine, alanine and meso-diaminopimelic acid. Genome sequencing revealed a genome size of 6.71 Mbp and a G + C content of 53.1%. Pairwise determined whole genome average nucleotide identity (gANI) values and digital DNA-DNA hybridization (dDDH) values suggested that strain SJY2T represents a new species, for which we propose the name Paenibacillus puerhi sp. nov. with the type strain SJY2T (= CGMCC 1.17156T = KCTC 43242T).

Heavy metals-resistant bacteria (HM-RB): Potential bioremediators of heavy metals-stressed Spinacia oleracea plant.

Microorganism technologies can provide a potential alternative to traditional methods of removing heavy metals to conserve agricultural soils. This study aimed to identify and characterize heavy metals-resistant bacteria (HM-RB) isolated from industry-affected soil and their desired impact as bioremediators of heavy metals-stressed spinach plants. Three of 135 isolates were selected based on a high level of resistance to heavy metals. Based on morphological and biochemical characteristics, the selected isolates were identified as Bacillus subtilis subsp. spizizenii DSM 15029 T DSM (MA3), Paenibacillus jamilae DSM 13815 T DSM (LA22), or Pseudomonas aeruginosa DSM 1117 DSM (SN36). Experiments were implemented to investigate the three isolated HM-RB ability on improving attributes of growth, physio-biochemistry, and components of the antioxidant defense system of spinach plant exposed to the stress of cadmium (Cd2+; 2 mM), lead (Pb2+; 2 mM) or 2 mM Cd2++2 mM Pb2+. Compared to control, Cd2+ or Pb2+ stress markedly lowered plant fresh and dry weights, leaf contents of chlorophylls and carotenoids, rates of transpiration (Tr), net photosynthesis (Pn) and stomatal conductance (gs), relative water content (RWC), and membrane stability index (MSI). In contrast, contents of α.tochopherol (α.TOC), ascorbic acid (AsA), glutathione (GSH), proline, soluble sugars, Cd2+, and Pb2+, as well as activities of enzymatic and non-enzymatic antioxidants were markedly elevated. The application of HM-RB promoted the tolerance to heavy metal stress in spinach plants by improving Tr, Pn, gs, RWC, and MSI, while activities of enzymatic and non-enzymatic antioxidants were suppressed. These results reflected positively in promoting plant growth under heavy metal stress. Therefore, the application of HM-RB as potential bioremediators may be a promising strategy for promoting plant growth and productivity under heavy metal stress.

Paenibacillus seodonensis sp. nov., isolated from a plant of the genus Campanula.

Strain DCT-19T, representing a Gram-stain-positive, rodshaped, aerobic bacterium, was isolated from a native plant belonging to the genus Campanula on Dokdo, the Republic of Korea. Comparative analysis of the 16S rRNA gene sequence showed that this strain was closely related to Paenibacillus amylolyticus NRRL NRS-290T (98.6%, 16S rRNA gene sequence similarity), Paenibacillus tundrae A10bT (98.1%), and Paenibacillus xylanexedens NRRL B-51090T (97.6%). DNADNA hybridization indicated that this strain had relatively low levels of DNA-DNA relatedness with P. amylolyticus NRRL NRS-290T (30.0%), P. xylanexedens NRRL B-51090T (29.0%), and P. tundrae A10bT (24.5%). Additionally, the genomic DNA G + C content of DCT-19T was 44.8%. The isolated strain grew at pH 6.0-8.0 (optimum, pH 7.0), 0-4% (w/v) NaCl (optimum, 0%), and a temperature of 15-45°C (optimum 25-30°C). The sole respiratory quinone in the strain was menaquinone-7, and the predominant fatty acids were C15:0 anteiso, C16:0 iso, and C16:0. In addition, the major polar lipids were diphosphatidylglycerol and phosphatidylethanolamine. Based on its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain DCT-19T is proposed as a novel species in the genus Paenibacillus, for which the name Paenibacillus seodonensis sp. nov. is proposed (=KCTC 43009T =LMG 30888T). The type strain of Paenibacillus seodonensis is DCT-19T.

Paenibacillus albilobatus sp. nov., isolated from acidic soil on Jeju Island.

A rod-shaped, white color colony with lobate architectures, strain h2T was isolated from a moderately acidic soil on Jeju Island, Republic of Korea. Comparative analysis of the 16S rRNA gene sequence showed that the strain h2T is closely related to Paenibacillus relictisesami DSM 25385T (97.4%, 16S rRNA gene sequence similarity), Paenibacillus azoreducens KACC 11244T (97.2%), and Paenibacillus cookii LMG 18419T (97.0%). DNA-DNA hybridization indicated that the strain h2T has relatively low levels of DNA-DNA relatedness with respect to P. relictisesami DSM 25385T (10.2%) and P. azoreducens KACC 11244T (13.7%). Additionally, the genomic DNA G + C content of h2T is 51.5 mol%. The isolated strain grew at pH 4.0-9.0 (optimum, pH 6.0-7.0) and 0-5% (w/v) NaCl (optimum, 0%) and a temperature of 15-45°C (optimum 35°C). The quinones in the strain are MK-6 and MK-7, and the predominant fatty acid is C15:0 anteiso (32.1%) followed by C17:0 anteiso (26.5%), and C16:0 iso (21.0%). Based on its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain h2T is proposed as a novel species in the genus Paenibacillus, for which the name Paenibacillus albilobatus sp. nov. is proposed (= KCCM 43269T = JCM 32395T = LMG 30408T). The type strain of Paenibacillus albilobatus is h2T.

Plant growth-promoting bacteria elevate the nutritional and functional properties of black cumin and flaxseed fixed oil.

BACKGROUND: In order to study the influence of plant growth-promoting bacteria (PGPB) belonging to Streptomyces sp., Paenibacillus sp., and Hymenobacter sp. on fixed oil content of flaxseed and black cumin, 2-year field experiments were conducted. PGPB was applied during seedtime of plants. The extraction of oil from seeds was performed using supercritical CO2 . RESULTS: The addition of PGPB significantly increases the content of C18:1 (from 16.06 ± 0.03% to 16.97 ± 0.03%) and C18:3 (from 42.97 ± 0.2% to 45.42 ± 0.5%) in flaxseed oil and C18:2 (from 52.68 ± 0.50% to 57.11 ± 0.40%) and C20:2 (from 4.34 ± 0.02% to 4.54 ± 0.03%) in black cumin seed oil. The contents of total polyphenols, flavonoids, and carotenoids, as well as antioxidant activity measured by ferric-reducing ability of plasma assay, were found to be greater in the oil from the seeds of plants treated with the PGPB, compared with the respective non-treated samples. CONCLUSION: The use of PGPB enhances plant nutritive properties; these represent a great source for obtaining valuable functional food ingredients. © 2017 Society of Chemical Industry.

Effects of plant- and animal-based high-fat diets on lipid storage and distribution in environmental bacteria-colonized gnotobiotic mice.

Different edible oils such as lard and soybean oil have been reported to interact with the gut microbiota, affecting host lipid metabolism. However, whether bacteria derived from the environment influence host lipid metabolism remains unclear. This study aimed to clarify the roles of environmental bacteria in host lipid storage and distribution with various edible oils. Gnotobiotic C57BL/6JNarl mice were inoculated with Lysinibacillus xylanilyticus and Paenibacillus azoreducens and then fed either a normal diet (LabDiet 5010, control group) or a diet containing 60% lard (L-group) or soybean oil (S-group) for 18 months. Interestingly, the S-group accumulated massive amounts of white adipose tissue compared to the L- and control groups, while the L-group displayed more hepatic steatosis and fatty droplets than the other groups. The expression of fatty acid synthase (FAS), hydroxymethylglutaryl-coenzyme A reductase (HMGCR), sterol regulatory element-binding protein 2 (SREBP2), and peroxisome proliferator-activated receptor gamma (PPARγ) in the livers of the L-group were markedly elevated compared to the S-group. FAS and PPARγ protein levels were also markedly elevated. However, there were no differences in the expression of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-α between the groups. Our results suggest that environmental bacteria may affect host hepatic inflammation and lipid distribution in the presence of high-fat diets, with different effects depending on the fat type consumed.

Paenibacillus aquistagni sp. nov., isolated from an artificial lake accumulating industrial wastewater.

Strain 11T was isolated from water of an artificial lake accumulating industrial wastewater on the outskirts of Celje, Slovenia. Phenotypic characterisation showed strain 11T to be a Gram-stain positive, spore forming bacterium. The 16S rRNA gene sequence identified strain 11T as a member of the genus Paenibacillus, closely related to Paenibacillus alvei (96.2%). Genomic similarity with P. alvei 29T was 73.1% (gANI), 70.2% (ANIb), 86.7% (ANIm) and 21.7 ± 2.3% (GGDC). The DNA G+C content of strain 11T was determined to be 47.5%. The predominant menaquinone of strain 11T was identified as MK-7 and the major fatty acid as anteiso-C15:0. The peptidoglycan was found to contain meso-diaminopimelic acid. In contrast to its close relatives P. alvei DSM 29T, Paenibacillus apiarius DSM 5581T and Paenibacillus profundus NRIC 0885T, strain 11T was found to be able to ferment D-fructose, D-mannose and D-xylose. A draft genome of strain 11T contains a cluster of genes associated with type IV pilin synthesis usually found in clostridia, and only sporadically in other Gram-positive bacteria. Genotypic, chemotaxonomic, physiological and biochemical characteristics of strain 11T presented in this study support the creation of a novel species within the genus Paenibacillus, for which the name Paenibacillus aquistagni sp. nov. is proposed, with strain 11T (=ZIM B1027T =LMG 29561T =CCM 8679T ) as the type strain.

Toxicity and biofilm-based selection for methyl tert-butyl ether bioremediation technology.

Extractive membrane biofilm reactor (EMBFR) technology offers productive solutions for volatile and semi-volatile compound removal from water bodies. In this study, the bacterial strains Paenibacillus etheri SH7T (CECT 8558), Agrobacterium sp. MS2 (CECT 8557) and Rhodococcus ruber strains A5 (CECT 8556), EE6 (CECT 8612) and EE1 (CECT 8555), previously isolated from fuel-contaminated sites, were tested for adherence on tubular semipermeable membranes in laboratory-scale systems designed for methyl tert-butyl ether (MTBE) bioremediation. Biofilm formation on the membrane surface was evaluated through observation by field-emission scanning electron microscope (FESEM) as well as the acute toxicity (as EC50) of the bacterial growth media. Moreover, extracellular polymeric substance (EPS) production for each strain under different MTBE concentrations was measured. Strains A5 and MS2 were biofilm producers and their adherence increased when the MTBE flowed through the inner tubular semipermeable membrane. No biofilm was formed by Paenibacillus etheri SH7T, nevertheless, the latter and strain MS2 exhibited the lowest toxicity after growth on the EMBFR. The results obtained from FESEM and toxicity analysis demonstrate that bacterial strains R. ruber EE6, A5, P. etheri SH7T and Agrobacterium sp. MS2 could be excellent candidates to be used as selective inocula in EMBFR technology for MTBE bioremediation.

The B1 Protein Guides the Biosynthesis of a Lasso Peptide.

Lasso peptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) with a unique lariat knot-like fold that endows them with extraordinary stability and biologically relevant activity. However, the biosynthetic mechanism of these fascinating molecules remains largely speculative. Generally, two enzymes (B for processing and C for cyclization) are required to assemble the unusual knot-like structure. Several subsets of lasso peptide gene clusters feature a "split" B protein on separate open reading frames (B1 and B2), suggesting distinct functions for the B protein in lasso peptide biosynthesis. Herein, we provide new insights into the role of the RiPP recognition element (RRE) PadeB1, characterizing its capacity to bind the paeninodin leader peptide and deliver its peptide substrate to PadeB2 for processing.

Paenibacillus salinicaeni sp. nov., isolated from saline silt sample.

A novel facultatively anaerobic bacterium, designated strain LAM0A28(T), was isolated from a saline silt sample collected from the Chinese Sea of Death located in Suining city, Sichuan province, China. Cells of strain LAM0A28(T) were observed to be Gram-stain positive, motile, endospore-forming and straight-rod shaped. Strain LAM0A28(T) was found to be able to grow at 15-45 °C (optimum: 30-35 °C), pH 5.0-10.0 (optimum: 7.5) and 0-5 % NaCl (w/v) (optimum: 0.5 %). The 16S rRNA gene sequence similarity analysis showed that strain LAM0A28(T) is closely related to Paenibacillus jilunlii DSM 23019(T) (97.5 %) and Paenibacillus graminis DSM 15220(T) (97.2 %). The DNA-DNA hybridization values between the isolate and P. jilunlii DSM 23019(T), P. graminis DSM 15220(T) were 30.2 ± 1.6 % and 44.7 ± 2.1 %, respectively. The DNA G+C content was found to be 51.2 mol% as determined by the T m method. The major cellular fatty acids were identified as anteiso-C15:0, C16:0, iso-C16:0 and C14:0. The major isoprenoid quinone was identified as MK-7. The cell wall peptidoglycan was found to contain meso-diaminopimelic acid. The major polar lipids were found to be diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two aminophospholipids and six unidentified lipids. Based on the phylogenetic, phenotypic and chemotaxonomic characteristics, strain LAM0A28(T) is concluded to represent a novel species within the genus Paenibacillus, for which the name Paenibacillus salinicaeni sp. nov. is proposed. The type strain is LAM0A28(T) (=ACCC 00741(T) = JCM 30850(T)).

Paenibacillus herberti sp. nov., an endophyte isolated from Herbertus sendtneri.

Strain R33(T), an endophyte recovered from Herbertus sendtneri, was identified as representing a novel species of the genus Paenibacillus by using a polyphasic taxonomic approach. The novel strain was observed to be a Gram-stain positive, aerobic, rod-shaped, motile and endospore-forming bacterium. The major polar lipids of strain R33(T) were identified as diphosphatidylglycerol, phosphatidylethanolamine, along with lesser amounts of phosphatidylglycerol, three unidentified aminophospholipids, two unidentified phospholipids and two unidentified lipids. The predominant isoprenoid quinone was identified as MK-7. The major fatty acids (>8.0 %) were found to be anteiso-C15:0 (40.0 %), C16:1 ω11c (9.4 %), C16:1 ω7c alcohol (8.5 %) and C16:0 (8.2 %). The diamino acid found in the cell-wall peptidoglycan was meso-diaminopimelic acid. The G+C content of genomic DNA was determined to be 56.9 mol%. The 16S rRNA gene sequence similarities of strain R33(T) to other Paenibacillus species ranged from 91.6 to 97.2 %, with high similarities to Paenibacillus humicus PC-147(T) and Paenibacillus pasadenensis SAFN-007(T). The phylogenetic analyses based on 16S rRNA gene sequences and the partial rpoB gene confirmed that strain R33(T) belongs to the genus Paenibacillus. However, strain R33(T) shows differential molecular characteristics compared to other related Paenibacillus species based on 16S rDNA-RFLP analyses; the DNA-DNA relatedness values between strain R33(T) and P. humicus PC-147(T), and that between strain R33(T) and P. pasadenensis SAFN-007(T), were 35.0 ± 2.0 and 41.4 ± 0.9 %, respectively. Based on its phenotypic, chemotaxonomic and phylogenetic properties, strain R33(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus herberti is proposed (type strain R33(T) = CGMCC 1.15042(T) = DSM 29849(T)).

Biocontrol of Fusarium wilt disease in tomato by Paenibacillus ehimensis KWN38.

This study was conducted to investigate biocontrol potential of Paenibacillus ehimensis KWN38 against Fusarium oxysporum f.sp. lycopersici causing Fusarium wilt disease in tomato. Our result showed that P. ehimensis KWN38 produced extracellular organic compounds and crude enzyme to inhibit F. oxysporum f.sp. lycopersici conidial germination in in vitro assays. Tomato seedlings were treated with water (W), grass medium (G), G with P. ehimensis KWN38 inoculation (GP) and G along with synthetic fungicide (GSf). Disease symptoms were was first observed in G and W at 12 days after infection (DAI) while symptoms were noticeable in the GP and GSf treatments at 20 and 24 DAI, respectively. Tomato plants treated with P. ehimensis KWN38 or fungicide significantly reduced Fusarium wilt disease incidence and severity as compared to control tomato plants treated with water and grass medium. The similar results were also found in the root mortality of tomato plants. At 25 DAI, most plants in control treatments (W and G) wilted and the brown vascular systems of infected plants was clearly differentiable from normal green vascular system of healthy plants from GP and GSf. Plants in the GP showed higher fresh and dry weights of both root and shoots than those in W and G treatments. Leaf peroxidase and polyphenol oxidase activities of tomato plants in G and W were higher than those in GP and GSf. Root enzyme activities showed a similar pattern but the values were higher than leaf enzyme. The results clearly demonstrated that P. ehimensis KWN38 may be considered as biocontrol agent of Fusarium wilt disease in tomato.

Paenibacillus nicotianae sp. nov., isolated from a tobacco sample.

A Gram-stain positive, facultative anaerobic endospore-forming bacterium, designated strain YIM h-19(T), was isolated from a tobacco sample. Cells were observed to be motile rods by means of peritrichous flagella and colonies were observed to be convex, yellow, circular and showed catalase-positive and oxidase-negative reactions. Strain YIM h-19(T) was able to grow at 4-45 °C, pH 6.0-8.0 and 0-3 % NaCl (w/v). The predominant respiratory quinone was identified as MK-7. Major fatty acids were identified as anteiso-C15:0, anteiso-C17:0 and C16:0. The polar lipids were found to be phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and two unidentified polar lipids. The genomic DNA G+C content was determined to be 54 mol%. 16S rRNA gene sequence analysis showed the strain YIM h-19(T) was most closely related to Paenibacillus hordei RH-N24(T) and Paenibacillus hunanensis FeL05(T) with similarities of 98.30 and 94.64 % respectively. However, DNA-DNA hybridization data indicated that the isolate represented a novel genomic species with the genus Paenibacillus. All data from genotypic and phenotypic analyses support the conclusion that strain YIM h-19(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus nicotianae sp. nov. is proposed. The type strain is YIM h-19(T) (=CGMCC1.12819(T) = NRRL B-59112(T)).

Paenibacillus abyssi sp. nov., isolated from an abyssal sediment sample from the Indian Ocean.

A Gram-positive, rod-shaped bacterium, designated strain SCSIO N0306(T), was isolated from an abyssal sediment sample collected from the Indian Ocean. The isolate was found to grow optimally at 0-2 % (w/v) NaCl, pH 7.0 and 30 °C. Comparative analysis of the 16S rRNA gene sequence showed that the isolate SCSIO N0306(T) belongs phylogenetically to the genus Paenibacillus, and to be most closely related to P. algorifonticola XJ259(T) (with 95.47 % sequence similarity), sharing less than 95.0 % sequence similarity with all other taxa of this genus. Chemotaxonomic analysis revealed MK-7 as the major isoprenoid quinone, the DNA G+C content was determined to be 45.5 mol%, and anteiso-C15:0, C16:0, and iso-C15:0 were identified as the major fatty acids. On the basis of this polyphasic taxonomic data, isolate SCSIO N0306(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus abyssi sp. nov. is proposed. The type strain is SCSIO N0306(T) (= DSM 26238(T) = CGMCC 1.12987(T)).

Inactivation of Escherichia coli O157:H7 on stainless steel upon exposure to Paenibacillus polymyxa biofilms.

We investigated the potential use of biofilm formed by a competitive-exclusion (CE) microorganism to inactivate Escherichia coli O157:H7 on a stainless steel surface. Five microorganisms showing inhibitory activities against E. coli O157:H7 were isolated from vegetable seeds and sprouts. The microorganism with the greatest antimicrobial activity was identified as Paenibacillus polymyxa (strain T5). In tryptic soy broth (TSB), strain T5 reached a higher population at 25 °C than at 12 or 37 °C without losing inhibitory activity against E. coli O157:H7. When P. polymyxa (6 log CFU/mL) was co-cultured with E. coli O157:H7 (2, 3, 4, or 5 log CFU/mL) in TSB at 25 °C, the number of E. coli O157:H7 decreased significantly within 24h. P. polymyxa formed a biofilm on stainless steel coupons (SSCs) in TSB at 25 °C within 24h, and cells in biofilms, compared to attached cells without biofilm formation, showed significantly increased resistance to a dry environment (43% relative humidity [RH]). With the exception of an inoculum of 4 log CFU/coupon at 100% RH, upon exposure to biofilm formed by P. polymyxa on SSCs, populations of E. coli O157:H7 (2, 4, or 6 log CFU/coupon) were significantly reduced within 48 h. Most notably, when E. coli O157:H7 at 2 log CFU/coupon was applied to SSCs on which P. polymyxa biofilm had formed, it was inactivated within 1h, regardless of RH. These results will be useful when developing strategies using biofilms produced by competitive exclusion microorganisms to inactivate foodborne pathogens in food processing environments.

Identification and characterization of a highly motile and antibiotic refractory subpopulation involved in the expansion of swarming colonies of Paenibacillus vortex.

Bacteria often use sophisticated cooperative behaviours, such as the development of complex colonies, elaborate biofilms and advanced dispersal strategies, to cope with the harsh and variable conditions of natural habitats, including the presence of antibiotics. Paenibacillus vortex uses swarming motility and cell-to-cell communication to form complex, structured colonies. The modular organization of P. vortex colony has been found to facilitate its dispersal on agar surfaces. The current study reveals that the complex structure of the colony is generated by the coexistence and transition between two morphotypes--'builders' and 'explorers'--with distinct functions in colony formation. Here, we focused on the explorers, which are highly motile and spearhead colonial expansion. Explorers are characterized by high expression levels of flagellar genes, such as flagellin (hag), motA, fliI, flgK and sigD, hyperflagellation, decrease in ATP (adenosine-5'-triphosphate) levels, and increased resistance to antibiotics. Their tolerance to many antibiotics gives them the advantage of translocation through antibiotics-containing areas. This work gives new insights on the importance of cell differentiation and task distribution in colony morphogenesis and adaptation to antibiotics.

Inhibitory activity of Paenibacillus polymyxa on the biofilm formation of Cronobacter spp. on stainless steel surfaces.

The objective of this study was to control the survival or biofilm formation of Cronobacter spp. on stainless steel surfaces using Paenibacillus polymyxa. The antibacterial activity of a cell-free culture supernatant (CFCS) of P. polymyxa against Cronobacter spp. was found to vary with P. polymyxa incubation time. Maximum activity occurred when P. polymyxa was incubated at 25 or 30 °C for 96 h. When the CFCS was introduced to Cronobacter spp. adhered to stainless steel strips at 25 °C for up to 72 h, the CFCS successfully inhibited Cronobacter biofilm formation. Additionally, stainless steel surfaces with a preformed P. polymyxa biofilm were exposed to Cronobacter spp. suspensions in PBS or 0.1% peptone water at 3, 5, or 7 log CFU/mL to facilitate its attachment. The Cronobacter population significantly decreased on this surface, regardless of inoculum level or carrier, when the P. polymyxa biofilm was present. However, the microbial population decreased within 6 h and remained unchanged thereafter when the surface was immersed in an inoculum suspended in 0.1% peptone water at 5 or 7 log CFU/mL. These results indicate that P. polymyxa is able to use a promising candidate competitive-exclusion microorganism to control Cronobacter spp.

Paenibacillus thermophilus sp. nov., a novel bacterium isolated from a sediment of hot spring in Fujian province, China.

A Gram-positive, thermophilic, strictly aerobic bacterium, designated WP-1(T), was isolated from a sediment sample from a hot spring in Fujian province of China and subjected to a polyphasic taxonomic study. Cells of strain WP-1(T) were rods (~0.6-0.8 × 2.5-3.5 µm) and motile by means of peritrichous flagella. Endospores were ellipsoidal in terminal or subterminal positions. Strain WP-1(T) grew at 37-60 °C (optimum 42-45 °C), 0-3 % NaCl (optimum 1 %, w/v) and pH 3.0-9.0 (optimum pH 6.5-7.0). The predominant menaquinone was MK-7. The major fatty acids were anteiso-C(15:0), iso-C(16:0), C(16:0) and anteiso-C(17:0). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, two glycolipids, two unidentified phospholipids and two unknown polar lipids. The cell-wall peptidoglycan contained meso-diaminopimelic acid (meso-DAP). The G + C content of the genomic DNA was 52.5 %. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain WP-1(T) is a member of the genus Paenibacillus and exhibited sequence similarity of 99.3 % to Paenibacillus macerans DSM 24(T) and both strains represented a separate lineage from all other Paenibacillus species. However, the level of DNA-DNA relatedness between strain WP-1(T) and P. macerans DSM 24(T) was 34.0 ± 4.7 %. On the basis of phylogenetic, physiological and chemotaxonomic analysis data, strain WP-1(T) is considered to represent as a novel species of the genus Paenibacillus, for which the name Paenibacillus thermophilus sp. nov., is proposed, with the type strain WP-1(T) (=DSM 24746(T) = JCM 17693(T) = CCTCC AB 2011115(T)).

[Diversity of antagonistic bacteria isolated from rhizosphere of several cash crops].

By adopting antimicrobial spectrum test, BOXAIR-PCR, physiological and biochemical, and 16S rDNA sequencing analysis, this paper analyzed the diversity of 55 antagonistic bacterial strains isolated from the rhizosphere of 10 cash crops. There was a high diversity of the antagonism of the strains. Based on BOXAIR-PCR, all the strains were clustered into 7 groups at the similarity level of 72.1%, and divided into 25 groups at the similarity level of 85.0%. All the strains belonged to Bacillus, Paenibacillus, Brevibacillus, Pseudomonas and Alcaligenes, respectively. The antagonistic bacteria isolated from the rhizosphere had high genetic diversity and high diversity in antagonistic activity.