Name: an improved chemotaxis assay for the rapid identification of rhizobacterial chemoattractants in root exudates
Uploaded: 2022-03-25T13:30:00
Description: Watch this Scientific Journal Video about An Improved Chemotaxis Assay for the Rapid Identification of Rhizobacterial Chemoattractants in Root Exudates at JoVE.com

This work was supported by the National Natural Science Foundation of China (Nos. 31870493), the Key Research and Development Projects in Heilongjiang, China (GA21B007), and the Basic Research Fees of Universities in Heilongjiang Province, China (No. 135409103).

1. Materials and equipment
NOTE: Bacillus altitudinis LZP02 (CP075052) was isolated from the rhizosphere of rice in northeast China12,13 for this study.
<ol>
	<li>Culture B. altitudinis LZP02 in Luria-Bertani (LB) medium (peptone, 10 g L-1; NaCl, 8 g L-1 and yeast extract, 5 g L-1) for 10 h. Collect cells by centrifugation at 9,569 x g for 2 min at ...

<ol>
	<li>Belas, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilms,+flagella,+and+mechanosensing+of+surfaces+by+bacteria.">Biofilms, flagella, and mechanosensing of surfaces by bacteria.</a> Trends in Microbiology. 22 (9), 517-527 (2014).</li><li>Haichar, Z., Santaella, C., Heulin, T., Achouak, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Root+exudates+mediated+interactions+belowground.">Root exudates mediated interactions belowground.</a> Soil Biology and Biochemistry. 77 (7), 69-80 (2014).</li><li>Zhang, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+different+plant+root+exudates+and+their+organic+acid+components+on+chemotaxis,+biofilm+formation+and+colonization+by+beneficial+rhizosphere-associated+bacterial+strains.">Effects of different plant root exudates and their organic acid components on chemotaxis, biofilm formation and colonization by beneficial rhizosphere-associated bacterial strains.</a> Plant and Soil. 374 (1-2), 689-700 (2014).</li><li>Zhang, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+transcriptomic+analysis+of+the+plant-beneficial+rhizobacterium+Bacillus+amyloliquefaciens+SQR9+during+enhanced+biofilm+formation+regulated+by+maize+root+exudates.">Whole transcriptomic analysis of the plant-beneficial rhizobacterium Bacillus amyloliquefaciens SQR9 during enhanced biofilm formation regulated by maize root exudates.</a> BMC Genomics. 16 (1), 685 (2015).</li><li>Lui, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induced+root-secreted+D-galactose+functions+as+a+chemoattractant+and+enhances+the+biofilm+formation+of+Bacillus+velezensis+SQR9+in+an+mcpa-dependent+manner.">Induced root-secreted D-galactose functions as a chemoattractant and enhances the biofilm formation of Bacillus velezensis SQR9 in an mcpa-dependent manner.</a> Applied Microbiology and Biotechnology. 104 (17), 785-797 (2020).</li><li>Vora, S. M., Joshi, P., Belwalkar, M., Archana, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Root+exudates+influence+chemotaxis+and+colonization+of+diverse+plant+growth-promoting+rhizobacteria+in+the+Cajanus+cajan+-+Zea+mays+intercropping+system.">Root exudates influence chemotaxis and colonization of diverse plant growth-promoting rhizobacteria in the Cajanus cajan - Zea mays intercropping system.</a> Rhizosphere. 18 (12), 100331 (2021).</li><li>Sampedro, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+halophyte+root+exudates+and+their+components+on+chemotaxis,+biofilm+formation+and+colonization+of+the+halophilic+bacterium+halomonas+anticariensis+FP35T.">Effects of halophyte root exudates and their components on chemotaxis, biofilm formation and colonization of the halophilic bacterium halomonas anticariensis FP35T.</a> Microorganisms. 8 (4), 575 (2020).</li><li>Liu, X. L., Raza, W., Ma, J. H., Huang, Q. W., Shen, Q. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dual+role+amino+acid+from+sesbania+rostrata+seed+exudates+in+the+chemotaxis+response+of+Azorhizobium+caulinodans+ORS571.">A dual role amino acid from sesbania rostrata seed exudates in the chemotaxis response of Azorhizobium caulinodans ORS571.</a> Molecular Plant-Microbe Interactions. 32 (9), 1134-1147 (2019).</li><li>Ling, N., Raza, W., Ma, J. H., Huang, Q. W., Shen, Q. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+and+role+of+organic+acids+in+watermelon+root+exudates+for+recruiting+Paenibacillus+polymyxa+SQR-21+in+the+rhizosphere.">Identification and role of organic acids in watermelon root exudates for recruiting Paenibacillus polymyxa SQR-21 in the rhizosphere.</a> European Journal of Soil Biology. 47 (6), 374-379 (2011).</li><li>Rudrappa, T., Czymmek, K. J., Pare, P. W., Bais, H. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Root-secreted+malic+acid+recruits+beneficial+soil+bacteria.">Root-secreted malic acid recruits beneficial soil bacteria.</a> Plant Physiology. 148 (3), 1547-1556 (2008).</li><li>Shen, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacterial+chemotaxis+on+Slipchip.">Bacterial chemotaxis on Slipchip.</a> Lab on a Chip. 14 (16), 3074-3080 (2014).</li><li>Liu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacillus+pumilus+LZP02+promotes+rice+root+growth+by+improving+carbohydrate+metabolism+and+phenylpropanoid+biosynthesis.">Bacillus pumilus LZP02 promotes rice root growth by improving carbohydrate metabolism and phenylpropanoid biosynthesis.</a> Molecular Plant-Microbe Interactions. 33 (10), 1222-1231 (2020).</li><li>Goswami, M., Deka, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+a+novel+rhizobacteria+having+multiple+plant+growth+promoting+traits+and+antifungal+activity+against+certain+phytopathogens.">Isolation of a novel rhizobacteria having multiple plant growth promoting traits and antifungal activity against certain phytopathogens.</a> Microbiological Research. 240, 126516 (2020).</li><li>Kaiira, M., Chemining'Wa, G., Ayuke, F., Baguma, Y., Nganga, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Profiles+of+compounds+in+root+exudates+of+rice,+cymbopogon,+desmodium,+mucuna+and+maize.">Profiles of compounds in root exudates of rice, cymbopogon, desmodium, mucuna and maize.</a> Journal of Agricultural Sciences Belgrade. 64 (4), 399-412 (2019).</li><li>Shi, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+rice+root+exudates+and+strain+combination+on+biofilm+formation+of+Paenibacillus+polymyxa+and+Paenibacillus+macerans.">Effect of rice root exudates and strain combination on biofilm formation of Paenibacillus polymyxa and Paenibacillus macerans.</a> African Journal of Microbiology Research. 6 (13), 3343-3347 (2012).</li><li>Lee, H. W., Ghimire, S. R., Shin, D. H., Lee, I. J., Kim, K. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allelopathic+effect+of+the+root+exudates+of+K21,+a+potent+allelopathic+rice.">Allelopathic effect of the root exudates of K21, a potent allelopathic rice.</a> Weed Biology and Management. 8 (2), 85-90 (2008).</li><li>Belimov, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rhizobacteria+that+produce+auxins+and+contain+1-amino-cyclopropane-1-carboxylic+acid+deaminase+decrease+amino+acid+concentrations+in+the+rhizosphere+and+improve+growth+and+yield+of+well-watered+and+water-limited+potato+(Solanum+tuberosum).">Rhizobacteria that produce auxins and contain 1-amino-cyclopropane-1-carboxylic acid deaminase decrease amino acid concentrations in the rhizosphere and improve growth and yield of well-watered and water-limited potato (Solanum tuberosum).</a> Annals of Applied Biology. 167 (1), 11-25 (2015).</li><li>Ankati, S., Podile, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolites+in+the+root+exudates+of+groundnut+change+during+interaction+with+plant+growth+promoting+rhizobacteria+in+a+strain-specific+manner.">Metabolites in the root exudates of groundnut change during interaction with plant growth promoting rhizobacteria in a strain-specific manner.</a> Journal of Plant Physiology. 243, 153057 (2019).</li><li>Gordillo, F., Chavez, F., Jerez, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motility+and+chemotaxis+of+Pseudomonas+sp.+B4+towards+polychlorobiphenyls+and+chlorobenzoates.">Motility and chemotaxis of Pseudomonas sp. B4 towards polychlorobiphenyls and chlorobenzoates.</a> FEMS Microbiology Ecology. 60 (2), 322-328 (2007).</li><li>Bais, H. P., Weir, T. L., Perry, L. G., Gilroy, S., Vivanco, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+root+exudates+in+rhizosphere+interactions+with+plants+and+other+organisms.">The role of root exudates in rhizosphere interactions with plants and other organisms.</a> Annual Review of Plant Biology. 57, 233-266 (2006).</li><li>Badri, D. V., Vivanco, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+and+function+of+root+exudates.">Regulation and function of root exudates.</a> Plant Cell Environment. 32 (6), 666-681 (2009).</li><li>Badri, D. V., Weir, T. L., Lelie, D., Vivanco, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rhizosphere+chemical+dialogues:+plant-microbe+interactions.">Rhizosphere chemical dialogues: plant-microbe interactions.</a> Curr Opin Biotech. Current Opinion in Biotechnology. 20 (6), 642-650 (2009).</li><li>Kamilova, F., Kravchenko, L. V., Shaposhnikov, A. I., Makarova, N., Lugtenberg, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+the+tomato+pathogen+Fusarium+oxysporum+f.+sp.+radicis-lycopersici+and+of+the+biocontrol+bacterium+Pseudomonas+fluorescens+WCS365.">Effects of the tomato pathogen Fusarium oxysporum f. sp. radicis-lycopersici and of the biocontrol bacterium Pseudomonas fluorescens WCS365.</a> Molecular Plant-Microbe Interactions. 19 (10), 1121-1126 (2006).</li><li>Kamilova, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organic+acids,+sugars,+and+L-tryptophane+in+exudates+of+vegetables+growing+on+stonewool+and+their+effects+on+activities+of+rhizosphere+bacteria.">Organic acids, sugars, and L-tryptophane in exudates of vegetables growing on stonewool and their effects on activities of rhizosphere bacteria.</a> Molecular Plant-Microbe Interactions. 19 (3), 250-256 (2006).</li><li>Badri, D. V., Vivanco, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+and+function+of+root+exudates.">Regulation and function of root exudates.</a> Plant Cell Environment. 32 (6), 666-681 (2009).</li><li>Hao, W. Y., Ren, L. X., Ran, W., Shen, Q. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allelopathic+effects+of+root+exudates+from+watermelon+and+rice+plants+on+Fusarium+oxysporum+f.sp.+Niveum.">Allelopathic effects of root exudates from watermelon and rice plants on Fusarium oxysporum f.sp. Niveum.</a> Plant and Soil. 336 (1-2), 485-497 (2010).</li><li>Hao, Z. P., Wang, Q., Christie, P., Li, X. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allelopathic+potential+of+watermelon+tissues+and+root+exudates.">Allelopathic potential of watermelon tissues and root exudates.</a> Scientia Horticulturae. 112 (3), 315-320 (2007).</li></ol>

Increasing research indicates that plant-bacteria interactions mainly occur in the rhizosphere and are influenced by root exudates20,21,22,23,24. Plant root exudates include a diverse array of primary metabolites, including phenolic acids, organic acids and amino acids as well as more complex secondary compounds25,<sup class=...

Chemotaxis is important for colonization of plant growth-promoting rhizobacterial (PGPR) on roots and for understanding plant-microbe interactions1. A class of low molecular weight compounds (chemoattractants) in plant root exudates induce the chemotactic movement of PGPR to the rhizosphere2. Malic acid, citric acid, and other components in the root exudates stimulate chemotaxis of Bacillus strains3. For example, glucose, citric acid, and fumaric acid in maize root exudates recruit bacteria&#160;to the root surface4. D-galactose, which&#160;is derived from root exudates,induces the chemotaxis of Bacillus velezensis SQR95. Organic acids, including fumarate, malic acid, and succinate, influence chemotaxis and colonization of various PGPR in the Cajanus cajan - Zea mays intercropping system6. Oleanolic acid in rice root exudates, acts as a chemoattractant for the strain FP357. Other plant exudates (including histidine, arginine, and aspartate) can play a crucial role in the chemotactic response of bacteria8. Plant exudates function as a signal to direct the movement of bacteria, which is the first step during rhizosphere colonization. Plant colonization by PGPR is a process of enormous relevance, as PGPR are beneficial for the plant host.
Many methods have been used for analyzing bacterial chemotaxis. The swimming plate method is one of the methods described previously9. In this method, plates were made with a semisolid medium. A chemotactic buffer containing agar (1.0%, w/v) was added to the plate. The buffer is heated, and then mixed with the chemoattractant. Then, 8 &#181;L of bacteria suspension was added dropwise to the middle of the plate and the plate was placed in an incubator at 28 &#176;C. The plate was regularly observed and photographed. However, the experimental cycle of the swimming plate method was very long. In the capillary-like method10, a pipette tip serves as a chamber for holding 100 &#181;L of bacterial suspension. 1 mL syringe needle was used as a capillary. A syringe needle containing chemoattractants with different concentration gradients was inserted into the 100 &#181;L pipette tip. After incubation at room temperature for 3 h, the syringe needle was removed, the content was diluted and plated on the medium. The bacterial accumulation in the syringe was represented by colony-forming units (CFUs) in the plates. However, the experimental error within replicates for the capillary-like method was large. Another method used a microfluidic SlipChip device11. Briefly, bovine serum albumin (BSA) solution was injected into all channels and removed using a vacuum. The solutions containing different chemoattractants (1 mM concentration for qualitative detection only), bacterial cells suspended in phosphate-buffered saline and phosphate buffered saline buffer (negative control) were added to the top, middle, and bottom microwells, respectively. Incubation was then performed in a dark environment at room temperature for 30 min. The bacterial cells were then detected in the microwells. The microfluidic SlipChip device, however, was expensive. Therefore, each of the methods described above had advantages and disadvantages.
We established an improved chemotaxis assay for the rapid identification of rhizobacterial chemoattractants in root exudates using sterile glass slides without complicated steps. In this study, through multiple comparisons of experimental results, the method overcame multiple shortcomings of traditional bacterial chemotaxis methods. The method reduced the error of plate counting and shortened the experimental cycle. Therefore, if used to identify a chemoattractant substance, this new method can save 2-3 days and reduce the cost of experimental materials.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2,5-dihydroxybenzoic acid</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>490-79-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetonitrile</td>
			<td>CNW Technologies</td>
			<td>75-05-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium acetate</td>
			<td>CNW Technologies</td>
			<td>631-61-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Caffeic acid</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>331-39-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>Heraeus Fresco17</td>
			<td></td>
		</tr>
		<tr>
			<td>Citric acid</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>77-92-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Clean bench</td>
			<td>Shanghai Boxun Industrial Co., Ltd.</td>
			<td>BJ-CD</td>
			<td></td>
		</tr>
		<tr>
			<td>Ferulic acid</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>1135-24-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Formic acid</td>
			<td>CNW Technologies</td>
			<td>64-18-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Fructose</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>57-48-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Galactose</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>59-23-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>56-40-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Grinding Mill</td>
			<td>Shanghai Jingxin Industrial Development 
			Co., Ltd.</td>
			<td>JXFSTPRP-24</td>
			<td></td>
		</tr>
		<tr>
			<td>Histidine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>71-00-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Internal standard: 2-Chloro-L-phenylalanine</td>
			<td>Shanghai Hengbai Biotech C.,Ltd.</td>
			<td>103616-89-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Leucine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>61-90-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Malic acid</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>6915-15-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Mannose</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>3458-28-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Mass Spectrometer</td>
			<td>Thermo Fisher Scientific</td>
			<td>Q Exactive Focus</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>CNW Technologies</td>
			<td>67-56-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical Microscope</td>
			<td>Olympus</td>
			<td>BX43</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenylalanine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>63-91-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Proline</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>147-85-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Scales</td>
			<td>Sartorius</td>
			<td>BSA124S-CW</td>
			<td></td>
		</tr>
		<tr>
			<td>Serine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>56-45-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Threonine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>72-19-5</td>
			<td></td>
		</tr>
		<tr>
			<td>UHPLC</td>
			<td>Agilent</td>
			<td>1290 UHPLC</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasound Instrument</td>
			<td>Shenzhen Leidebang Electronics 
			Co., Ltd.</td>
			<td>PS-60AL</td>
			<td></td>
		</tr>
		<tr>
			<td>Valine</td>
			<td>Beijing InnoChem Science &#38; Technology C.,Ltd.</td>
			<td>7004-03-7</td>
			<td></td>
		</tr>
	</tbody>
</table>

an improved chemotaxis assay for the rapid identification of rhizobacterial chemoattractants in root exudates

Chemotaxis identification is very important for the research and application of rhizosphere growth-promoting bacteria. We established a straightforward method to quickly identify the chemoattractants that could induce the chemotactic movement of rhizosphere growth-promoting bacteria on sterile glass slides via simple steps. Bacteria solution (OD600 = 0.5) and sterile chemoattractant aqueous solution were added dropwise on the glass slide at an interval of 1 cm. An inoculating loop was used to connect the chemoattractant aqueous solution to the bacterial solution. The slide was kept at room temperature for 20 min on the clean bench. Finally, the chemoattractant aqueous solution was collected for bacterial counting and microscopic observation. In this study, through multiple comparisons of experimental results, the method overcame multiple shortcomings of traditional bacterial chemotaxis methods. The method reduced the error of plate counting and shortened the experimental cycle. For the identification of chemoattractant substances, this new method can save 2-3 days compared to the traditional method. Additionally, this method allows any researcher to systematically complete a bacterial chemotaxis experiment within 1-2 days. The protocol can be considered a valuable resource for understanding plant-microbe interactions.

A total of 584 and 937 known metabolites were detected in the positive and negative ion indices, respectively. Previous studies have shown that chemoattractants are typically organic acids, amino acids, and carbohydrates17,18.
In this study, 16 kinds of chemoattractants from the LC-MS studies in the rice rhizosphere exudates were selected for subsequent experiments (Table 1). Using the swimming plate method, we screene...

Watch this Scientific Journal Video about An Improved Chemotaxis Assay for the Rapid Identification of Rhizobacterial Chemoattractants in Root Exudates at JoVE.com

An Improved Chemotaxis Assay for the Rapid Identification of Rhizobacterial Chemoattractants in Root Exudates

Here, we present an improved chemotaxis assay protocol. The goal of this protocol is to reduce the steps and costs of traditional bacterial chemotaxis methods and to serve as a valuable resource for understanding plant-microbe interactions.

Chemotaxis identification is very important for the research and application of rhizosphere growth-promoting bacteria. We established a straightforward ...

Research

JoVE Journal

Biology

C. elegans Chemotaxis Assay

C. elegans Chemotaxis Assay

Many organisms use chemotaxis to seek out food sources, avoid noxious substances, and find mates.  Caenorhabditis elegans has impressive chemotaxis ...

An Improved Method for Accurate and Rapid Measurement of Flight Performance in Drosophila

An Improved Method for Accurate and Rapid Measurement of Flight Performance in Drosophila

Drosophila has proven to be a useful model system for analysis of behavior, including flight. The initial flight tester involved dropping flies into an ...

Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae

Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae

Determining the mode of action of bioactive chemicals is of interest to a broad range of academic, pharmaceutical, and industrial scientists. ...

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and ...

Filtration Isolation of Nucleic Acids:  A Simple and Rapid DNA Extraction Method

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad ...

Hybrid-Cut: An Improved Sectioning Method for Recalcitrant Plant Tissue Samples

Maintaining plant section integrity is essential for studying detailed anatomical structures at the cellular, tissue, or even organ level. However, some ...

Plant Promoter Analysis: Identification and Characterization of Root Nodule Specific Promoter in the Common Bean

The upstream sequences of gene coding sequences are termed as promoter sequences. Studying the expression patterns of promoters are very significant in ...

Plant-Microbe Interaction: Transcriptional Response of Bacillus Mycoides to Potato Root Exudates

Plant-Microbe Interaction: Transcriptional Response of Bacillus Mycoides to Potato Root Exudates

Beneficial plant-associated bacteria play an important role in promoting growth and preventing disease in plants. The application of plant ...

SA-&#946;-Galactosidase-Based Screening Assay for the Identification of Senotherapeutic Drugs

SA-ÃƒÆ’Ã…Â½Ãƒâ€šÃ‚Â²-Galactosidase-Based Screening Assay for the Identification of Senotherapeutic Drugs

Cell senescence is one of the hallmarks of aging known to negatively influence a healthy lifespan. Drugs able to kill senescent cells specifically in cell ...

Rapid In Vivo Fixation and Isolation of Translational Complexes from Eukaryotic Cells

Rapid In Vivo Fixation and Isolation of Translational Complexes from Eukaryotic Cells

Rapid responses involving fast redistribution of messenger(m)RNA and alterations of mRNA translation are pertinent to ongoing homeostatic adjustments of ...