Antibiotic Spectrum and Stability of Crude Extract of Extracellular Metabolites from Bacillus mageterium LB01-17

Crop pathogens including fungi and bacteria seriously affect the quality and yields of agricultural products. The purpose of this study was to detect the antibiotic spectrum of the crude extract of extracellular metabolites produced by Bacillus megaterium LB01-17 and its stability to heat, acid, alkali and ultraviolet light. The methods of mycelium growth rate and inhibitory zones were used to test the antimicrobial activity of the crude extract on 13 kinds of crop pathogenic fungi and 6 kinds of bacteria. The activity stability of the crude extract was determined under different pH values, acid-base environment and UV radiation time with Colletotrichum gloeosporioides in postharvest mango as the indicator strain. The crude extract displayed broad spectrum activity against all tested fungi with the inhibition rate on 5 kinds of fungi more than 83 %. Inhibitory effects of the crude extract on the growth of 6 kinds of bacteria were also observed and strongest inhibition to Xanthomonas oryzae pv.oryzae in rice was showed (inhibitory zone diameter 22.37 mm). By the detection of stability of the crude extract to acid, alkali, heat and UV, the results demonstrated that the inhibition rate of the crude extract against Colletotrichum gloeosporioides was stable at pH 2-8 and 77.13 % of inhibition rate was still kept after treated at 140 ºC for 20 min and the crude extract had a stable activity to UV, and the inhibition rate was almost unchanged after 6 h.

Whole Genome Sequencing and Tn5-Insertion Mutagenesis of Pseudomonas taiwanensis CMS to Probe Its Antagonistic Activity Against Rice Bacterial Blight Disease

The Gram-negative bacterium Pseudomonas taiwanensis is a novel bacterium that uses shrimp shell waste as its sole sources of carbon and nitrogen. It is a versatile bacterium with potential for use in biological control, with activities including toxicity toward insects, fungi, and the rice pathogen Xanthomonas oryzae pv.oryzae (Xoo). In this study, the complete 5.08-Mb genome sequence of P. taiwanensis CMS was determined by a combination of NGS/Sanger sequencing and optical mapping. Comparison of optical maps of seven Pseudomonas species showed that P. taiwanensis is most closely related to P. putida KT 2400. We screened a total of 11,646 individual Tn5-transponson tagged strains to identify genes that are involved in the production and regulation of the iron-chelator pyoverdine in P. taiwanensis, which is a key anti-Xoo factor. Our results indicated that the two-component system (TCS) EnvZ/OmpR plays a positive regulatory role in the production of pyoverdine, whereas the sigma factor RpoS functions as a repressor. The knowledge of the molecular basis of the regulation of pyoverdine by P. taiwanensis provided herein will be useful for its development for use in biological control, including as an anti-Xoo agent.

Transcriptome-Based Analysis of Phosphite-Induced Resistance against Pathogens in Rice

Phosphite (PHI) has been used in the management of Phytophthora diseases since the 1970s.We assessed the effect of PHI on controlling the incidence of Xanthomonas oryzae pv.oryzae and Pyricularia grisea. As a result, PHI application significantly inhibited the incidence of the diseases. To clarify the molecular mechanism underlying this, a transcriptome study was employed. In total, 2064 differentially expressed genes (DEGs) were identified between control and PHI treatment. The key DEGs could be classified into phenylpropanoid biosynthesis (ko00940), starch and sucrose metabolism (ko00500), and plant hormone signal transduction (ko04075). The expressions of defense-related genes had a higher expression lever upon PHI treatment. This study provides new insights into the mechanism of protection effect of PHI against pathogens.

RESEARCH ON PRODUCTION OF ENVIRONMENTALLY FRIENDLY ANTAGONISTIC MICROORGANISMS IN THE PREVENTION OF RICE BLIGHT DISEASE FOR AGRICULTURAL PRODUCTION IN VIETNAM

Bệnh bạc lá lúa là một trong những bệnh phổ biến ở các nước trồng lúa, trong đó có Việt Nam. Các phương pháp nghiên cứu được sử dụng là đánh giá sự sinh trưởng của vi sinh vật, xác định tính đối kháng của vi sinh vật, khả năng đồng sinh trưởng, hiệu quả của sản phẩm, đánh giá độc tính của chế phẩm,... Kết quả nghiên cứu cho thấy các chủng vi sinh vật thuộc nhóm xạ khuẩn Steptomyces sp., Bacillus spp có khả năng sinh chất đối kháng với vi khuẩn Xanthomonas oryzae pv.oryzae (Xoo) gây bệnh bạc lá lúa, với 4 chủng vi khuẩn PD17, PD13.1, KND, KXT1 và 2 chủng xạ khuẩn XKBL2, XKBL3; xác định được các điều kiện phù hợp cho sinh trưởng: nhiệt độ 200C -500C, pH 5,5-8, môi trường lên men để sản xuất chế phẩm (dạng bột lên men 7 ngày và dạng lỏng lên men 5 ngày). Quy trình sản xuất chế phẩm được triển khai trong phòng thí nghiệm và trong thực tiễn nhằm đánh giá được tính thích nghi, kiểm tra độc tính, tính toán hiệu quả kinh tế, khẳng định hiệu quả tại hợp tác xã Mộc Bắc, huyện Duy Tiên, tỉnh Hà Nam.

Proteomic study of salt tolerant cyanobacterium Anabaena sp. BHUAR002 isolated from Usar soil

Salt stress leads to an alteration in protein profile and induction of stress-specific proteins. The SDS – PAGE analysis of total soluble proteins of Anabaena sp. BHUAR002 (Accession no. bankit1353506 HM235817) exposed to 500 mM NaCl for 24 h revealed inhibition of host proteins, induction of selected proteins and appearance of some new proteins. In view of the appreciable alteration in total soluble protein profile after 500 mM salt treatment for 24 h, this dose was selected for further physiological, biochemical and proteomic analysis of the response of Anabaena sp. BHUAR002 to salinity and to examine the relationship between these responses. Further, 2DE of the total soluble protein of Anabaena sp. BHUAR002 showed 73 spots present only in control, 43 spots present only in stress and 15 differentially expressed spots present in both control and stress but show different levels of expression. This may be due to disturbance of cellular homeostasis by salt stress. Out of fifteen, Six spots were identified after MALDI-TOF MS analysis were identified as Manganese and iron Superoxide dismutase [Anabaenavariabilis ATCC 29413], Cytidine deaminase [Porphyromonas venonis 60-3], Phycobilisome Protein [Nodularia Spumigena CCY9414], DNA replication and repair protein recF [Yersinia aldovae ATCC35236], IS1112 transposase [Xanthomonas oryzae pv.oryzae PXO99A] and TP901 family phage tail tape measure protein [Xanthobacter autotrophicus Py2].

Formulasi Bakteri Filosfer Padi dan Aplikasinya untuk Mengendalikan Penyakit Hawar Daun Bakteri

Xanthomonas oryzae pv.oryzae is a casual agent of bacterial leaf blight disease (BLB) of rice. The disease can infect every phases of plant growth and can reduce rice production. In the previous study we have isolated nonpathogenic phyllosphere bacteria against X. oryzae pv.oryzae. For further study, in the present work we developed the formulation of the phyllosphere bacteria and tested their effectiveness against BLB in greenhouse trials. Out of three alternative medium used in culturing bacterial cell biomass, it was revealed that potato broth served as the best medium in comparison with skim milk molasses and bran extract. Formulation of phyllosphere bacteria was conducted by using of talc as main carrier, i.e. approximately 109 cfu g-1of main carrier. Application of the formula on rice leaves indicated that BFV 60, BFF 69, BFR 203 and BFR 153 were the best formula for controlling BLB and were able to reduce disease incidence up to 40.73%, 39.72%, 39.26%, and 28.07%, respectively

Marker Assisted Selection for Bacterial Leaf Blight Rice Mutant Lines Resistant

Induction of mutation using gamma rays for improving of Mira-1 rice variety has been conducted.Rice mutant lines M2 generation have been obtained from mutation by the doses of 25, 50, 75, 100, 150 and200 Gy of gamma rays. Selection of mutant lines tolerant to the disease was only observed in the field neithergenetically. Marker assisted selection is a tool to obtain a new rice variety tolerant to the disease of bacterialleaf blight (BLB) genetically. Xanthomonas oryzae pv.oryzae (Xa) was the pathogen of BLB, and the identificationof rice mutant lines which were containing of Xa5, Xa13 and Xa21 genes have been done using PolymeraseChain Reaction ( PCR ) method. The result showed that one mutant line, and four mutant lines from mutationby the doses of 25 Gy and 150 Gy were containing Xa5, Xa13 and Xa21 genes the same as that of Code ricevariety as positive control, and none in Kencana Bali rice variety as negative control. Mira-1 rice variety as theparent plant was only contains Xa5 and Xa21 genes. The doses of 50 Gy and 100 Gy were very affective onremoving of all bands for identification of those genes. The purpose of this research was to obtain the mutantlines which were contain of those Xa genes as indicator for resistant to BLB disease genetically.

KARAKTERISASI RIZOBAKTERI YANG BERPOTENSI MENGENDALIKAN BAKTERI Xanthomonas oryzae pv. oryzae DAN MENINGKATKAN PERTUMBUHAN TANAMAN PADI

Characterization of rhizobacteri having potential to control Xanthomonas oryzae pv. oryzae and increase plant growth of rice. Rhizobacteria which are isolated from root could produce HCN, siderophore, and plant growth regulator, induce systemic resistance, and are increase uptake of plant nutrition such as phosphate. The objective of this research was to characterize rhizobacteri as controling agent for Xanthomonas oryzae pv.oryzae (Xoo) and as plant growth promoter. The results show that the isolates of P. diminuta A6, P. aeruginosa A54, B.subtilis 11 /C, and B. subtilis 5/B inhibited the growth of Xoo. B. subtilis 5/B isolate produced the highest siderophore activity, followed by of P. aeruginosa A54, P. diminuta A6 and B. subtilis 11/C. Only P. diminuta A6 isolate produced HCN. The results also showed that all rhizobacteri produced IAA i.e. B.subtilis 5/B (22.10 µg/ml), B. subtilis 11/C (19.05 µg/ml), P. diminuta A6 (8.68 ug/ml), and P. aeruginosa A54 (2.95 µg/ml). The content of phosphatase enzyme was as folows B.subtilis 5/B (2.78 units/ ml), B.subtilis 11/C (5.7 units/ml), P. diminuta A6 (2.25 units/ml), and P. aeruginosa A54 (5.71 units / ml). Content of peroxidase enzymes in plants that were treated by using isolates was as follows B.subtilis 5/B (1.30 x 10-3 units/mg protein), P. aeruginosa A6 (1.20 x 10-3 units/mg protein), B.subtilis 11/C (1.15 x 10-3 units/mg protein), and P. aeruginosa A54 (1.05 x 10-3 units/mg protein).