title: Effects of associated bacteria on the pathogenicity and reproduction of the insect-parasitic nematode Rhabditis blumi (Nematoda: Rhabditida).
abstract: Three bacteria, Alcaligenes faecalis , Flavobacterium sp., and Providencia vermicola , were isolated from dauer juveniles of Rhabditis blumi . The pathogenic effects of the bacteria against 4th instar larvae of Galleria mellonella were investigated. Providencia vermicola and Flavobacterium sp. showed 100% mortality at 48 h after haemocoelic injection, whereas A. faecalis showed less than 30% mortality. Dauer juveniles showed 100% mortality against G. mellonella larvae, whereas axenic juveniles, which do not harbor associated bacteria, exhibited little mortality. All of the associated bacteria were used as a food source for nematode growth, and nematode yield differed with bacterial species. Among the bacterial species, P. vermicola was most valued for nematode yield, showing the highest yield of 5.2 × 10(4) nematodes/mL in the plate. In bacterial cocultures using two of the three associated bacteria, one kind stimulated the other. The highest total bacterial yield of 12.6 g/L was obtained when the inoculum ratio of P. vermicola to A. faecalis was 10:1. In air-lift bioreactors, the nematode growth rate increased with an increasing level of dissolved oxygen. The maximum nematode yield of 1.75 × 10(5) nematodes/mL was obtained at 192 h with an aeration rate of 6 vvm.
authors.affiliation: Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Shinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea.
authors.forename: Hae Woong
authors.initials: HW
authors.lastname: Park
authors.forename: Yong Ook
authors.initials: YO
authors.lastname: Kim
authors.forename: Jae-Seok
authors.initials: JS
authors.lastname: Ha
authors.forename: Sung Hun
authors.initials: SH
authors.lastname: Youn
authors.forename: Hyeong Hwan
authors.initials: HH
authors.lastname: Kim
authors.forename: Anwar L
authors.initials: AL
authors.lastname: Bilgrami
authors.forename: Chul Soo
authors.initials: CS
authors.lastname: Shin
mesh_terms: D000818:Animals; D001419:Bacteria / Q000254:growth & development* / Q000302:isolation & purification / Q000472:pathogenicity; D001517:Coleoptera / Q000382:microbiology / Q000469:parasitology; D005417:Flavobacterium / Q000254:growth & development / Q000302:isolation & purification; D007313:Insecta / Q000382:microbiology / Q000469:parasitology*; D007814:Larva / Q000382:microbiology / Q000502:physiology; D007915:Lepidoptera / Q000382:microbiology / Q000469:parasitology; D011532:Providencia / Q000254:growth & development / Q000302:isolation & purification; D012098:Reproduction / Q000502:physiology; D017172:Rhabditoidea / Q000382:microbiology / Q000472:pathogenicity* / Q000502:physiology; D013559:Symbiosis