Presentation Information
[P02-238]Predator-driven screening identifies multiple novel morphogenesis factors in cyanobacteria
○Yoshihiro Manago1, Narumi Toda1, Akio Kuroda1, Ryuichi Hirota1 (1. Graduate School of Integrated Sciences for Life, Hiroshima University (Japan))
Keywords:
Cyanobacteria,Synechococcus,Predation,Transporter,Cell morphogenesis
[Background and Objectives]
Cyanobacteria are promising hosts for sustainable bioprocessing because they convert CO2 into biomass through photosynthesis and are increasingly explored as platforms for producing alcohols, chemicals, and other valuable compounds. However, large-scale outdoor cultivation often suffers from productivity loss due to contamination by predatory microorganisms. In our previous study, prolonged co-cultivation of unicellular cyanobacteria with predatory protists resulted in the emergence of mutant cyanobacterial strains exhibiting altered cell morphologies, including elongated cell forms. Such predator-driven morphological alterations have been observed across multiple cyanobacteria-predator combinations, suggesting that morphological change represents a conserved adaptive strategy that enhances cyanobacterial survival under grazing pressure. These morphological traits remain stable after isolation, indicating that they arise from heritable genetic mutations rather than transient physiological responses. Genome resequencing of the isolated mutants identified mutations in genes involved in cell division and peptidoglycan remodeling, as well as in genes not previously reported with cell morphology. The objective of this study was to analyze genes responsible for predator-induced morphological changes in cyanobacteria and to characterize previously unrecognized factors underlying cyanobacterial cell morphogenesis.
[Methods and Results]
Long-term co-cultivation with predatory protists resulted in the isolation of 20 morphological mutant strains from PCC 7002. Compared with the wild-type strain, these mutants exhibited marked cell elongation, ranging from several-fold to over hundred-fold increases in cell length. Whole-genome resequencing revealed mutations in known genes associated with cell morphogenesis in many of the mutant strains. However, in one strain, a mutation was identified solely in the gene SYNPCC7002_A0310, which has not previously been reported with cell morphology. The encoded protein shares approximately 41% amino acid sequence identity with BioY, the biotin transporter of Corynebacterium glutamicum, and is predicted to contain multiple transmembrane helices, suggesting that it is a membrane protein potentially involved in biotin transport. Furthermore, to assess the generality of this approach, we performed a similar predator-driven screening in the marine cyanobacterium Synechococcus sp. NIES 3083 and identified a mutation in a gene encoding a GumC-like polysaccharide export protein, which has no known role in cell morphogenesis. These results demonstrate that predator-driven screening is an effective strategy for uncovering previously unrecognized determinants of cyanobacterial cell morphogenesis, highlighting ecological selection as a powerful approach to reveal latent morphogenetic functions beyond canonical cell division pathways.
Cyanobacteria are promising hosts for sustainable bioprocessing because they convert CO2 into biomass through photosynthesis and are increasingly explored as platforms for producing alcohols, chemicals, and other valuable compounds. However, large-scale outdoor cultivation often suffers from productivity loss due to contamination by predatory microorganisms. In our previous study, prolonged co-cultivation of unicellular cyanobacteria with predatory protists resulted in the emergence of mutant cyanobacterial strains exhibiting altered cell morphologies, including elongated cell forms. Such predator-driven morphological alterations have been observed across multiple cyanobacteria-predator combinations, suggesting that morphological change represents a conserved adaptive strategy that enhances cyanobacterial survival under grazing pressure. These morphological traits remain stable after isolation, indicating that they arise from heritable genetic mutations rather than transient physiological responses. Genome resequencing of the isolated mutants identified mutations in genes involved in cell division and peptidoglycan remodeling, as well as in genes not previously reported with cell morphology. The objective of this study was to analyze genes responsible for predator-induced morphological changes in cyanobacteria and to characterize previously unrecognized factors underlying cyanobacterial cell morphogenesis.
[Methods and Results]
Long-term co-cultivation with predatory protists resulted in the isolation of 20 morphological mutant strains from PCC 7002. Compared with the wild-type strain, these mutants exhibited marked cell elongation, ranging from several-fold to over hundred-fold increases in cell length. Whole-genome resequencing revealed mutations in known genes associated with cell morphogenesis in many of the mutant strains. However, in one strain, a mutation was identified solely in the gene SYNPCC7002_A0310, which has not previously been reported with cell morphology. The encoded protein shares approximately 41% amino acid sequence identity with BioY, the biotin transporter of Corynebacterium glutamicum, and is predicted to contain multiple transmembrane helices, suggesting that it is a membrane protein potentially involved in biotin transport. Furthermore, to assess the generality of this approach, we performed a similar predator-driven screening in the marine cyanobacterium Synechococcus sp. NIES 3083 and identified a mutation in a gene encoding a GumC-like polysaccharide export protein, which has no known role in cell morphogenesis. These results demonstrate that predator-driven screening is an effective strategy for uncovering previously unrecognized determinants of cyanobacterial cell morphogenesis, highlighting ecological selection as a powerful approach to reveal latent morphogenetic functions beyond canonical cell division pathways.
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