[Effects of three Bacillus strains on growth promoting and rhizosphere soil microflora of tomato.] / 3æ ªèŠ½å­¢æ†èŒå¯¹ç•ªèŒ„çš„ä¿ƒç”Ÿä½œç”¨åŠå¯¹ç•ªèŒ„æ ¹åŸŸå¾®ç”Ÿç‰©çš„å½±å“.

The effects of Bacillus Bs10, Ba12 and Bl10 on tomato growth and soil rhizosphere microorganisms were determined by Petri dish germination test and pot experiments. The results showed that Bs10, Ba12 and Bl10 exhibited remarkable promoting effect on the length of hypocotyl and radical, as well as the growth of plants. The length, surface area and volume of tomato roots increased significantly after treatment with Bacillus stains, the numbers and proportions of soil bacteria also increased markedly, while those of soil fungi decreased. The numbers of the dominant bacteria and fungi were changed, withBacillus methylotrophicus being much higher in root zone soil, surface soil and neouchi, while the plant pathogens Fusarium solani and Fusarium oxysporum decreased significantly in root zone soil and root surface soil. These results suggested that the addition of Bs10, Ba12 and Bl10 could improve the micro-ecosystem of the root domain of tomato, which might play an important role in growth promoting and disease prevention on tomato plants.

[Effects and mechanism of two Streptomyces strains on promoting plant growth and increasing grain yield of maize]. / ä¸¤æ ªé“¾éœ‰èŒå¯¹çŽ‰ç±³çš„ä¿ƒç”Ÿå¢žäº§ä½œç”¨åŠæœºç†.

This paper was mainly to explore the effects of two Streptomyces strains (S. roche D74 and S. pactum Act12) and their mixed actinomycetes agent on maize growth. Petri dish germination test, sand culture trial and plot trial were performed to determine the biological properties, leaf inducible enzyme activities, photosynthesis, ear characteristics, grain yield and quality of maize after seed soaking with acellular culture filtrate of D74 or Act 12 and seed coating with the mixed actinomycetes agent of two Streptomyces stains. The result showed that the seed soaking treatment significantly contributed to hypocotyls, radical and seedling growth, and increased the leaf inducible enzyme activities of maize seedlings. The 1000-fold dilution of D74 improved hypocotyl length, radicle length, and fibrous root number by 43.4%, 26.4%, and 100.7% (P<0.05), respectively, whereas the undiluted solution of D74 improved leaf polyphenol oxidase (PPO) activity by 40.2% (P<0.05). The 1000-fold dilution of Act12 improved hypocotyl length, radicle length, and fibrous root number by 36.3%, 36.3%, and 117.5% (P<0.05), the total fresh mass and root fresh mass by 31.1% and 36.6%, respectively (P<0.05). The 10-fold and 1000-fold dilutions of Act12 improved leaf PPO activity by 38.1% and 39.5%, respectively (P<0.05). The seed coating treatment showed the following significant effects, compared with the control: 1) Improving the root development. 2) Enhancing the leaf photosynthesis. 3) Improving the ear characteristics and grain yield. 4) Promoteing the grain filling. 5) Improving the leaf inducible enzyme activities. The results indicated that seed coating with the mixed actinomycetes agent of two Streptomyces strains could significantly affect the biological characteristics, photosynthesis and biochemical metabolism of maize seedlings, stimulate root development, promote plant growth, and improve grain yield of maize.

α-Glucosidase inhibitors and phytotoxins from Streptomyces xanthophaeus.

Twenty-four metabolites 1-24 were isolated from the fermentation broth of Streptomyces xanthophaeus. Their structures were elucidated on the basis of spectroscopic analysis and by comparison of their NMR data with literature data reported. Daidzein (1), genistein (2) and gliricidin (3) inhibited α-glucosidase in vitro with IC50 values of 174.2, 36.1 and 47.4 µM, respectively, more potent than the positive control, acarbose. Docking study revealed that the amino acid residue Thr 215 is the essential binding site for active ligands 2. In addition, the phytotoxic effects of all compounds were assayed on radish seedlings, five of which, 3, 8, 13, 15 and 18, inhibited the growth of radish (Raphanus sativus) seedlings with inhibitory rates of >60% at a concentration of 100 ppm, which was comparable or superior to the positive control glyphosate. This is the first report of the phytotoxicity of the compounds.

Gabosines P and Q, new carbasugars from Streptomyces sp. and their α-glucosidase inhibitory activity.

Two new polyoxygenated cyclohexenone 'ketocarbasugars', named gabosines P and Q (1 and 2), were isolated from the culture of the actinomycete Streptomycetes strain no. 8, along with two known cyclic dipeptides. The structures and absolute configurations of the new metabolites were determined by spectroscopic data (1D- and 2D-NMR, HR-ESI-MS, and IR), chemical transformation, and electronic circular dichroism (ECD). These compounds were evaluated for α-glucosidase inhibitory activity in vitro. Only compound 1 exhibited IC50 values of 9.07µM, with potency higher than that of the control acarbose. Molecular docking studies revealed the existence of hydrogen bonding and hydrophobic interaction between the enzyme and gabosine P. The results will be useful in designing new anti-diabetes control agents.

Oligotrophy is Helpful for the Isolation of Bioactive Actinomycetes.

It is necessary to develop new methods for the isolation of unknown actinomycetes from soils. To evaluate the effects of oligotrophic medium on the isolation of soil actinomycetes and develop a new isolation method, the Gause's synthetic medium was diluted to one tenth the recommended concentration in the present study. Soil dilution plate technique was used to isolate actinomycetes from the soil samples. Oligotrophy decreased actinomycete and streptomycete counts, as well as the number of antagonistic actinomycete species. Oligotrophy also decreased the number of actinomycete species in five samples. Some actinomycete species were cultured only on the oligotrophic medium, whereas other species could not be cultured. Oligotrophy decreased actinomycete counts more significantly for soils with organic matter content >40 g/kg. We used 16S rRNA sequence analysis to identify 22 actinomycete species that were only cultured on the oligotrophic medium. Oligotrophic medium was helpful for the isolation of Streptomyces spp., Micromonospora spp. and Streptosporangium spp. Slightly more than 80 % of the identified actinomycete species were biologically active. Therefore, we could draw a conclusion that oligotrophic medium could be helpful for the discovery of new antibiotic producers and the exploitation and utilization of new, biologically active compounds.

Paenibacillus quercus sp. nov., isolated from rhizosphere of Quercus aliena var. acuteserrata.

A Gram-positive, spore-forming, rod-shaped and motile bacterium, designated strain 1-25(T), was isolated from the rhizosphere of Quercus aliena var. acuteserrata in Taibai Mountain, Shaanxi Province, China. 16S rRNA gene sequence analysis showed that strain 1-25(T) belongs to the genus Paenibacillus. Strain 1-25(T) was found to be closely related to Paenibacillus harenae and Paenibacillus castaneae with 96.0 and 95.9 % 16S rRNA gene sequence similarities, respectively. The strain was observed to grow optimally at 28 °C and pH 7.5. The major isoprenoid quinone was found to be menaquinone-7. The dominant cellular fatty acids were identified as anteiso-C15:0 and iso-C15:0. The diagnostic diamino acid in the cell-wall peptidoglycan was found to be meso-diaminopimelic acid. The DNA G+C content was determined to be 41.6 mol%. On the basis of phenotypic characteristics and molecular properties, strain 1-25(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus quercus sp. nov. is proposed. The type strain is 1-25(T) (=CCTCC AB2013265(T) = KCTC 33194(T)).

[Microecological mechanisms of red-leaf disease occurrence in Salvia miltiorrhiza Bge].

A comparative study was made on the nutrient content in rhizosphere soil and the microflora in rhizosphere soil and on rhizoplane of healthy and red-leaf diseased Salvia miltiorrhiza plants, aimed to approach the microecological mechanisms of red-leaf disease occurrence in S. miltiorrhiza. The N, P, K, and Mn contents in the diseased plant leaves were significantly lower than those in the healthy plant leaves (P < 0.05). No significant difference was observed in the available P content in the rhizosphere soils of diseased and healthy S. miltiorrhiza, but the available N and K contents were significantly higher (P < 0.05) in the rhizosphere soil of diseased S. miltiorrhiza. These results indicated that the red-leaf disease occurrence in S. miltiorrhiza was related to plant P deficiency, but the lack of P in the plants was not caused by the insufficient soil P supply. As compared with those in healthy S. miltiorrhiza rhizosphere, the bacterial number in diseased S. miltiorrhiza rhizosphere soil decreased by 41.3% , while the fungal and actinomycetes numbers increased by 156.6% and 189.5% (P < 0.05), respectively. Similar variations in the numbers of bacteria, fungi, and actinomycetes were observed on diseased S. miltiorrhiza rhizoplane. In the rhizosphere soil and on the rhizoplane of diseased S. miltiorrhiza, the predominant microbial species that might be harmful included six fungi (Fusarium solani, Myrothecium roridum, F. tricinctum, Aspergillus calidoustus, F. oxysporum, and Dothideomycetes sp.), four actinomycetes (Streptomyces lateritius, Lentzea waywayandensis, S. stelliscabiei and S. collinus), and two bacteria (Bacillus aryabhattai and Piscinibacter aquaticus). These predominant soil microbes likely caused plant P deficiency via negatively affecting the growth of roots and their absorption of soil nutrients. It was suggested that the red-leaf disease occurrence in S. miltiorrhiza was closely related to the plant P deficiency caused by the abnormality of soil microflora in the rhizosphere soil and on the rhizoplane of S. miltiorrhiza.

[Identification of two Fusarium isolates and their crude toxin allelopathic effect on Cucumis melo seedlings].

Eight fungi isolates were obtained from Fusarium-infected Cucumis melo (melon) plants and their rhizosphere soils. Taking melon cultivar 'Xitian 1' as test material, the re-inoculation and seed germination experiments were conducted to investigate the pathogenicity and growth inhibition effect of these fungi isolates on melon. Through the determination of the induced enzyme activities, resistant substance contents, and cell membrane permeability of potted melon roots, the allelopathic effect of the crude toxins of two harmful fungi was studied, and according to the morphological characteristics and Internal Transcribed Spacer (ITS) sequencing, the two harmful fungi were identified. The crude toxins of the two harmful fungi TF and HF had strong inhibition effects on the germination and growth of the melon seeds. The MDA and soluble protein contents and the cell membrane permeability of the 'Xitian 1' seedlings roots all increased, among which, the MDA content and cell membrane permeability increased by 108.6% and 40.6%, respectively when treated with the stock solution of TF toxin, compared with the control. The crude toxins of the two harmful fungi improved the induced enzyme activities of the melon roots, with the increment of the PAL and POD activities under the treatment of 10-fold dilution of TF crude toxin increased by 25.6% and 23.2%, respectively. When treated with the stock solution of HF toxin, the PAL activity significantly increased by 30.0%. The two harmful fungi TF and HF were primarily identified as Fusarium equisti and F. proliferatum, respectively. This study showed that the two Fusarium isolates could not infect melon via re-inoculation, but could negatively affect the melon's normal growth and normal physiological and biochemical metabolism via toxins excretion, and in the meantime, improve the root protective enzyme activities, with the effects of both benefit and harmfulness on melon plants. The allelopathic hazard of the crude toxins of the isolates could be one of the main causes of continuous cropping obstacle of melon.

Bioactive alkaloids produced by Pseudomonas brassicacearum subsp. Neoaurantiaca, an endophytic bacterium from Salvia miltiorrhiza.

Eleven compounds were isolated from the culture of an endophytic bacterium Pseudomonas brassicacearum subsp. Neoaurantiaca in Salvia miltiorrhiza Bunge. Their structures were elucidated by spectroscopic methods as cyclo-(Gly-L-Ala) (1), cyclo-(L-Ala-L-Ala) (2), cyclo-(L-Pro-Gly) (3), cyclo-(L-Pro-L-Ser) (4), cyclo-(L-Ala-trans-4-hydroxy-L-Pro) (5), cyclo-(L-Val-L-Pro) (6), cyclo-(Gly-L-Tyr) (7), cyclo-(L-Ala-L-Tyr) (8), cyclo-(L-Tyr-trans-4-hydroxy-L-Pro) (9), 3-methylhydantoin (10) and 2-piperidinone (11). All these compounds were isolated from this bacterium for the first time. The brine shrimp lethality, antifungal and antibacterial activities of these compounds were evaluated. The results indicated that some cyclodipeptides may play an important role in plant-bacteria interactions.

[Effects of actinomycetes agent on ginseng growth and rhizosphere soil microflora].

Taking the ginseng in Xiao Xing' an Mountains of Northeast China as test object, this paper studied the effects of applying Streptomyces pactum (Act12) on ginseng growth and on the soil microflora in root zone and root surface. After treated with Act12, the yield and quality of ginseng' s medicinal part improved, the induced enzyme activities in leaves and the root activity increased, and the numbers and proportions of soil bacteria and actinomycetes increased significantly while those of soil fungi decreased. Compared with the control, the soil microflora in treatment Act12 changed. The numbers of the dominant bacteria Pseudomonas fluorescens, Pseudomonas koreensis, and Microbacterium oxydans were much higher in root zone soil and root surface soil, and the pathogen Plectosphaerella cucumerina decreased in root zone soil and disappeared in root surface soil. These results suggested that the addition of Act12 could improve the soil microflora, enhance the resistance and root activity of ginseng plant, and increase the ginseng yield and its quality.

Enteractinococcus coprophilus gen. nov., sp. nov., of the family Micrococcaceae, isolated from Panthera tigris amoyensis faeces, and transfer of Yaniella fodinae Dhanjal et al. 2011 to the genus Enteractinococcus as Enteractinococcus fodinae comb. nov.

A novel actinobacterium, designated strain YIM 100590(T), was isolated from Panthera tigris amoyensis faeces collected from Yunnan Wild Animal Park in Yunnan province, south-west China. Phylogenetic analysis based on 16S rRNA gene sequence data showed that strain YIM 100590(T) is a member of the family Micrococcaceae. Cells were coccoid to oval (0.7-1.5 µm in diameter) occurring singly or in clusters. Growth was observed at 10-37 °C (optimum 28 °C) and at pH 7.0-11.0 (optimum pH 8.0). The major fatty acids were iso-C(15:0) (32.22%), anteiso-C(15:0) (31.64%) and iso-C(16:0) (17.38%). The peptidoglycan was of A4α type (L-Lys-Gly-L-Glu). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides, dimannosyl diacylglycerol, an unknown glycolipid and two unknown phospholipids. The quinone system comprised menaquinones MK-7 (91.9%) and MK-8 (8.3%). The DNA G+C content of strain YIM 100590(T) was 56.2 mol%. Chemotaxonomic data indicated that the strain belongs to the family Micrococcaceae. On the basis of morphological and chemotaxonomic data and phylogenetic analysis, strain YIM 100590(T) is considered to represent a novel species of a new genus within the family Micrococcaceae, for which the name Enteractinococcus coprophilus gen. nov., sp. nov. is proposed. The type strain of Enteractinococcus coprophilus is YIM 100590(T) (=DSM 24083(T)=JCM 17352(T)). Yaniella fodinae DSM 22966(T) was transferred to the new genus as Enteractinococcus fodinae comb. nov. (type strain G5(T)=DSM 22966(T)=JCM 17931(T)=MTCC 9846(T)).

[Distribution and characteristics of soil antagonistic actinomycetes on northern slope of Taibai Mountain, Qinling].

Twelve representative soil samples were collected from different altitudes on the northern slope of Taibai Mountain to study the distribution and characteristics of soil antagonistic actinomyces by using agar block method. There existed a great deal of soil antagonistic actinomyces in the study area. Among the 141 actinomycete strains isolated, 116 strains (82.3%) showed antagonism toward 12 target bacteria or fungi. The antagonistic strains at altitudes 800-1845, 3488, 3655, and 3670 m occupied 73.7% -86.8%, 81.3%, 78.9% and 82.3% of the total, respectively. 42.1% of the strains at altitudes 1200-2300 m and > 3400 m showed strong and broad spectrum antagonistic activity, suggesting that there was a great potential for the isolation of actinomycete strains with strong anti-biotic capability at these altitudes. 24.1% of the antagonistic actinomycetes showed antagonism against Staphyloccocus aureu, and 2.4%, 6.9% and 11.2% of them showed activity toward Verticillium dahliae in cotton, Phytophthora sp. in strawberry and Neonectria radiciccla in ginseng, respectively. This study showed that the soil actinomycete antagonistic potentiality (SAAP) could be used as a quantitative indicator to evaluate the potential of antagonistic actinomycete resources in soil.

Rubellimicrobium roseum sp. nov., a Gram-negative bacterium isolated from the forest soil sample.

A novel pink-coloured, non-spore-forming, non-motile, Gram-negative bacterium, designated YIM 48858(T), is described by using a polyphasic approach. The strain can grow at pH 6.5-9 (optimum at pH 7) and 25-30 degrees C (optimum at 28 degrees C). NaCl is not required for its growth. Positive for oxidase and catalase. Urease activity, nitrate reduction, starch and Tween 80 tests are negative reaction. 16S rRNA gene sequence similarity studies showed that strain YIM 48858(T) is a member of the genus Rubellimicrobium, with similarities of 96.3, 95.7 and 95.5% to Rubellimicrobium mesophilum MSL-20(T), Rubellimicrobium aerolatum 5715S-9(T) and Rubellimicrobium thermophilum DSM 16684(T), respectively. Q-10 was the predominant respiratory ubiquinone as in the other members of the genus Rubellimicrobium. The major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphoglycolipid, glycolipid and the major fatty acids were C18:1 omega7c, C16:0 and C10:0 3-OH, which are very different from the valid published species. The DNA G + C content was 67.7 mol%. Both phylogenetic and chemotaxonomic evidence supports that YIM 48858(T) is a novel species of the genus Rubellimicrobium, for which the name Rubellimicrobium roseum sp. nov. is proposed. The type strain is YIM 48858(T) (=CCTCC AA 208029(T) =KCTC 23202(T)).

[Ecological distribution and antimicrobial effects of soil actinomycetes in artificial vegetation systems in Shazhuyu of Qinghai, China].

In order to probe into the effects of artificial vegetation rehabilitation on soil actinomycetes, dilution plate and agar block methods were used to investigate the ecological distribution and antimicrobial effects of actinomycetes in sandy soil in Shazhuyu area of Qinghai after artificial vegetation restoration. The results showed that with the vegetation rehabilitation and the improvement of vegetation coverage on alpine sandy dry land, the quantity of soil actinomycetes increased significantly, being 145.4% higher in the grassland transferred from farmland than in sandy land. The quantity of soil Micromonospora in grassland transferred from farmland was about six times as much as that in sandy land. The average selection rate of antimicrobial actinomycetes was increased greatly, with the antimicrobial actinomycetes in the soil of grassland transferred from farmland, the antibacterial actinomycetes in the soil of natural grassland, and the pathogenic fungus resistant aetinomycetes in the soil of forestland being approximately 2, 3.2 and 1.5 times as much as those in the soil of sandy land, respectively. Vegetation coverage and soil nutrients had great influences on the quantities of actinomycetes and antimicrobial actinomycetes. The contents of soil organic matter and alkali-hydrolyzable nitrogen and the yield of fresh grasses had significant correlations with the quantities of actinomycetes (P < 0.01), and the content of soil organic matter and the yield of fresh grasses significantly correlated with the strain numbers of antimicrobial actinomycetes (P < 0.01). Furthermore, vegetation coverage and the contents of soil total nitrogen, total phosphorous, total potassium, total salt, and available potassium had significant correlations with the total quantities of actinomycetes, Streptomycetes, and Micromonospora (P < 0.05).

[Effects of microwave irradiation on isolation of soil actinomycetes].

Dilution plate- and agar block methods were employed to study the effects of microwave irradiation on the isolation of soil actinomycetes. The results showed that: 1) Microwave irradiation could significantly increase the total quantity of isolated actinomycetes. With the increasing duration of microwave irradiation, the total quantity of actinomycetes in soils with high organic matter content tended to increase first and decrease then. This quantity on GA and HA culture medium increased by 8.3%-92.6% and 24.4%-108.5% when the irradiation lasted 3-15 minutes, but decreased by 62.1%-78.8% and 41.4%-79.8%, respectively when the irradiation lasted 18-24 minutes, in comparison with that on the control medium. Microwave irradiation showed no remarkable effects on the total quantity of actinomycetes in the soils with low organic matter content. 2) Microwave irradiation also exerted remarkable effects on the number of actinomycetes species. With the increase of irradiation duration, the actinomycetes species number in soils with high organic matter content appeared to increase first and decrease then. When the irradiation lasted 3-24 minutes, the newly identified actinomycetes species on GA and HA culture medium, which included rare actinomycete genera such as Promicromonospora and Streptoverticillium, took up 62.5%-85.7% and 66.7%-83.3% of all the actinomycetes species respectively, and the genus Streptmycete also had obvious variation. Soils with low organic matter content showed the similar tendency. 3) Microwave irradiation could exert remarkable effects on the percentages of antimicrobial actinomycetes strains to all test actinomycete strains. When the microwave irradiation lasted 6, 9, and 15 minutes, the percentages of antimicrobial antinomycetes strains on the culture mediums increased by 66.7%, 66.7%, and 83.3%, and the newly identified antimicrobial antinomycetes strains made up 70.0%, 90.0%, and 81.8% of all the antimicrobial antinomycetes strains, respectively.

[Nutrient contents and microbial populations of aeolian sandy soil in Sanjiangyuan region of Qinghai Province].

Sanjiangyuan region (the headstream of three rivers) in Qinghai Province of China is the highest and largest inland alpine wetland in the world. The study on the nutrient contents and microbial populations of aeolian sandy soils in this region showed that soil organic matter content increased with the evolution of aeolian sand dunes from un-stabilized to stabilized state, being 5.9 and 3.8 times higher in stabilized sand dune than in mobile and semi-stabilized sand dunes, respectively. Soil nitrogen and phosphorus contents increased in line with the amount of organic matter, while potassium content and pH value varied slightly. The microbial populations changed markedly with the development of vegetation, fixing of mobile sand, and increase of soil nutrients. The quantities of soil bacteria, fungi and actinomycetes were 4.0 and 2.8 times, 19.6 and 6.3 times, and 12.4 and 2.6 times higher in stabilized and semi-stabilized sand dunes than in mobile sand dune, respectively, indicating that soil microbial bio-diversity was increased with the evolution of aeolian sand dunes from mobile to stabilized state. In addition, the quantities of soil microbes were closely correlated with the contents of soil organic matter, total nitrogen, and available nitrogen and phosphorus, but not correlated with soil total phosphorus, total and available potassium, or pH value.