Characterization of a Deep-Branching Heterolobosean, Pharyngomonas turkanaensis n. sp., Isolated from a Non-Hypersaline Habitat, and Ultrastructural Comparison of Cysts and Amoebae Among Pharyngomonas Strains

被引:14
|
作者
Park, Jong Soo [1 ,2 ]
Simpson, Alastair G. B. [3 ,4 ]
机构
[1] Kyungpook Natl Univ, Sch Earth Syst Sci, Dept Oceanog, Daegu, South Korea
[2] Kyungpook Natl Univ, Sch Earth Syst Sci, Kyungpook Inst Oceanog, Daegu, South Korea
[3] Dalhousie Univ, Dept Biol, Halifax, NS B3H 4R2, Canada
[4] Canadian Inst Adv Res, Program Integrated Microbial Divers, Toronto, ON, Canada
基金
加拿大自然科学与工程研究理事会; 新加坡国家研究基金会;
关键词
Amoeboflagellate; electron microscopy; excavata; halophile; halotolerant; protist; protozoa; taxonomy; VAHLKAMPFIID AMEBA; LIFE-CYCLE; GEN; NOV; FLAGELLATE; EVOLUTIONARY; PERCOLOMONAS; MORPHOLOGY; NAEGLERIA; EXCAVATA; LINEAGE;
D O I
10.1111/jeu.12260
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
An unusual heterolobosean amoeba, isolate LO, was isolated recently from a sample with a salinity of similar to 4 parts per thousand, from Lake Turkana in East Africa. 18S rDNA phylogenies confirm that isolate LO branches among halophilic amoeboflagellates assigned to Pharyngomonas. We examined the ultrastructure of the amoeba and cyst stages of isolate LO, as well as the amoebae and cysts of Pharyngomonas kirbyi (isolates AS12B and SD1A). The amoebae of all three isolates lacked discrete dictyosomes and had discoidal/flattened mitochondrial cristae, but the mitochondria were not enrobed by rough endoplasmic reticulum. The cysts of all three isolates showed a thick, bipartite cyst wall, and lacked cyst pores. The cysts of isolate LO were distinct in that the ectocyst was very loose-fitting, and could contain "crypts". No flagellate form of isolate LO has been observed to date, and a salinity-for-growth experiment showed that isolate LO can grow at 15-100 parts per thousand salinity, indicating that it is halotolerant. By contrast, other studied Pharyngomonas isolates are amoeboflagellates and true halophiles. Therefore, we propose isolate LO as a new species, Pharyngomonas turkanaensis n. sp. It is possible that P. turkanaensis descended from halophilic ancestors, and represents a secondary reestablishment of a physiology adapted for moderate salinity.
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页码:100 / 111
页数:12
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