Application of Bacterial Endophytes to Control Bacterial Leaf Blight Disease and Promote Rice Growth

Ying Shing Ooi,Nik M. I. Mohamed Nor,Go Furusawa,Munirah Tharek,Amir H. Ghazali 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.5

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

SOME FACTORS INFLUENCING TRI-L-ALANINE DISAPPEARANCE AND RUMEN BACTERIAL GROWTH YIELD IN VITRO

Ha, J.K.,Kennelly, J.J.,Lee, S.C. Asian Australasian Association of Animal Productio 1991 Animal Bioscience Vol.4 No.4

A series of in vitro incubation studies with washed rumen bacteria were conducted to determine the influence of incubation time and concentrations of peptides, alanine, ammonia nitrogen and carbohydrate on the rate of peptide disappearance and on bacterial growth. Disappearance rate of tri-alanine (ala3) under various conditions was between 30.6 and $58.2mg\;hr^-$ per gram bacterial dry matter. Ala3 was removed from the incubation medium in an almost linear fashion as incubation time and ala3 concentration was increased. Washed rumen bacteria utilized ala3 faster than di-l-alanine (ala2) at all concentrations. Adding 9mM carbohydrate significantly increased ala3 disappearance, but level of ammonia nitrogen had no influence on ala3 disappearance. The presence of alanine in the medium significantly lowered ala3 utilization by rumen bacteria. Bacterial dry matter and nitrogen growth yield were not influenced by alanine and peptides when incubation medium already contained a sufficient level of ammonia nitrogen. Increased ammonia nitrogen in the presence of ala3 did not stimulate bacterial growth. Carbohydrate significantly increased bacterial dry matter and nitrogen growth as expected. Results indicate that the rate of peptide utilization by rumen bacteria may be altered by type and concentration of peptides, and energy supply, and this may be mediated through changes in numbers and type of bacteria.

Bacillus oryzicola sp. nov., an Endophytic Bacterium Isolated from the Roots of Rice with Antimicrobial, Plant Growth Promoting, and Systemic Resistance Inducing Activities in Rice

Chung, Eu Jin,Hossain, Mohammad Tofajjal,Khan, Ajmal,Kim, Kyung Hyun,Jeon, Che Ok,Chung, Young Ryun The Korean Society of Plant Pathology 2015 Plant Pathology Journal Vol.31 No.2

Biological control of major rice diseases has been attempted in several rice-growing countries in Asia during the last few decades and its application using antagonistic bacteria has proved to be somewhat successful for controlling various fungal diseases in field trials. Two novel endophytic Bacillus species, designated strains YC7007 and $YC7010^T$, with antimicrobial, plant growth-promoting, and systemic resistance-inducing activities were isolated from the roots of rice in paddy fields at Jinju, Korea, and their multifunctional activities were analyzed. Strain YC7007 inhibited mycelial growth of major rice fungal pathogens strongly in vitro. Bacterial blight and panicle blight caused by Xanthomonas oryzae pv. oryzae (KACC 10208) and Burkholderia glumae (KACC 44022), respectively, were also suppressed effectively by drenching a bacterial suspension ($10^7cfu/ml$) of strain YC7007 on the rhizosphere of rice. Additionally, strain YC7007 promoted the growth of rice seedlings with higher germination rates and more tillers than the untreated control. The taxonomic position of the strains was also investigated. Phylogenetic analyses based on 16S rRNA gene sequences indicated that both strains belong to the genus Bacillus, with high similarity to the closely related strains, Bacillus siamensis KACC $15859^T$ (99.67%), Bacillus methylotrophicus KACC $13105^T$ (99.65%), Bacillus amyloliquefaciens subsp. plantarum KACC $17177^T$ (99.60%), and Bacillus tequilensis KACC $15944^T$ (99.45%). The DNA-DNA relatedness value between strain $YC7010^T$ and the most closely related strain, B. siamensis KACC $15859^T$ was $50.4{\pm}3.5%$, but it was $91.5{\pm}11.0%$ between two strains YC7007 and $YC7010^T$, indicating the same species. The major fatty acids of two strains were anteiso-$C_{15:0}$ and iso $C_{15:0}$. Both strains contained MK-7 as a major respiratory quinone system. The G+C contents of the genomic DNA of two strains were 50.5 mol% and 51.2 mol%, respectively. Based on these polyphasic studies, the two strains YC7007 and $YC7010^T$ represent novel species of the genus Bacillus, for which the name Bacillus oryzicola sp. nov. is proposed. The type strain is $YC7010^T$ (= KACC $18228^T$). Taken together, our findings suggest that novel endophytic Bacillus strains can be used for the biological control of rice diseases.

Bacterial Hash Function Using DNA-Based XOR Logic Reveals Unexpected Behavior of the LuxR Promoter

Pearson, Brianna,Lau, Kin H.,Allen, Alicia,Barron, James,Cool, Robert,Davis, Kelly,DeLoache, Will,Feeney, Erin,Gordon, Andrew,Igo, John,Lewis, Aaron,Muscalino, Kristi,Parra, Madeline,Penumetcha, Palla Korean Society for Bioinformatics 2011 Interdisciplinary Bio Central (IBC) Vol.3 No.3

Introduction: Hash functions are computer algorithms that protect information and secure transactions. In response to the NIST's "International Call for Hash Function", we developed a biological hash function using the computing capabilities of bacteria. We designed a DNA-based XOR logic gate that allows bacterial colonies arranged in a series on an agar plate to perform hash function calculations. Results and Discussion: In order to provide each colony with adequate time to process inputs and perform XOR logic, we designed and successfully demonstrated a system for time-delayed bacterial growth. Our system is based on the diffusion of ${\ss}$-lactamase, resulting in destruction of ampicillin. Our DNA-based XOR logic gate design is based on the op-position of two promoters. Our results showed that $P_{lux}$ and $P_{OmpC}$ functioned as expected individually, but $P_{lux}$ did not behave as expected in the XOR construct. Our data showed that, contrary to literature reports, the $P_{lux}$ promoter is bidirectional. In the absence of the 3OC6 inducer, the LuxR activator can bind to the $P_{lux}$ promoter and induce backwards transcription. Conclusion and Prospects: Our system of time delayed bacterial growth allows for the successive processing of a bacterial hash function, and is expected to have utility in other synthetic biology applications. While testing our DNA-based XOR logic gate, we uncovered a novel function of $P_{lux}$. In the absence of autoinducer 3OC6, LuxR binds to $P_{lux}$ and activates backwards transcription. This result advances basic research and has important implications for the widespread use of the $P_{lux}$ promoter.

Physiological and biochemical perspectives of non-salt tolerant plants during bacterial interaction against soil salinity

Radhakrishnan, R.,Baek, K.H. Elsevier Science B.V., Amsterdam. 2017 Plant Physiology and Biochemistry Vol. No.

<P>Climatic changes on earth affect the soil quality of agricultural lands, especially by increasing salt deposition in soil, which results in soil salinity. Soil salinity is a major challenge to growth and reproduction among glycophytes (including all crop plants). Soil bacteria present in the rhizosphere and/or roots naturally protect plants from the adverse effects of soil salinity by reprogramming the stress induced physiological changes in plants. Bacteria can enrich the soil with major nutrients (nitrogen, phosphorus, and potassium) in a form easily available to plants and prevent the transport of excess sodium to roots (exopolysaccharides secreted by bacteria bind with sodium ions) for maintaining ionic balance and water potential in cells. Salinity also affects plant growth regulators and suppresses seed germination and root and shoot growth. Bacterial secretion of indole-3-acetic acid and gibberellins compensates for the salt-induced hormonal decrease in plants, and bacterial 1-aminocyclopropane-1-carboxylate (ACC) deaminase synthesis decreases ethylene production to stimulate plant growth. Furthermore, bacteria modulate the redox state of salinity-affected plants by enhancing antioxidants and polyamines, which leads to increased photosynthetic efficiency. Bacteria-induced accumulation of compatible solutes in stressed plants regulates plant cellular activities and prevents salt stress damage. Plant-bacterial interaction reprograms the expression of salt stress-responsive genes and proteins in salinity-affected plants, resulting in a precise stress mitigation metabolism as a defense mechanism. Soil bacteria increase the fertility of soil and regulate the plant functions to prevent the salinity effects in glycophytes. This review explains the current understanding about the physiological changes induced in glycophytes during bacterial interaction to alleviate the adverse effects of soil salinity stress. (C) 2017 Elsevier Masson SAS. All rights reserved.</P>

Bacillus oryzicola sp. nov., an Endophytic Bacterium Isolated from the Roots of Rice with Antimicrobial, Plant Growth Promoting, and Systemic Resistance Inducing Activities in Rice

정유진,MOHAMMADTOFAJJAL HOSSAIN,Ajmal Khan,김경현,전체옥,정영륜 한국식물병리학회 2015 Plant Pathology Journal Vol.31 No.2

Biological control of major rice diseases has been attempted in several rice-growing countries in Asia during the last few decades and its application using antagonistic bacteria has proved to be somewhat successful for controlling various fungal diseases in field trials. Two novel endophytic Bacillus species, designated strains YC7007 and YC7010T, with antimicrobial, plant growth-promoting, and systemic resistance-inducing activities were isolated from the roots of rice in paddy fields at Jinju, Korea, and their multifunctional activities were analyzed. Strain YC7007 inhibited mycelial growth of major rice fungal pathogens strongly in vitro. Bacterial blight and panicle blight caused by Xanthomonas oryzae pv. oryzae (KACC 10208) and Burkholderia glumae (KACC 44022), respectively, were also suppressed effectively by drenching a bacterial suspension (107 cfu/ml) of strain YC7007 on the rhizosphere of rice. Additionally, strain YC7007 promoted the growth of rice seedlings with higher germination rates and more tillers than the untreated control. The taxonomic position of the strains was also investigated. Phylogenetic analyses based on 16S rRNA gene sequences indicated that both strains belong to the genus Bacillus, with high similarity to the closely related strains, Bacillus siamensis KACC 15859T (99.67%), Bacillus methylotrophicus KACC 13105T (99.65%), Bacillus amyloliquefaciens subsp. plantarum KACC 17177T (99.60%), and Bacillus tequilensis KACC 15944T (99.45%). The DNA-DNA relatedness value between strain YC7010T and the most closely related strain, B. siamensis KACC 15859T was 50.4 ± 3.5%, but it was 91.5 ± 11.0% between two strains YC7007 and YC7010T, indicating the same species. The major fatty acids of two strains were anteiso-C15:0 and iso C15:0. Both strains contained MK-7 as a major respiratory quinone system. The G+C contents of the genomic DNA of two strains were 50.5 mol% and 51.2 mol%, respectively. Based on these polyphasic studies, the two strains YC7007 and YC7010T represent novel species of the genus Bacillus, for which the name Bacillus oryzicola sp. nov. is proposed. The type strain is YC7010T (= KACC 18228T). Taken together, our findings suggest that novel endophytic Bacillus strains can be used for the biological control of rice diseases.

Seed-borne endophytic Bacillus amyloliquefaciens RWL-1 produces gibberellins and regulates endogenous phytohormones of Oryza sativa

Shahzad, R.,Waqas, M.,Khan, A.L.,Asaf, S.,Khan, M.A.,Kang, S.M.,Yun, B.W.,Lee, I.J. Gauthier-Villars ; Elsevier Science Ltd 2016 Vol. No.

<P>Some microorganisms are adapted to an endophytic mode, living symbiotically with plants through vertical transmission in seeds. The role of plant growth-promoting endophytes has been well studied, but those of seed-associated endophytic bacteria are less understood. The current study aimed to isolate and identify bacterial endophytes associated with rice (Oryza sativa L. 'Jin so mi') seeds, their potential to produce gibberellins (GAs), and role in improving host-plant physiology. The isolated bacterial endophyte RWL-1 was identified as Bacillus amyloliquefaciens by using 16S rRNA sequencing and phylogenetic analysis. The pure culture of B. amyloliquefaciens RWL-1, supplied with deuterated internal standards, was subjected to gas chromatography and mass spectrometric selected ion monitoring (GC-MS/SIM) for quantification of GAs. Results showed the presence of GAs in various quantities (ng/mL) viz., GA(20) (17.88 +/- 4.04), GA(36) (5.75 +/- 2.36), GA(24) (5.64 +/- 2.46), GA(4) (1.02 +/- 0.16), GA(53) (0.772 +/- 0.20), GA(9) (0.12 +/- 0.09), GA(19) (0.093 +/- 0.13), GA(5) (0.08 +/- 0.04), GA(12) (0.014 +/- 0.34), and GA(8) (0.013 +/- 0.01). Since endogenous seed GAs are essential for prolonged seed growth and subsequent plant development, we used exogenous GA(3) as a positive control and water as a negative control for comparative analysis of the application of B. amyloliquefaciens RWL-1 to rice plants. The growth parameters of rice plants treated with endophytic bacterial cell application was significantly increased compared to the plants treated with exogenous GA3 and water. This was also revealed by the significant up-regulation of endogenous GA(1) (17.54 +/- 2.40 ng), GA(4) (310 +/- 5.41 ng), GA(7) (192.60 +/- 3.32 ng), and GA(9) (19.04 +/- 2.49 ng) as compared to results of the positive and negative control treatments. Rice plants inoculated with B. amyloliquefaciens RWL-1 exhibited significantly higher endogenous salicylic acid (1615.06 +/- 10.81 mu g), whereas endogenous abscisic acid (23.31 +/- 2.76 ng) and jasmonic acid (25.51 +/- 4.20 ng) were observed to be significantly lower in these inoculated plants than in those treated with exogenous GA3 and water. Results of the present study suggest that B. amyloliquefaciens RWL-1 has the ability to produce GAs and that its inoculation in seedlings can be beneficial to rice plants. Broader field trials should be conducted to determine its use as an alternative biofertilizer. (C) 2016 Elsevier Masson SAS. All rights reserved.</P>

Propionate Attenuates Growth of Oral Streptococci through Enhancing Methionine Biosynthesis

( Taehwan Park ),( Jintaek Im ),( A Reum Kim ),( Dongwook Lee ),( Sungho Jeong ),( Cheol-heui Yun ),( Seung Hyun Han ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.10

Oral streptococci are considered as an opportunistic pathogen associated with initiation and progression of various oral diseases. However, since the currently-available treatments often accompany adverse effects, alternative strategy is demanded to control streptococci. In the current study, we investigated whether short-chain fatty acids (SCFAs), including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), can inhibit the growth of oral streptococci. Among the tested SCFAs, NaP most potently inhibited the growth of laboratory and clinically isolated strains of Streptococcus gordonii under anaerobic culture conditions. However, the growth inhibitory effect of NaP on six different species of other oral streptococci was different depending on their culture conditions. Metabolic changes such as alteration of methionine biosynthesis can affect bacterial growth. Indeed, NaP enhanced intracellular methionine levels of oral streptococci as well as the mRNA expression level of methionine biosynthesis-related genes. Collectively, these results suggest that NaP has an inhibitory effect on the growth of oral streptococci, which might be due to alteration of methionine biosynthesis. Thus, NaP can be used an effective bacteriostatic agent for the prevention of oral infectious diseases caused by oral streptococci.

Predictive modeling of bacterial growth in ready-to-use salted napa cabbage (<i>Brassica pekinensis</i>) at different storage temperatures

Kim, H.W.,Lee, K.,Kim, S.H.,Rhee, M.S. Elsevier 2018 FOOD MICROBIOLOGY Vol.70 No.-

<P><B>Abstract</B></P> <P>The objectives of the current study were to investigate the fate of microbial indicators [aerobic plate counts (APC), total coliforms (TC), and lactic acid bacteria (LAB)] in commercial salted napa cabbages during storage conditions at different temperatures (5, 22, and 30 °C, for up to 72 h) and to develop a predictive growth model using the modified Gompertz equation to determine shelf life. Microbial population sizes (initial log CFU g<SUP>−1</SUP>: APC, 5.1; TC, 3.0; LAB, 3.7) remained stable at 5 °C, but rapidly increased by 2–4 log CFU g<SUP>−1</SUP> within 12 h at 22 and 30 °C; furthermore, the pH of salted napa cabbages decreased significantly (<I>P</I> < 0.05: initial pH 6.3; final pH 4.1–4.4) due to LAB fermentation. The pH showed a negative correlation with all bacterial groups and did not prevent the growth of TC during storage. According to the modified Gompertz model (R<SUP>2</SUP> ≧ 0.97), the highest <I>μ</I> <SUB>max</SUB> was observed for LAB at 30 °C [0.61 log CFU h<SUP>−1</SUP>], while the lowest was noted for TC at 5 °C [0.04 log CFU h<SUP>−1</SUP>]. Shelf-life was determined using APC (7.7 log CFU g<SUP>−1</SUP>) and LAB (6.0 log CFU g<SUP>−1</SUP>) limits; the microbiological acceptability period of salted napa cabbage was predicted to be 12.6 and 9.3 h at 22 and 30 °C, respectively. Thus, consumers should use the product within 12 h of storage at room temperature (more quickly in the summer (9 h)), or store it in a refrigerator. The presented research proposes a shelf-life modeling of commercial salted napa cabbages, which may be used as a scientific basis for product quality control and issuing appropriate guidance for consumer use at home.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A first-ever study of the microbiological shelf life of salted napa cabbage (SNC). </LI> <LI> Bacterial growth data fitted the modified Gompertz model, with R<SUP>2</SUP> ≧ 0.97. </LI> <LI> A decrease of pH on lactic acid fermentation did not inhibit total coliform growth. </LI> <LI> Consumers should use SNC within 12 and 9 h of storage at 22 and 30 °C, respectively. </LI> </UL> </P>

향신료와 야채류가 세균의 성장에 미치는 영향

이건일 ( G I Lee ) 대한임상검사과학회 1992 대한임상검사과학회지(KJCLS) Vol.24 No.1

This study was carried out to investigate the influence of food spices and vegetables, which are commonly available on the dining table everyday, on bacterial growth. Total 14 kinds of food spices and vegetables were .sampled in Kyungsan market in Kyungsan city. 7 strains of bacteria were used in this experiment as test strains which were 3 strains of Gram positive bacteria(Bacillus subtilis, Lactobacillus casei and Staphylococcus aureus) and Gram negative 4 strains(Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Shigella sp.). The results summerized were as follows : 1. The growth of all test strains except Pseudomonas aeruginosa was inhibited by water extracts of raw garlic with concentrations ranging 0.5% to 4.0%. 2. Bacillus subtilis, Klebsiella pneumoniae and Shigella sp. were not grown in tea with concentrations ranging 4.0% to 5.0%. 3. Water extracts of wormwood also interfered all strains growth except Bacillus subtilis of which inhibitory concentrations were ranged 2.0% to 10.0%. 4. In susceptibilities of test strains to NaCl solutions the most sensitive strain was Bacillus subtilis while Enterobacter aerogenes was showed strong resistance to each different concentration of this solution. Almost the growth of test strains except Enterobacter aerogenes were inhibited in over 4% of this solution. 5. Generally all of test strains were resisted to penicillin G whereas they all were susceptible only to streptomycin. Shigella sp. was markedly sensitive to all of antibiotics used in this experiment and MIC of this strain to them was 100 ,ug/ml while Pseudomonas aeruginosa was strongly tolerable to the all of antibiotics and its MIC to them was 400 + ,ug/ml. 6. Bacillus subtilis and Enterobacter aerogenes were able to grow until 85 ·c in gradually increasing temperature.