Rhizosphere-associated Alcaligenes and Bacillus strains that induce resistance against blast and sheath blight diseases, enhance plant growth and improve mineral content in rice.

AIMS: To examine the biocontrol activities of five rhizobacterial strains (i.e. Alcaligenes faecalis strains Bk1 and P1, Bacillus amyloliquefaciens strain Bk7 and Brevibacillus laterosporus stains B4 and S5), to control the rice blast and sheath blight diseases in greenhouse and to study their possible modes of action. METHODS AND RESULTS: Five potential plant growth-promoting rhizobacterial (PGPR) strains isolated from rice rhizospheres were tested for in vitro antifungal activities against Magnaporthe oryzae, Rhizoctonia solani, Botrytis cinerea and Fusarium graminearum. In vitro trials showed that three strains, Bk1, P1 and Bk7, were able to unanimously suppress the mycelial growth of the target pathogens. In greenhouse, the application of these three PGPR strains significantly suppressed the incidences of rice blast and sheath blight diseases. At 2 weeks after pathogen inoculation, the highest percentages of disease suppression were noted for Alc. faecalis strain Bk1 (72%) for rice blast, Alc. faecalis strain P1 (71%) for sheath blight, followed by B. amyloliquefaciens strain Bk7. Moreover, these strains significantly improved the plant growth, enriched the content of mineral nutrients in seedlings and increased the expression of major defence-related rice genes. All three strains were marked positive for phosphate solubilization, the production of indoleacetic acid, ammonia and siderophores and catalase activity. In addition, these strains were able to form biofilms and carried multiple lipopeptide biosynthetic genes as revealed by multiplex PCR. CONCLUSION: This study reports new potential biocontrol agents for blast and sheath blight diseases of rice. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to better understanding of the mechanisms involved in interaction between beneficial rhizobacteria, fungal pathogens and host plants.

A randomized controlled trial evaluating the efficacy of a 67% sodium bicarbonate toothpaste on gingivitis.

INTRODUCTION: In previous studies, toothpastes with high levels of sodium bicarbonate (>50%) have reduced gingival inflammation and oral malodour. This study compared the effects of brushing for 6 weeks with 67% (test group) or 0% (control group) sodium bicarbonate toothpaste on gingival health. METHODS: This was a single-centre, single examiner-blind, randomized, controlled, two-treatment, parallel-group study. Eligible subjects (≥18 years) had ≥20 gradable teeth, mild-to-moderate gingivitis, a positive response to bleeding on brushing and ≥20 bleeding sites. The primary objective was to compare the number of bleeding sites following twice-daily use of 67% sodium bicarbonate toothpaste or 0% sodium bicarbonate toothpaste after 6 weeks. Secondary endpoints included Modified Gingival Index (MGI), Bleeding Index (BI) and volatile sulphur compounds (VSC), assessed after 6 weeks. Safety was assessed by treatment-emergent oral soft tissue abnormalities and adverse events. RESULTS: Of 148 patients randomized (74 to each treatment), 66 (89.2%) completed the study in the test group, compared with 69 (93.2%) in the control group. Compared with the control group, the test group had a significant reduction in the number of bleeding sites at Week 6 (absolute difference - 11.0 [-14.0, -8.0], P < 0.0001; relative difference - 25.4%), together with significant reductions in MGI and BI (both P < 0.0001). Although the median reductions from baseline for VSC were numerically greater in the test group, the difference did not reach statistical significance (P = 0.9701). CONCLUSIONS: This 67% sodium bicarbonate toothpaste provided statistically significant improvements in gingival health and bleeding after 6 weeks of use.

Multiplex PCR assay for simultaneous detection of six major bacterial pathogens of rice.

AIMS: The aim of this study was to develop a multiplex PCR (mPCR) assay for rapid, sensitive and simultaneous detection of six important rice pathogens: Xanthomonas oryzae pv. oryzae, X. oryzae pv. oryzicola, Pseudomonas fuscovaginae, Burkholderia glumae, Burkholderia gladioli and Acidovorax avenae subsp. avenae. METHODS AND RESULTS: Specific primers were designed through a bioinformatics pipeline. Sensitivity of detection was established using both traditional PCR and quantitative real-time PCR on isolated DNA and on bacterial cells both in vitro and in simulated diseased seeds and the parameters were optimized for an mPCR assay. A total of 150 bacterial strains were tested for specificity. The mPCR assay accurately predicted the presence of pathogens among 44 symptomatic and asymptomatic rice seed, sheath and leaf samples. CONCLUSIONS: This study confirmed that this mPCR assay is a rapid, reliable and simple tool for the simultaneous detection of six important rice bacterial pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report of a method allowing simultaneous detection of six major rice pathogens. The ability to use crude extracts from plants without bacterial isolation or DNA extraction enhances the value of this mPCR technology for rapid detection and aetiological/epidemiological studies.

A consortium of rhizobacterial strains and biochemical growth elicitors improve cold and drought stress tolerance in rice (Oryza sativa L.).

In the present study, a consortium of two rhizobacteria Bacillus amyloliquefaciens Bk7 and Brevibacillus laterosporus B4, termed 'BB', biochemical elicitors salicylic acid and ß-aminobutyric acid (SB) and their mixture (BBSB) were investigated for cold and drought stress tolerance in rice plants. After withholding water for 16 days, rice plants treated with BBSB showed 100% survival, improved seedling height (35.4 cm), shoot number (6.12), and showed minimum symptoms of chlorosis (19%), wilting (4%), necrosis (6%) and rolling of leaves. Similarly, BB inoculation enhanced plant growth and reduced overall symptoms in rice seedlings subjected to 0 ± 5 °C for 24 h. Our results imply several mechanisms underlying BB- and BBSB-elicited stress tolerance. In contrast to the control, both treatments significantly decreased leaf monodehydroascorbate (MDA) content and electrolyte leakage, and increased leaf proline and cholorophyll content. Moreover, activities of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) increased 3.0- and 3.6-fold, respectively. Moreover, expression of OsMYB3R-2, OsDIL, OsDREB1A and OsCDPK13 genes was significantly up-regulated, suggesting that these genes play important roles in abiotic stress tolerance of rice. In addition, bacterial strains Bk7 and B4 were able to produce high amounts of IAA and siderophores, and colonise the plant roots, while only strain Bk7 exhibited the capability to form biofilms and solubilise inorganic phosphate. This study indicates that the BB and BBSB bio-formulations can be used to confer induced systematic tolerance and improve the health of rice plants subject to chilling and drought stress.

Comparison of the clinical efficacy of a new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm fluoride to a commercially available sensitive toothpaste containing 2% potassium ion on dentin hypersensitivity: a randomized clinical trial.

OBJECTIVE: This clinical study was designed to compare dentin hypersensitivity relief among subjects who brushed their teeth with a new toothpaste containing 8.0% arginine, calcium carbonate, and 1000 ppm fluoride as sodium monofluorophosphate (MFP) to subjects who brushed with a commercially available dentifrice containing 2% potassium ion as potassium nitrate over an eight-week period. METHODS: Adult male and female subjects from the New Delhi, India area were required to present two teeth that exhibited dentin hypersensitivity, both to tactile stimulation using the Yeaple Probe and to air blast stimulation delivered by a standard dental unit syringe. After an examination of the oral soft and hard tissues, qualifying subjects were randomly assigned one of the study dentifrices and a soft-bristled toothbrush, and were instructed to brush their teeth for one minute, twice daily (morning and evening), using only the toothbrush and dentifrice provided. No other oral hygiene practices were permitted over the course of the study. After two, four, and eight weeks of product use, subjects returned to the dental clinic for follow-up examinations of tactile and air blast sensitivity of the baseline-designated hypersensitive teeth. Examinations of the oral soft and hard tissues were also performed at these follow-up visits. RESULTS: Subjects who brushed with the new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm MFP exhibited statistically significant reductions (p < 0.05) in dentin hypersensitivity in response to tactile (36.2%, 33.1%, and 29.7%) and air blast (16.4%, 31.1%, 58.8%) stimuli when compared to the subjects who brushed with the 2% potassium ion as potassium nitrate dentifrice after two, four, and eight weeks, respectively. CONCLUSION: The use ofa new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm MFP provides greater efficacy in reducing dentin hypersensitivity when compared to a dentifrice containing 2% potassium ion, as potassium nitrate, after two, four, and eight weeks of product use.

Comparison of the clinical efficacy in reducing dentin hypersensitivity of a new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm sodium monofluorophosphate to a commercially available toothpaste containing 1000 ppm sodium monofluorophosphate: an eight-week clinical trial on adults in New Delhi, India.

OBJECTIVE: This clinical study evaluated relief from dentin hypersensitivity among subjects who brushed their teeth with a new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm fluoride as sodium monofluorophosphate (MFP) to subjects who brushed with a commercially available dentifrice containing 1000 ppm MFP over an eight-week period. METHODS: Adult subjects from the New Delhi, India area, with two teeth that exhibited dentin hypersensitivity, both to tactile stimulation using the Yeaple Probe and to stimulation using an air blast delivered by a standard dental unit syringe, were screened for study enrollment. Qualifying subjects were randomly assigned one of the study dentifrices and instructed to brush their teeth for one minute, twice daily (morning and evening) with the provided dentifrice. Follow-up examinations for dentin hypersensitivity were conducted after two, four, and eight weeks of product use. RESULTS: Subjects provided with the new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm MFP exhibited statistically significantly (p < 0.05) greater reductions in dentin hypersensitivity in response to tactile (81.9%, 90.5%, and 116.7%) and air blast (39.5%, 56.7%, and 76.7%) stimuli than subjects assigned the 1000 ppm MFP dentifrice after two, four, and eight weeks, respectively. CONCLUSION: The use of a new dentifrice containing 8.0% arginine, calcium carbonate, and 1000 ppm MFP provides superior efficacy in reducing dentin hypersensitivity (p < 0.05) than a control dentifrice containing 1000 ppm MFP alone after two, four, and eight weeks of use.

Experimental haematogenous pyelonephritis in mice with uropathogenic, enteropathogenic and enterotoxigenic Escherichia coli.

Acute haematogenous pyelonephritis was produced with known uropathogenic (075), enteropathogenic (0111) and enterotoxigenic (H10407) Escherichia coli in mice. The enterotoxigenic E. coli showed the highest bacterial counts in kidney and urine and was found to have the same potential for causing pyelonephritis as a known pyelonephritogenic strain both in untreated and corticosteroid treated mice. Enteropathogenic E. coli was found to be less pyelonephritogenic in untreated mice, but under the effect of corticosteroids it showed similar pyelonephritogenic potential.