{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T05:16:58Z","timestamp":1788412618778,"version":"build-2803163510"},"reference-count":25,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>Plant growth-promoting bacteria (PGPB) enhance plant development through mechanisms such as the production of indole-3-acetic acid (IAA). However, endophytic bacteria associated with aquatic plants, particularly watermeal (Wolffia spp.), remain poorly explored. This study investigated the potential of bacterially derived crude IAA extract for enhancing watermeal growth and accumulation of secondary metabolites in watermeal. This study isolated and screened endophytic bacteria from watermeal for IAA production, identifying Klebsiella variicola W1\/6 as the most efficient producer. Optimization using response surface methodology (RSM) revealed optimal conditions at pH 5.84, 5 days of incubation, and 10.63% (v\/v) inoculum size. Crude IAA extract significantly enhanced watermeal growth under both laboratory and greenhouse conditions. Notably, the combination of 0.5 ppm crude IAA extract with 50% chemical fertilizer produced growth comparable to that of the full fertilizer treatment, indicating reduced fertilizer requirement. These findings highlight the potential of bacterially derived IAA from K. variicola W1\/6 as a microbial biostimulant for sustainable aquatic plant cultivation.<\/jats:p>","DOI":"10.3390\/plants15172642","type":"journal-article","created":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T18:33:52Z","timestamp":1787942032000},"page":"2642","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Indole-3-Acetic Acid Production by Klebsiella variicola from Watermeal and Its Role in Enhancing Watermeal Growth"],"prefix":"10.3390","volume":"15","author":[{"given":"Tanaporn","family":"Ladthaisong","sequence":"first","affiliation":[{"name":"Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-6125-4281","authenticated-orcid":false,"given":"Thanawan","family":"Gateta","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1211-5457","authenticated-orcid":false,"given":"Wasan","family":"Seemakram","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3900-6453","authenticated-orcid":false,"given":"Urachart","family":"Kokaew","sequence":"additional","affiliation":[{"name":"Applied Intelligence and Data Analytics Laboratory, College of Computing, Khon Kaen University, Khon Kaen 40002, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nisachon","family":"Jangpromma","sequence":"additional","affiliation":[{"name":"Protein and Bio-Innovation Research Center for Sustainable Health (ProBISH), Khon Kaen University, Khon Kaen 40000, Thailand"},{"name":"Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40000, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2411-6863","authenticated-orcid":false,"given":"Sophon","family":"Boonlue","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand"},{"name":"Protein and Bio-Innovation Research Center for Sustainable Health (ProBISH), Khon Kaen University, Khon Kaen 40000, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1016\/j.foodchem.2016.08.116","article-title":"Nutritional Value of Duckweeds (Lemnaceae) as Human Food","volume":"217","author":"Appenroth","year":"2017","journal-title":"Food Chem."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Seephua, N., Boonarsa, P., Li, H., Thammapat, P., and Siriamornpun, S. (2025). Nutritional Composition and Bioactive Profiles of Farmed and Wild Watermeal (Wolffia globosa). Foods, 14.","DOI":"10.3390\/foods14101832"},{"key":"ref_3","unstructured":"Taiz, L., Zeiger, E., Moller, I.M., and Murphy, A. (2015). Plant Physiology and Development, Sinauer Associates. [6th ed.]."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"963401","DOI":"10.6064\/2012\/963401","article-title":"Plant Growth-Promoting Bacteria: Mechanisms and Applications","volume":"2012","author":"Glick","year":"2012","journal-title":"Scientifica"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1007\/s12892-017-0041-0","article-title":"IAA-Producing Klebsiella Variicola AY13 Reprograms Soybean Growth during Flooding Stress","volume":"20","author":"Kim","year":"2017","journal-title":"J. Crop Sci. Biotechnol."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Davies, P.J. (2010). Plant Hormones, Springer.","DOI":"10.1007\/978-1-4020-2686-7"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1111\/j.1574-6976.2007.00072.x","article-title":"Indole-3-Acetic Acid in Microbial and Microorganism-Plant Signaling","volume":"31","author":"Spaepen","year":"2007","journal-title":"FEMS Microbiol. Rev."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"571","DOI":"10.1023\/A:1026037216893","article-title":"Plant Growth Promoting Rhizobacteria as Biofertilizers","volume":"255","author":"Vessey","year":"2003","journal-title":"Plant Soil"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Lambers, H., Chapin, F.S., and Pons, T.L. (2008). Plant Physiological Ecology, Springer.","DOI":"10.1007\/978-0-387-78341-3"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1327","DOI":"10.1007\/s11274-011-0979-9","article-title":"Plant Growth-Promoting Rhizobacteria (PGPR): Emergence in Agriculture","volume":"28","author":"Bhattacharyya","year":"2012","journal-title":"World J. Microbiol. Biotechnol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1086\/417659","article-title":"The Dilemma of Plants: To Grow or Defend","volume":"67","author":"Herms","year":"1992","journal-title":"Q. Rev. Biol."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Agarwal, M., and Sheikh, M.B. (2025). Isolation and Functional Characterization of Endophytic Bacteria from Muscadine Grape Berries: A Microbial Treasure Trove. Cells, 14.","DOI":"10.3390\/cells14050369"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1029","DOI":"10.4014\/jmb.2402.02008","article-title":"Screening Plant Growth-Promoting Bacteria with Antimicrobial Properties for Upland Rice","volume":"34","author":"Khamsuk","year":"2024","journal-title":"J. Microbiol. Biotechnol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1128\/CVI.00270-07","article-title":"Preparation of Bacterial DNA Template by Boiling and Effect of Immunoglobulin G as an Inhibitor in Real-Time PCR for Serum Samples from Patients with Brucellosis","volume":"15","author":"Macias","year":"2008","journal-title":"Clin. Vaccine Immunol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"He, X., Yuan, H., Li, Y., and Yang, C. (2026). Endophytic Plant Growth Promoting Bacteria from Two Halophytes Improve Wheat Performance under Salt Stress. Front. Plant Sci., 17.","DOI":"10.3389\/fpls.2026.1658930"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1504\/IJBRA.2010.034072","article-title":"MEGA Biocentric Software for Sequence and Phylogenetic Analysis: A Review","volume":"6","author":"Sohpal","year":"2010","journal-title":"Int. J. Bioinform. Res. Appl."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e3230","DOI":"10.21769\/BioProtoc.3230","article-title":"Analysis of Indole-3-Acetic Acid (IAA) Production in Klebsiella by LC-MS\/MS and the Salkowski Method","volume":"9","author":"Gang","year":"2019","journal-title":"Bio-Protocol"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1007\/s10482-012-9838-4","article-title":"A Simple Method for Simultaneous RP-HPLC Determination of Indolic Compounds Related to Bacterial Biosynthesis of Indole-3-Acetic Acid","volume":"103","author":"Szkop","year":"2013","journal-title":"Antonie Leeuwenhoek"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e19730","DOI":"10.1016\/j.heliyon.2023.e19730","article-title":"Optimum Aquaculture and Drying Conditions for Wolffia arrhiza (L.) Wimn","volume":"9","author":"Prosridee","year":"2023","journal-title":"Heliyon"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1104\/pp.24.1.1","article-title":"Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris","volume":"24","author":"Arnon","year":"1949","journal-title":"Plant Physiol."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Siriwat, W., Ungwiwatkul, S., Unban, K., Laokuldilok, T., Klunklin, W., Tangjaidee, P., Potikanond, S., Kaur, L., and Phongthai, S. (2023). Extraction, Enzymatic Modification, and Anti-Cancer Potential of an Alternative Plant-Based Protein from Wolffia globosa. Foods, 12.","DOI":"10.3390\/foods12203815"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/S0021-9258(19)52451-6","article-title":"Protein measurement with the folin phenol reagent","volume":"193","author":"Lowry","year":"1951","journal-title":"J. Biol. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/j.scienta.2017.04.020","article-title":"Quality, Bioactive Compounds and Antioxidant Capacity of Selected Climacteric Fruits with Relation to Their Maturity","volume":"221","author":"Siriamornpun","year":"2017","journal-title":"Sci. Hortic."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"444","DOI":"10.1016\/j.seppur.2008.02.020","article-title":"Extraction of Flavonoids and Carotenoids from Thai Silk Waste and Antioxidant Activity of Extracts","volume":"62","author":"Prommuak","year":"2008","journal-title":"Sep. Purif. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/S0308-8146(01)00251-5","article-title":"An Investigation of Antioxidant Capacity of Fruits in Singapore Markets","volume":"76","author":"Leong","year":"2002","journal-title":"Food Chem."}],"container-title":["Plants"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/17\/2642\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T04:39:48Z","timestamp":1788410388000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/17\/2642"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,28]]},"references-count":25,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["plants15172642"],"URL":"https:\/\/doi.org\/10.3390\/plants15172642","relation":{},"ISSN":["2223-7747"],"issn-type":[{"value":"2223-7747","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,28]]}}}