Response of Bacterial Community and Enzyme Activity of Greenhouse Tomato under Different Irrigation Systems

The micro-sprinkler irrigation mulched(MSM)has been suggested as a novel water-saving approach in con-trolled environment agriculture.However,the effects of microbial community structure and enzyme activity in the rhizosphere soil on crop growth under MSM remain unclear.This study conducted a randomized experimen-tal design using greenhouse tomatoes to investigate changes in bacterial community structure and enzyme activity in rhizosphere soil under different irrigation frequencies(F)and amounts(I)of MSM.Thefindings revealed that with the increase of F or I,The total count of soil bacteria in tomatoesfirst rose and then fell in terms of Opera-tional Taxonomic Units(OTUs)classification.Compared to other F,the most abundance of nitrogen and phos-phorus metabolism genes and enzyme activities were observed with a 5-day F.Moreover,the diversity of soil bacterial community structure initially rose before eventually declining with the increase of the I.Applying 1.00 Epan(cumulative evaporation of a 20 cm standard pan)under MSM helped boost the abundance of nitrogen and phosphorus metabolism functional genes in soil bacteria,ensuring higher enzyme activities related to nitro-gen,carbon,and phosphorus metabolism in the rhizosphere soil of tomatoes.Tomatoes’yield initially rose before eventually declining with the increase in F or I,whereas I had a more significant effect on yield.A 1.00%increase in I yielded a minimum of 39.24%increase in tomato yield.The study showed a positive correlation between soil bacterial community,soil enzyme activity,and greenhouse tomato yield under MSM.Considering the results comprehensively,the combined irrigation mode of F of 5 d and I of 1.00 Epan was recommended for greenhouse tomatoes under MSM.This conclusion provides theoretical support for water-saving practices and yield improve-ment in facility agriculture,especially tomato cultivation.

Benthic bacterial communities indicate anthropogenic activity footprints in coastal area under long-term marine spatial planning practice

Marine spatial planning(MSP)is designed to divide the sea area into different types of functional zones,to implement corresponding development activities.However,the long-term impacts of anthropogenic activities associated with MSP practice on the marine microbial biosphere are still unclear.Yalu River Estuary,a coastal region in northeast of China,has been divided into fishery&agricultural(F&A)zone,shipping&port(S&P)zone and marine protected area(MPA)zone by a local MSP guideline that has been run for decades.To examine the effects of long-term executed MSP,benthic bacterial communities from different MSP zones were obtained and compared in this study.The results revealed significant differences in the bacterial community structure and predict functions among different zones.Bacterial genera enriched in different zones were identified,including SBR1031 in MPA,Woeseia and Sva0996 in S&P,and Halioglobus in F&A.In addition,correlations between some bacterial genera and sediment pollutants were uncovered.Furthermore,bacteria related to sulphide production were more abundant in the F&A zone,which was according to the accumulation of sulphides in this area.Moreover,bacteria associated with chemoheterotrophy and fermentation were more predominant in the S&P zone,consistent with high levels of organic matter and petroleum caused by shipping.Our findings indicated benthic bacterial communities could bring to light the anthropogenic activity footprints by different activities induced by long-term MSP practice.

Phytochemical and anti-bacterial activity of epidermal glands extract of Christella parasitica (L.) H. Lev.

Objective:To study the morphology,biochemistry and bioactivity of the epidermal glands of the glandular morphotype of Christella parasitica(C.parasitica)(L.) H.Lev.Methods: Morphological studies on epidermal glands were earned out by using light microscope and scanning electron microscope.To prepare the extract,the shade-dried fronds of glandular morphotype were soaked in acetone.For antibacterial studies paper disc method was followed by using various pathogenic bacteria.Results:Detailed micromorphological,phytochemical and bioactivity studies on a medicinal fern C.parasitica(L.) H.Lev.showed its inlraspecific variation in antibacterial activity.The presence or absence of the epidermal glands was the key factor for antibacterial activity in the morphovariants of this species.The epidermal glands were orange-coloured,stalked and elongated ones of about 84.2μm×45μm,and distributed on the undersurface of cosla,coslules and veins in croziers,young and mature leaves.Frequency of glands varied from 15/cm on costa in mature leaves to 140/cm on costules in croziers.The acetone extract of the glands showed antibacterial activities and also toxic effect against mosquito larvae and tadpoles of frog.Preliminary phytochemical analysis and HPLC studies of the gland extract showed the presence of various kinds of terpenoids,alkaloids,tannins,saponins and flavonoids in it.Conclusions:The present study shows that epidermal glands of the glandular morphotype of C. parasitica(L.) H.Lev.have several bioactive compounds and such rare moiphovariant should be conserved in nature.The next step is to isolate the pure compounds and to screen the bioactivity of individual compounds of the epidermal glands.

Antibacterial activity of Lawsonia inermis Linn(Henna) against Pseudomonas aeruginosa

Objective:To investigate the antibacterial activity of henna(Lawsonia inermis Linn) obtained from different regions of Oman against a wide array of micro-organisms.Methods:fresh henna samples were obtained from different regions of Oman as leaves and seeds,100 g fresh and dry leaves and SO g of fresh and dry seeds were separately soaked in 500 mL of ethanol for three days,respectively,with frequent agitation.The mixture was filtered,and the crude extract was collected.The crude extract was then heated,at 48 ℃ in a water bath to evaporate its liquid content.The dry crude henna extract was then tested for its antibacterial activity using well-diffusion antibiotic susceptibility technique.Henna extracts were investigated for their antibacterial activity at different concentrations against a wide array of different micro-organisms including a laboratory standard bacterial strain of Pseudomonas aeruginosa(NCTC 10662)(A aeruginosa) and eleven fresh clinical isolates of P.aeruginosa obtained from patients attending the Sultan Qaboos University Hospital(SQUH).2-Hydroxy-p-Nathoqinone-Tech(2-HPNT, MW=174.16,C_(10)H_40_3) was included as control(at 50%concentration) along with the henna samples tested.Results:Henna samples demonstrated antibacterial activity against all isolates but the highest susceptibility was against P.aeruginosa with henna samples obtained from Al-sharqyia region.Conclusions:Omani henna from Al-sharqyia region demonstrates high in vitro anti-P. aeruginosa activity compared with many henna samples from different regions of Oman.

Antibacterial activity of plant methanolic extracts on a field isolate of <i>Pseudomonas syringae</i>pvtomato from the Casablanca region (Morocco)

A bacterial field isolate recovered from infected tomato plants in a green-house at Sidi Rehal, a region near Casablanca city (Morocco), was identified as the gammaproteobacterium Pseudomonas syringae pv. tomato DC3000 strain, the causal agent of bacterial speck. The bacterial isolate was characterized by morphological, biochemical and molecular biological tests, its growth curves carried out in various culture media, and its phytopathogenicity verified by infection tests. A screening was performed to evaluate the antibacterial activity of methanolic extracts of 12 selected Moroccan plants against the P. syringae pv. tomato DC3000 isolate, and Agar-well diffusion and Broth microdilution methods were used to determine minimum inhibitory and minimum bactericidal concentrations. Among the methanolic extracts tested, only those of Nigella sativa, Geranuim robertianum, Aizoon canariense and Rubia peregrine showed clear inhibitory and bactericidal activities, although the highest values were achieved with N. sativa, a plant used in Morocco as a spice, condiment and medicinal treatment.

Anti-fungal and anti-bacterial activities of ethanol extracts of selected traditional Chinese medicinal herbs

Objective:To evaluate in ritro antimicrobial activities of selected 58 ethno-medicinal plant extracts with a view to assess their therapeutic potential.Methods:A total of 58 traditional Chinese medicinal plants were carefully selected based on the literature review and their traditional use.The antimicrobial activities of ethanol extracts of these medicinal plants were tested against fungi(Aspergillus funigaius),yeast(Candida albicans),gram-negative(Acirelobacter haumannii and Pseudornnruis aeruginosa)and gram-positive bacteria(Staphglococcus aureus).The activities were tested at three different concentrations of 1.00,0.10 and 0.01 mg/mL.The data was analysed using Gene data Screener program.Results:The measured antimicrobial activities indicated that out of the 58 plant extracts,15 extracts showed anti-fungal activity and 23 extracts exhibited anti-bacterial activity.Eight plant extracts have exhibited both anti-bacterial and anti-fungal activities.For instance,Eucommia ulmoides,Pohgonum cuspidcrtum,Poria cocas and Uncaria rhineophylla showed activity against both bacterial and fungal strains,indicating their broad spectrum of activity.Conclusions:The results revealed that the ethanol extracts of 30 plants out of the selected 58 possess significant antimicrobial activities.It is interesting to note that the findings from the current study are consistent with the traditional use.A clear correlation has also been found between the antimicrobial activity and the flavonoid content of the plant extracts which is in agreement with the literature.Hence.the results presented here can be used to guide the selection of potential plant species for the isolation and structure elucidation of novel antimicrobial compounds in order to establish the structure-activity relationship.This in turn is expected to lead the way to the discovery of novel antimicrobial agents for therapeutic use.

Detection of Ca^(2+)-dependent acid phosphatase activity identifies neuronal integrity in damaged rat central nervous system after application of bacterial melanin

The study aims to confirm the neuroregenerative effects of bacterial melanin （BM） on central nervous system injury using a special staining method based on the detection of Ca^2＋-dependent acid phosphatase activity. Twenty-four rats were randomly assigned to undergo either unilateral destruction of sensorimotor cortex （group I; n = 12） or unilateral rubrospinal tract transection at the cervical level （C3-4） （group II; n = 12）. In each group, six rats were randomly selected after surgery to undergo intramuscular injection of BM solution （BM subgroup） and the remaining six rats were intramuscularly in）ected with saline （saline subgroup）. Neurological testing confirmed that BM accelerated the recovery of motor function in rats from both BM and saline subgroups. Two months after surgery, Ca^2＋-dependent acid phosphatase activity detection in combination with Chilingarian＇s calcium adenoside triphosphate method revealed that BM stimulated the sprouting of fibers and dilated the capillaries in the brain and spinal cord. These results suggest that BM can promote the recovery of motor function of rats with central nervous system injury; and detection of Ca^2＋-dependent acid phosphatase activity is a fast and easy method used to study the regeneration-promoting effects of BM on the injured central nervous system.

Extraction of Flavonoids and Polyphenols from Coronatinetreated Mulberry Leaves and Evaluation of Their Antibacterial Activity against Pseudomonas syringae

Flavonoids and polyphenols are the main secondary metabelites in mulberry leaves, which have multiple biological functions such as antibacterial activity, free radical scavenging activity and antioxidant activity. In this paper, the parameters for the extraction of flavonoids and palyphenols from eoronatine （ COR）- treated mulberry leaves were optimized, and the components of the extracts were analyzed by high performance liquid chromatography （ HPLC）, and their antibacterial activity against Pseudomonas syringae, which causes mulberry bacterial blight, was evaluated in vitro to explore the mechanism how COR acted as a plant immune elicitor to improve the resistance of mulberry to bacterial blight. The results showed that ethanol concentration of 70%, extraction temperature of 80 ℃, extraction duration of 6 h and solid-liquid ratio of 1 ： 40 were the optimal parameters for the extraction of flavonoids and polyphenols from mulberry leaves. Flavonoids and polyphenols were mostly distributed in ethyl acetate and n-butyl alcohol fractions which showed better antibacterial activity than petroleum ether, dichloromethane and water fractions. Meanwhile, the antibacterial activity of ethyl acetate and n-butyl alcohol fractions of COR-treated mulberry leaves were more evident than that of water-treated mulberry leaves. Scanning electron microscopy showed that flavonoids and pelyphenols inhibited the growth of pathogenic bacteria by changing cell morphology, damaging cell wall structure and unbalancing cell osmotic pressure. HPLC analysis confirmed the contents of morin, quercetin, quereitrin, kaempferol, chlorogenic acid and rutin were increased to a different extent in COR-treated mulberry leaves. So it can be concluded that the increased contents of flavonoids and polyphenols induced by COR may be one of the reasons for the enhanced resistance to mulberry bacterial blight.

Adjuvant activity of Pasteurella multocida A strain,Pasteurella multocida B strain and Salmonella typhimurium bacterial DNA on cellular and humoral immunity responses against Pasteurella multocida specific strain infections in Balb/c mice

Objective: To evaluate the effects of Pasteurella multocida(P. multocida) vaccines on the expression and release of antibodies, interleukin(IL)-6 and IL-12 by serum. Methods: Balb/c mice were immunized with two formalin and iron inactivated vaccine doses within 2 weeks. The vaccines were adjuvant with P. multocida A strain, P. multocida B strain and Salmonella typhimurium bacterial DNA(AbDNA, BbDNA and SbDNA for short, respectively). The animals were challenged 4 weeks after immunization. Blood of mice was collected to detect the change of specific antibody, IL-6, and IL-12 using ELISA. Results: The specific antibody and interleukins in the immunized group increased significantly compared to the control mice after vaccination and challenge(P<0.05). The highest release of these cytokines was obtained by P.multocida inactivated with iron and adjuvant with AbDNA at a concentration of 25 μg/mL. The antibody titer peak was 0.447 in mice vaccinated with iron-killed whole-cell antigen adjunct with AbDNA. The time-courses of release showed that bacterial DNA was able to stimulate IL-6 and IL-12 production more than alum(P<0.05). Conclusions: Our findings introduce that bacterial DNA is capable of releasing an immunological response with several cytokines.These indicate that bacterial DNA entrapped with killed P. multocida antigen is a new and effective adjuvant to enhance specific immunity and resistance of animal against the infectious pathogen, which could simplify the development of highly promising strong adjuvant.

Comparative Study of Antibacterial Activity of Bacterial Cellulose/AgNPs Composites Prepared by Different Methods

Bacterial cellulose(BC) is a type of nanoscale cellulose produced by microorganisms.In this work,BC films were utilized as a template to in situ synthesize silver nanoparticles(AgNPs) by a variety of simple chemical strategies,including chemical reduction with NaBH4 or vitamin C,hydrothermal treatment and UV radiation.A comparative study of the formation of AgNPs such as the silver particle size and silver content,as well as the antibacterial activity of the BC-AgNPs nanocomposites by different preparation methods and reaction conditions was investigated.A beneficial support was provided for future applications of AgNPs contained BC composites with antibacterial properties.

Synthesis and Antibacterial Activity of Urea and Thiourea Derivatives of Anacardic Acid Mixture Isolated from A Natural Product Cashew Nut Shell Liquid (CNSL)

Synthesis and antibacterial activity of some novel urea and thiourea derivatives (8a - 8k, 9a - 9f) of anacardic acid prepared from commercially available anacardic acid which is obtained from natural product Cashew Nut Shell Liquid (CNSL). Compounds (8a - 8k, 9a - 9f) were tested for Gram positive and Gram negative bacterial cultures. Most of the compounds were showed active compared with standard drug ampicilline.

<i>In-Vitro</i>Inhibitory Effect of Methanol Extracts of Chinese Herbal Drugs on Supercoiling Activity of Bacterial DNA Gyrase

A large number of Chinese herbal drugs (CHDs) exhibit antibacterial activities both in vivo and in vitro, but until now little is known regarding their inhibitory mechanisms. Bacterial DNA gyrase is a proven target for antibacterial agents. Aim of this study was to investigate the in-vitro inhibitory effect of methanol extracts of CHDs against supercoiling activity of bacterial DNA gyrase. Fifteen CHDs were selected and extracted with methanol, respectively. Inhibitory effect of the extracts on DNA gyrase was tested using gel-based DNA supercoiling assay. Among fifteen CHDs tested, methanol extracts of Lonicerae Japonicae Flos (S2), Taraxaci Herba (S7), Glycyrrhizae Radix et Rhizoma Praeparata cum Melle (S8) demonstrated an obvious inhibitory effect against supercoiling activity of DNA gyrase, and the others were either less active or could not be determined with the present method. Moreover, it was likely that S7 and S8 inhibit gyrase in a concentration-dependent manner. In conclusion, DNA supercoiling assay is a promising method to study the inhibitory activity of CHDs on bacterial DNA gyrase. Some CHDs do have gyrase-inhibitory activity as proposed. Further investigations are needed to elucidate the inhibition mechanism of these CHDs on supercoiling activity of gyrase.

Synthesis and Antibacterial Activity of Urea and hiourea Derivatives at C-8 Alkyl Chain of Anacardic Acid Mixture Isolated from a Natural Product Cashew Nut Shell Liquid (CNSL)

Synthesis and antibacterial activity of some novel urea and thiourea derivatives (7a-7k, 8a-8f) of anacardic acid prepared from commercially available anacardic acid which is obtained from natural product Cashew Nut Shell Liquid (CNSL). Compounds (7a-7k, 8a-8f) were tested for Gram positive and Gram negative bac- terial cultures. Most of the compounds were showed active compared with standard drug ampicilline.

The use of bacterial cellulose from kombucha to produce curcumin loaded Pickering emulsion with improved stability and antioxidant properties

Curcumin is a bioactive molecule with limited industrial application because of its instability and poor solubility in water.Herein,curcumin-loaded Pickering emulsion was produced using purified bacterial cellulose from fermented kombucha(KBC).The morphology,particle size,stability,rheological properties,and antioxidant activities of the curcumin-loaded Pickering emulsion were investigated.The fluorescence microscope and scanning electron microscopy images showed that the curcumin-loaded Pickering emulsion formed circular droplets with good encapsulation.The curcumin-load Pickering emulsion exhibited better stability under a wide range of temperatures,low p H,sunlight,and UV-365 nm than the free curcumin,indicating that the KBC after high-pressure homogenization improved the stability of the CPE.The encapsulated curcumin retained its antioxidant capacity and exhibited higher functional potential than the free curcumin.The study demonstrated that the KBC could be an excellent material for preparing a Pickering emulsion to improve curcumin stability and antioxidant activity.

Bacterial Community and Function of Biological Activated Carbon Filter in Drinking Water Treatment

Objective It aims to investigate the changes in composition and structure of bacterial communities de-veloping on biological activated carbon （BAC） particles, and the bacterial functions. Method A pilot plant had been in service for 180 days, aiming to develop bacterial communities on acti-vated carbon naturally. After 180 days of operation, the bacterial communities were determined by dena-turing gradient gel electrophoresis （DGGE） analyses of PCR-amplified 16S rRNA genes. The study on community composition and the phylogenetic relationships of the organisms was complemented by a se-quence analysis of cloned PCR products from 16S rRNA genes. Gas chromatorgaphy-mass （GC-MS） mea-surement was used to determine organic chemical composition of inflow and outflow water on the 300th day. TOC and NH 4 ＋ -N were also tested in this experiment. Results It showed that the stable bacterial structure did not develop on BAC particles until the 9th month during running time of the BAC filter. The communities were finally dominated by Pseudomonas sp., Ba-cillus sp., Nitrospira sp., and an uncultured bacterium. Stable bacterial communities played an important role in removal of NH 4 ＋ -N and total organic carbon （TOC）. Results from gas chromatorgaphy-mass （GC-MS） showed that 36 kinds of chemicals in feed water were eliminated, and concentrations of 5 kinds of chemicals decreased. These chemicals served as nutrients for the dominant bacteria. Conclusion The findings from the study suggested that the stability of microbial structure was beneficial for improving NH 4 ＋ -N and TOC removal efficiencies. The dominant bacteria had the advantage of biode-grading a wide range of organic chemicals and NH 4 ＋ -N.

CoN_(x)C active sites-rich three-dimensional porous carbon nanofibers network derived from bacterial cellulose and bimetal-ZIFs as efficient multifunctional electrocatalyst for rechargeable Zn–air batteries

In this work, a CoNxC active sites-rich three-dimensional porous carbon nanofibers network derived from bacterial cellulose and bimetal-ZIFs is prepared via a nucleation growth strategy and a pyrolysis process.The material displays excellent electrocatalytic activity for the oxygen reduction reaction, reaching a high limiting diffusion current density of -7.8 mA cm^(-2), outperforming metal–organic frameworks derived multifunctional electrocatalysts, and oxygen evolution reaction and hydrogen evolution reaction with low overpotentials of 380 and 107 mV, respectively. When the electrochemical properties are further evaluated, the electrocatalyst as an air cathode for Zn-air batteries exhibits a high cycling stability for63 h as well as a maximum power density of 308 mW cm^(-2), which is better than those for most Zn-air batteries reported to date. In addition, a power density of 152 mW cm^(-2) is provided by the solid-state Zn-air batteries, and the cycling stability is outstanding for 24 h. The remarkable electrocatalytic properties are attributed to the synergistic effect of the 3 D porous carbon nanofibers network and abundant inserted CoNxC active sites, which enable the fast transmission of ions and mass and simultaneously provide a large contact area for the electrode/electrolyte.

Extended activated sludge model no. 1 (ASM1) for simulating biodegradation process using bacterial technology

Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study extended this model in order to determine the fate of phosphorus during the biodegradation processes. When some of the kinetics parameters are modified using observed data from the restoration project of the Xuxi River in Wuxi City, China, from August 25 to 31 in 2009, the extended model shows excellent results. In order to obtain optimum values of coefficients of nitrogen and phosphorus, the mass fraction method was used to ensure that the final results were reasonable and practically relevant. The temporal distribution of the data calculated with the extended ASM1 approximates that of the observed data.

Caries-related factors and bacterial composition of supragingival plaques in caries free and caries active Algerian adults

Objective: To compare oral hygiene practices, education and social background, food intake and oral malodor of Algerian adults suffering from dental caries with normal controls, and to determine and compare the bacterial composition of the supragingival plaques from the above-mentioned groups.Methods: Participants completed a questionnaire and were clinically examined for dental caries using decayed, missing and filled teeth index according to the criteria laid down by the World Health Organization. Supragingival plaque samples were collected from 50 caries-free adults(CF) and 50 caries-active adults(CA). Standard procedures of culture and identification of aerobic and anaerobic bacteria were used. Data were analyzed using Chi-square test.Results: A total of 117 bacterial strains were isolated from supragingival plaques in CF group subjects, 76(64.96%) of them belonged to 9 aerobic genera, and 41(35.04%) to 9anaerobic genera(P < 0.05). While in the second group, 199 strains were isolated, 119(59.80%) of the strains belonged to 10 aerobic genera and 80(40.20%) to 10 anaerobic bacteria(P < 0.05). Streptococcus mutans, Enterococcus faecium, Aerococcus viridans,Actinomyces meyeri, Lactobacillus acidophilus and Eubacterium limosum showed a significantly higher prevalence in the CA group(P < 0.05). The findings revealed that CA group had a high sugar intake(80%). A significantly higher frequency of tooth brushing(P < 0.000) and a significantly less self-reported oral malodor(P < 0.000) and tooth pain(P < 0.000) were found in CF group, while there was no association of socioeconomic levels and intake of meal snacks with dental caries.Conclusions: This study confirms the association of some aciduric bacteria with caries formation, and a direct association of sugar intake and cultural level with dental caries.Furthermore, oral hygiene practices minimize the prevalence of tooth decay.

Dynamic changes in microbial activity and community structure during biodegradation of petroleum compounds:A laboratory experiment

With 110-d incubation experiment in laboratory, the responses of microbial quantity, soil enzymatic activity, and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whether certain biological and biochemical characteristics could serve as reliable indicators of petroleum hydrocarbon contamination in meadow-brown soil, and use these indicators to evaluate the actual ecological impacts of 50-year petroleum-refining wastewater irrigation on soil function in Shenfu irrigation area. Results showed that amendments of ~ 1000 mg/kg diesel fuel stimulated the growth of aerobic heterotrophic bacteria, and increased the activity of soil dehydrogenase, hydrogenperoxidase, polyphenol oxidase and substrate-induced respiration. Soil bacterial diversity decreased slightly during the first 15 d of incubation and recovered to the control level on day 30. The significant decrease of the colony forming units of soil actinomyces and filamentous fungi can be taken as the sensitive biological indicators of petroleum contamination when soil was amended with 〉15000 mg/kg diesel fuel. The sharp decrease in urease activity was recommended as the most sensitive biochemical indicator of heavy diesel fuel contamination. The shifts in community structure to a community documented by Sphingomonadaceae within a-subgroup of Proteobacteria could be served as a sensitive and precise indicator of diesel fuel contamination. Based on the results described in this paper, the soil function in Shenfu irrigation area was disturbed to some extent.

Rhizosphere Bacteria for Biocontrol of Bacterial Blight and Growth Promotion of Rice

Several bacterial strains were isolated from different rhizospheres. Among these, strain PDY7 exhibited strong antibacterial activity against the rice bacterial blight （BB） pathogen Xanthomonas oryzae pv. oryzae （Xoo） by the laboratory dual plate assays. The antibacterial property of the strain PDY7 was further investigated for the production of 2,4-diacetylphloroglucinol （DAPG）, which amplified a characteristic of 629-bp DNA fragment by PCR-based screening method using phlD primers. The application of phlD positive strains was carefully evaluated for disease control and growth promotion of rice plants under field conditions. The selected strain PDY7 suppressed the rice BB by 58.83% and 51.88% under glass house and field conditions, respectively. In addition, the strain PDY7 showed significant two-fold increase in root length （18.08 cm）, shoot length （29.81 cm）, and grain yield （96.07 g）. Strain PDY7 promoted the growth of rice plants by production of indole-3-acetic acid （IAA）, which was determined by high performance liquid chromatography （HPLC） analysis. Our findings suggest that PDY7 belongs to the P. fluorescens group and can serve as potential biocontrol of BB as well as biofertilizer agent for growth promotion of rice.