Open AccessEnvironmental Free-Living Amoebae Isolated from Soil in Khon Kaen, Thailand, Antagonize Burkholderia pseudomallei
Author(s) -
Parumon Noinarin,
Pisit Chareonsudjai,
Pinich Wangsomnuk,
Surasakdi Wongratanacheewin,
Sorujsiri Chareonsudjai
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0167355
Subject(s) - burkholderia pseudomallei , melioidosis , microbiology and biotechnology , biology , acanthamoeba , protozoa , bacteria , genetics
Presence of Burkholderia pseudomallei in soil and water is correlated with endemicity of melioidosis in Southeast Asia and northern Australia. Several biological and physico-chemical factors have been shown to influence persistence of B . pseudomallei in the environment of endemic areas. This study was the first to evaluate the interaction of B . pseudomallei with soil amoebae isolated from B . pseudomallei -positive soil site in Khon Kaen, Thailand. Four species of amoebae, Paravahlkampfia ustiana , Acanthamoeba sp., Naegleria pagei , and isolate A-ST39-E1, were isolated, cultured and identified based on morphology, movement and 18S rRNA gene sequence. Co-cultivation combined with a kanamycin-protection assay of B . pseudomallei with these amoebae at MOI 20 at 30°C were evaluated during 0–6 h using the plate count technique on Ashdown’s agar. The fate of intracellular B . pseudomallei in these amoebae was also monitored by confocal laser scanning microscopy (CLSM) observation of the CellTracker ™ Orange- B . pseudomallei stained cells. The results demonstrated the ability of P . ustiana , Acanthamoeba sp. and isolate A-ST39-E1 to graze B . pseudomallei . However, the number of internalized B . pseudomallei substantially decreased and the bacterial cells disappeared during the observation period, suggesting they had been digested. We found that B . pseudomallei promoted the growth of Acanthamoeba sp. and isolate A-ST39-E1 in co-cultures at MOI 100 at 30°C, 24 h. These findings indicated that P . ustiana , Acanthamoeba sp. and isolate A-ST39-E1 may prey upon B . pseudomallei rather than representing potential environmental reservoirs in which the bacteria can persist.