Indigenous microflora and opportunistic pathogens of the freshwater zebra mussel, Dreissena polymorpha

TY - JOUR

T1 - Indigenous microflora and opportunistic pathogens of the freshwater zebra mussel, Dreissena polymorpha

AU - Gu, Ji Dong

AU - Mitchell, Ralph

N1 - Funding Information: This research was supported in part by a grant from the U.S. Army Corps and Engineers No. DACW39-95-K-0038. Preparation of this manuscript was made possible by The University of Hong Kong CRCG research grant and the Chinese Academy of Sciences. We thank Edward L. Mills of Cornell University Biological Field Station for the supply of mussels used in this study, Edward Seling for SEM observation, Yanzhen Fan for graphics, and Rhonda Penny and Ka Hong Cheung for reading and commenting on the manuscript.

PY - 2002/4/15

Y1 - 2002/4/15

N2 - Freshwater fouling invertebrate zebra mussels (Dreissena polymorpha) harbor a diverse population of microorganisms in the Great Lakes of North America. Among the indigenous microorganisms, selective species are opportunistic pathogens to zebra mussels. Pathogenicity to zebra mussels by opportunistic bacteria isolated from the mussels was investigated in this study. Among the more than 30 bacteria isolated from temperature-stressed mussels, Aeromonas media, A. veronii, A. salmonicida subsp. salmonicida, and Shewanella putrefaciens are virulent pathogens to juvenile zebra mussels. Inoculation of a bacterial concentration of A. media, A. salmonicida subsp. salmonicida and S. putrefaciens at 107 cells per zebra mussel resulted in 100% mortality within 5 days, and only 64.9% for A. veronii. In contrast, mortality was less than 12.3% following inoculation of a sterile phosphate buffer solution as a control. In addition, mortality was dependent on the size of the pathogen population used in inoculation and the incubation temperature, indicating the close relationship between the bacterial population and subsequent death. On the mussel tissue, a dense microbial population was evident from the moribund mussels viewed with Scanning Electron Microscope (SEM). Opportunistic bacteria invaded and destroyed the D. polymorpha tissue after 7 days of incubation when the bacterial inoculation was larger than 105 per zebra mussel. Our results suggest that mussels are reservoirs of opportunistic pathogenic microorganisms to aquatic organisms and humans and a better understanding of the microbial ecology of the mussels will provide insights to the possible health hazards from these microorganisms.

AB - Freshwater fouling invertebrate zebra mussels (Dreissena polymorpha) harbor a diverse population of microorganisms in the Great Lakes of North America. Among the indigenous microorganisms, selective species are opportunistic pathogens to zebra mussels. Pathogenicity to zebra mussels by opportunistic bacteria isolated from the mussels was investigated in this study. Among the more than 30 bacteria isolated from temperature-stressed mussels, Aeromonas media, A. veronii, A. salmonicida subsp. salmonicida, and Shewanella putrefaciens are virulent pathogens to juvenile zebra mussels. Inoculation of a bacterial concentration of A. media, A. salmonicida subsp. salmonicida and S. putrefaciens at 107 cells per zebra mussel resulted in 100% mortality within 5 days, and only 64.9% for A. veronii. In contrast, mortality was less than 12.3% following inoculation of a sterile phosphate buffer solution as a control. In addition, mortality was dependent on the size of the pathogen population used in inoculation and the incubation temperature, indicating the close relationship between the bacterial population and subsequent death. On the mussel tissue, a dense microbial population was evident from the moribund mussels viewed with Scanning Electron Microscope (SEM). Opportunistic bacteria invaded and destroyed the D. polymorpha tissue after 7 days of incubation when the bacterial inoculation was larger than 105 per zebra mussel. Our results suggest that mussels are reservoirs of opportunistic pathogenic microorganisms to aquatic organisms and humans and a better understanding of the microbial ecology of the mussels will provide insights to the possible health hazards from these microorganisms.

KW - Bacteria

KW - Biofouling

KW - Dreissena polymorpha

KW - Microflora

KW - Opportunistic pathogens

KW - Zebra mussel

UR - http://www.scopus.com/inward/record.url?scp=0037092214&partnerID=8YFLogxK

U2 - 10.1023/A:1016517107473

DO - 10.1023/A:1016517107473

M3 - 文章

AN - SCOPUS:0037092214

SN - 0018-8158

VL - 474

SP - 81

EP - 90

JO - Hydrobiologia

JF - Hydrobiologia

ER -