Root-knot nematodes (Meloidogyne spp.) are plant parasites that cause serious economic damage by infecting over 2,000 plant species globally [1]. Second-stage juveniles of Meloidogyne spp. invade plant roots and produce galls, thereby disturbing the uptake of nutrients and water by the host plants [2]. The above-ground symptoms of host plants infected by Meloidogyne spp. may be similar to those observed in plants with root damage. As specific root-knot symptoms are not apparent above ground, it is difficult to determine the exact moment of outbreak in order to implement crop protection measures. With outdated nematode control methods, host plants could experience heavy root system damage, and this results in economic losses of over $100 billion worldwide [3].Among more than 100 Meloidogyne spp., four major species, namely, M. incognita, M. arenaria, M. javanica, and M. hapla are the most common species in agriculture in Korea [4]. These nematodes are problematic owing to their broad host range, high reproductivity, and endoparasitic characteristics [5,6]. Moreover, continuous cultivation of horticultural crops, such as oriental melon, red pepper, and tomato, makes it difficult to control these nematode species in greenhouses [4,7,8].Chemical nematicides are preferred for nematode control. Although promising as control agents, some have been banned over environmental concerns, residual issues, and toxicity to humans and livestock. Alternative control methods using antagonistic microorganisms such as fungi and bacteria are being investigated [9][10][11]. As antagonistic microorganisms are not sufficiently efficacious on their own [12], it is necessary to develop a strategy that integrates different control methods to improve the control efficacy.Lactic acid bacteria (LAB) play a key role in the production of various fermented meat, fish, and dairy products, and kimchi (Korean traditional fermented cabbage) [13]. They are gram-positive bacteria and are divided into two metabolic categories, homofermentative and heterofermentative, based on their metabolism. In general, homofermentative LAB, such as Lactiplantibacillus spp., Lactococcus spp., and Pediococcus spp., are more acid tolerant than heterofermentative LAB, including Leuconostoc spp. and Weissella spp. The antagonistic activities of homofermentative LAB have been reported against phytopathogenic microorganisms and root-knot nematodes, via the production of organic acids in carbohydrate fermentation [11,14,15].Copper sulfate has been found to be directly toxic to root-knot nematodes in a laboratory test, and it indirectly Lactic acid bacteria (LAB) exert antagonistic activity against root-knot nematodes, mainly by producing organic acids via carbohydrate fermentation. However, they have not yet been used for root-knot nematode (Meloidogyne incognita) control owing to a lack of economic feasibility and effectiveness. In this study, we aimed to isolate organic acid-producing LAB from kimchi (Korean traditional fermented cabbage) and evaluated their nematicidal a...
