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Spiroplasma penaei sp. nov., associated with mortalities in Penaeus vannamei, Pacific white shrimp
Linda M Nunan1, Donald V Lightner1, Marietta A Oduori2
1Department of Veterinary Sciences and Microbiology, University of Arizona, Tucson, AZ 85721, USA.
Abstract:
A new bacterial strain, designated SHRIMP(T), isolated from the haemolymph of the Pacific white shrimp, Penaeus vannamei, was serologically distinct from other spiroplasmas. Cells of this strain were helical in form and variable in length. Examination by electron microscopy revealed wall-less cells delineated by a single cytoplasmic membrane. The organisms grew well in M1D media supplemented with 2 % NaCl. Strain SHRIMP(T) grew at temperatures of 20-37 degrees C, with optimum growth occurring at 28 degrees C. The strain catabolized glucose and hydrolysed arginine, but did not hydrolyse urea. The G+C content of the DNA was 29 +/-1 mol%. Strain SHRIMP(T) (=ATCC BAA-1082T=CAIM 1252T) is designated the type strain of a novel species, Spiroplasma penaei sp. nov., which represents a new subgroup (I-9) of the group I spiroplasmas.
Insights
A novel bacterial strain, Spiroplasma penaei (SHRIMP(T)), was identified in Pacific white shrimp. This distinct spiroplasma represents a new subgroup within group I spiroplasmas.
Area of Science:
- Microbiology
- Bacteriology
- Marine Biology
Background:
- Spiroplasmas are helical, wall-less bacteria that can cause disease in various hosts.
- The diversity and host specificity of spiroplasmas are not fully understood.
Purpose of the Study:
- To characterize a novel bacterial strain isolated from the Pacific white shrimp, Penaeus vannamei.
- To determine the taxonomic position of this new strain within the Spiroplasma genus.
Main Methods:
- Isolation and cultivation of the bacterial strain SHRIMP(T) from shrimp haemolymph.
- Morphological characterization using electron microscopy.
- Physiological and biochemical tests, including growth conditions and substrate utilization.
- DNA G+C content determination.
Main Results:
- Strain SHRIMP(T) exhibited helical morphology and wall-less cells.
- Optimal growth occurred at 28°C in M1D media with 2% NaCl.
- The strain catabolized glucose and hydrolyzed arginine but not urea.
- DNA G+C content was determined to be 29 ± 1 mol%.
Conclusions:
- Strain SHRIMP(T) is serologically distinct and represents a novel species, Spiroplasma penaei sp. nov.
- Spiroplasma penaei sp. nov. forms a new subgroup (I-9) within the group I spiroplasmas.
- This finding expands the known diversity of spiroplasmas and their association with marine invertebrates.
