title: Novel bacterial isolate from Permian groundwater, capable of aggregating potential biofuel-producing microalga Nannochloropsis oceanica IMET1.
abstract: Increasing petroleum costs and climate change have resulted in microalgae receiving attention as potential biofuel producers. Little information is available on the diversity and functions of bacterial communities associated with biofuel-producing algae. A potential biofuel-producing microalgal strain, Nannochloropsis oceanica IMET1, was grown in Permian groundwater. Changes in the bacterial community structure at three temperatures were monitored by two culture-independent methods, and culturable bacteria were characterized. After 9 days of incubation, N. oceanica IMET1 began to aggregate and precipitate in cultures grown at 30°C, whereas cells remained uniformly distributed at 15°C and 25°C. The bacterial communities in cultures at 30°C changed markedly. Some bacteria isolated only at 30°C were tested for their potential for aggregating microalgae. A novel bacterium designated HW001 showed a remarkable ability to aggregate N. oceanica IMET1, causing microalgal cells to aggregate after 3 days of incubation, while the total lipid content of the microalgal cells was not affected. Direct interaction of HW001 and N. oceanica is necessary for aggregation. HW001 can also aggregate the microalgae N. oceanica CT-1, Tetraselmis suecica, and T. chuii as well as the cyanobacterium Synechococcus WH8007. 16S rRNA gene sequence comparisons indicated the great novelty of this strain, which exhibited only 89% sequence similarity with any previously cultured bacteria. Specific primers targeted to HW001 revealed that the strain originated from the Permian groundwater. This study of the bacterial communities associated with potential biofuel-producing microalgae addresses a little-investigated area of microalgal biofuel research and provides a novel approach to harvest biofuel-producing microalgae by using the novel bacterium strain HW001.
authors.affiliation: Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, MD, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Haywood D
authors.initials: HD
authors.lastname: Laughinghouse
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Anderson
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Ernest
authors.initials: E
authors.lastname: Willliams
authors.forename: Allen R
authors.initials: AR
authors.lastname: Place
authors.forename: Odi
authors.initials: O
authors.lastname: Zmora
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Zohar
authors.forename: Tianling
authors.initials: T
authors.lastname: Zheng
authors.forename: Russell T
authors.initials: RT
authors.lastname: Hill
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D056804:Biofuels; D002448:Cell Adhesion; D000460:Chlorophyta / Q000502:physiology; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D060587:Groundwater / Q000382:microbiology*; D056265:Microbial Interactions; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D058009:Stramenopiles / Q000378:metabolism / Q000502:physiology*; D013696:Temperature
chemical_list: D056804:Biofuels; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S