Effect of Temperature and Salt on Laboratory Growth of Vampirovibrio chlorellavorus and Killing of a Cultivated Chlorella Host

Persistent Link:
http://hdl.handle.net/10150/596089
Title:
Effect of Temperature and Salt on Laboratory Growth of Vampirovibrio chlorellavorus and Killing of a Cultivated Chlorella Host
Author:
Li, Xuehui
Issue Date:
2015
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release 08-Dec-2016
Abstract:
Vampirovibrio chlorellavorus (Gromov et Mamkaeva, 1980) is a member of the phylum cyanobacteria that has been described as an obligate pathogen of several of the green microalga, Chlorella. It utilizes as yet unknown functions to access the contents of individual Chlorella sp. host cells, which results in cell death. Its presence in a cultivated Chlorella sorokiniana culture was first discovered using polymerase chain reaction (PCR) to amplify the 16S ribosomal DNA gene, followed by DNA sequencing. Its continued routine detection throughout much of the cultivation season suggested it was an endemic member of the phycosphere community in this open cultivation system, located in Tucson, Arizona. Ultimately, its presence resulted in rapid death of C. sorokiniana in open pond systems and reduced biomass harvest. PCR analysis of total DNA isolated from sand and soil layers removed from a nearby riverbed indicated that V. chlorellavorus resides naturally in the riverbed. The ability to manage this bacterial pathogen in cultivated Chlorella host species is hindered by the limited information available in the literature regarding the biological and genomic characteristics of V. chlorellavorus. The objective of this study was to identify environmental factors that trigger the apparent increased growth rate of V. chlorellavorus and rapid algal death during the cultivation cycle. In laboratory experiments, V. chlorellavorus was shown to cause death of C. sorokiniana when the temperature exceeded 28°C, whereas, algal death was not observed when the temperature was 24°C or lower, among the temperatures tested. Also, the bacterium was more pathogenic to C. sorokiniana, grown in open cultivation systems during the summer months, compared to the cooler season months. Futhermore, when C. sorokiniana and V. chlorellavorus were co-cultivated in the presence of sodium chloride ranging from 0-10 g per liter, the growth of the bacterium was not impeded to any extent that might suggest C. sorokiniana was rendered less susceptibility to pathogen attack. Future work involves examining more triggers and ways to inhibit V. chlorellavorus growth.
Type:
text; Electronic Thesis
Keywords:
microalgae; outdoor algal cultivation; salinity; SEM; Chemical Engineering; DOE1412
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Chemical Engineering
Degree Grantor:
University of Arizona
Advisor:
Ogden, Kimberly L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleEffect of Temperature and Salt on Laboratory Growth of Vampirovibrio chlorellavorus and Killing of a Cultivated Chlorella Hosten_US
dc.creatorLi, Xuehuien
dc.contributor.authorLi, Xuehuien
dc.date.issued2015en
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.releaseRelease 08-Dec-2016en
dc.description.abstractVampirovibrio chlorellavorus (Gromov et Mamkaeva, 1980) is a member of the phylum cyanobacteria that has been described as an obligate pathogen of several of the green microalga, Chlorella. It utilizes as yet unknown functions to access the contents of individual Chlorella sp. host cells, which results in cell death. Its presence in a cultivated Chlorella sorokiniana culture was first discovered using polymerase chain reaction (PCR) to amplify the 16S ribosomal DNA gene, followed by DNA sequencing. Its continued routine detection throughout much of the cultivation season suggested it was an endemic member of the phycosphere community in this open cultivation system, located in Tucson, Arizona. Ultimately, its presence resulted in rapid death of C. sorokiniana in open pond systems and reduced biomass harvest. PCR analysis of total DNA isolated from sand and soil layers removed from a nearby riverbed indicated that V. chlorellavorus resides naturally in the riverbed. The ability to manage this bacterial pathogen in cultivated Chlorella host species is hindered by the limited information available in the literature regarding the biological and genomic characteristics of V. chlorellavorus. The objective of this study was to identify environmental factors that trigger the apparent increased growth rate of V. chlorellavorus and rapid algal death during the cultivation cycle. In laboratory experiments, V. chlorellavorus was shown to cause death of C. sorokiniana when the temperature exceeded 28°C, whereas, algal death was not observed when the temperature was 24°C or lower, among the temperatures tested. Also, the bacterium was more pathogenic to C. sorokiniana, grown in open cultivation systems during the summer months, compared to the cooler season months. Futhermore, when C. sorokiniana and V. chlorellavorus were co-cultivated in the presence of sodium chloride ranging from 0-10 g per liter, the growth of the bacterium was not impeded to any extent that might suggest C. sorokiniana was rendered less susceptibility to pathogen attack. Future work involves examining more triggers and ways to inhibit V. chlorellavorus growth.en
dc.typetexten
dc.typeElectronic Thesisen
dc.subjectmicroalgaeen
dc.subjectoutdoor algal cultivationen
dc.subjectsalinityen
dc.subjectSEMen
dc.subjectChemical Engineeringen
dc.subjectDOE1412en
thesis.degree.nameM.S.en
thesis.degree.levelmastersen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineChemical Engineeringen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorOgden, Kimberly L.en
dc.contributor.committeememberOgden, Kimberly L.en
dc.contributor.committeememberGuzman, Roberto Z.en
dc.contributor.committeememberSaez, Avelino E.en
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