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Jeong Hwa Kim, Jin Kyu Park and Jae Kwon Lee

Abstract

Nosemosis is one of the most common protozoan diseases of adult bees (Apis mellifera). Nosemosis is caused by two species of microsporidia; Nosema apis and Nosema ceranae. Nosema ceranae is potentially more dangerous because it has the ability to infect multiple cell types, and it is now the predominant microsporidian species in A. mellifera. In this study, we identified two anti-nosemosis plants, Aster scaber and Artemisia dubia, which reduced the spore development of N. ceranae in spore-infected cells. The most important aspect of our results was that our treatment was effective at non-toxic concentrations. Anti-nosemosis activities of both plants were revealed in honey bee experiments. Specifically, a mixed extract of both A. scaber and A. dubia showed stronger activity than treatment with each single extract alone. Although the mechanisms of action of A. scaber and A. dubia against N. ceranae are still unclear, our results suggest new medicaments and therapeutic methods to control N. ceranae infection.

Open access

Jae Kwon Lee, Jeong Hwa Kim, Mina Jo, Balamurugan Rangachari and Jin Kyu Park

Abstract

In our previous study, we demonstrated that the ethanol extracts of Artemisia dubia (A. dubia) and Aster scaber (A. scaber) have anti-nosemosis activity. In our present study, we intend to establish the anti-nosemosis activity of aqueous, ethyl acetate (EA), and butanol (BuOH) extracts of A. dubia and A. scaber. In order to determine the optimal dose, we performed both in vitro and in vivo toxicity for all the extracts and also carried out anti-nosemosis experiments. Although all of the extracts (aqueous, EA, and BuOH) showed in vitro and in vivo anti-nosemosis activity in a dose-dependent manner, the aqueous extracts of A. dubia and A. scaber showed more potent anti-nosemosis activity than the EA and BuOH extracts. Moreover, an aqueous extract of A. dubia + A. scaber demonstrated stronger anti-nosemosis activity compared with the aqueous extracts of either A. dubia or A. scaber alone. Although the main ingredients in A. dubia and A. scaber remain unclear, our results suggest that the active components of A. dubia and A. scaber could dissolve in the aqueous fraction.

Open access

Changhoon Park, Jiwoon Jeong, Kyuhyung Choi, Jae Chul Lee, Oh Sung Kwon, Sung-Hoon Kim and Chanhee Chae

Abstract

The objective of this study was to assess cell-free fermented culture broth of 9 Lactobacillus plantarum strains as antibiotic alternatives for the inhibition of in vitro growth of enterotoxigenic Escherichia coli (ETEC) and Shiga toxin-producing E. coli (STEC) isolated from postweaning pigs with colibacillosis and edema disease in 2014. A total of 10 ETEC and 5 STEC strains isolated from postweaning pigs were tested in antimicrobial susceptibility tests. ETEC and STEC strains used in this study possessed at least one of fimbrial, enterotoxin, and Shiga-toxin genes when tested by polymerase chain reaction. Among 9 L. plantarum strains tested, 3 strains (Lp 2-05, 2-06, and 1-03) showed inhibitory activity of in vitro growth against 10 ETEC strains (100%) and 7 strains (Lp 6-13, 3-06, 3-05, 7-01, 2-06, 1-03, and 6-05) showed inhibitory activity of in vitro growth against 5 STEC strains (100%). Three strains (Lp 3-05, 2-06, and 1-03) showed inhibitory activity of in vitro growth against 10 ETEC (100%) and 5 STEC (100%) strains. The results of this study show the inhibitory activity of cell-free fermented culture broth of L. plantarum against ETEC and STEC isolated from postweaning pigs with colibacillosis and edema disease.