AUTHOR=Chen Zhangran , Zheng Wei , Yang Luxi , Boughner Lisa A. , Tian Yun , Zheng Tianling , Xu Hong 

TITLE=Lytic and Chemotactic Features of the Plaque-Forming Bacterium KD531 on Phaeodactylum tricornutum

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.02581

DOI=10.3389/fmicb.2017.02581

ISSN=1664-302X

ABSTRACT=<p><italic>Phaeodactylum tricornutum</italic> is a dominant bloom forming species and potential biofuel feedstock. To control <italic>P. tricornutum</italic> bloom or to release lipids from <italic>P. tricornutum</italic>, we previously screened and identified the lytic bacterium <italic>Labrenzia</italic> sp. KD531 toward <italic>P. tricornutum</italic>. In the present study, we evaluated the lytic activity of <italic>Labrenzia</italic> sp. KD531 on microalgae and investigated its lytic mechanism. The results indicated that the lytic activity of KD531 was temperature- and pH-dependent, but light-independent. In addition to <italic>P. tricornutum</italic>, KD531 also showed lytic activity against other algal species, especially green algae. A quantitative analysis of algal cellular protein, carbohydrate and lipid content together with measurements of dry weight after exposure to bacteria-infected algal lysate indicated that the bacterium KD531 influenced the algal biomass by disrupting the algal cells. Both chemotactic analysis and microscopic observations of subsamples from different regions of formed plaques showed that KD531 could move toward and then directly contact algal cells. Direct contact between <italic>P. tricornutum</italic> and KD531 cells was essential for the lytic process.</p>