The survivor strain: isolation and characterization of Phormidium yuhuli AB48, a filamentous phototactic cyanobacterium with biotechnological potential

Abstract

Despite their recognized potential, current applications of cyanobacteria as microbial cell factories remain in early stages of development. This is partly due to the fact that engineered strains are often difficult to grow at scale. This technical challenge contrasts with the dense and highly productive cyanobacteria populations thriving in many natural environments. It has been proposed that the selection of strains pre-adapted for growth in industrial photobioreactors could enable more productive cultivation outcomes. Here, we described the initial morphological, physiological, and genomic characterization of Phormidium yuhuli AB48 isolated from an industrial photobioreactor environment. P. yuhuli AB48 is a filamentous phototactic cyanobacterium with a growth rate comparable to Synechocystis sp. PCC 6803. The isolate forms dense biofilms under high salinity and alkaline conditions and manifests a similar nutrient profile to Arthrospira platensis (Spirulina). We sequenced, assembled, and analyzed the P. yuhuli AB48 genome, the first closed circular isolate reference genome for a member of the Phormidium genus. We then used cultivation experiments in combination with proteomics and metabolomics to investigate growth characteristics and phenotypes related to industrial scale cultivation, including nitrogen and carbon utilization, salinity, and pH acclimation, as well as antibiotic resistance. These analyses provide insight into the biological mechanisms behind the desirable growth properties manifested by P. yuhuli AB48 and position it as a promising microbial cell factory for industrial-scale bioproduction[221, 1631].

Using FlowCam and molecular techniques to assess the diversity of Cyanobacteria species in water used for food production

“…Individual cells of Phormidium sp. are between 2.8 and 3.5 µm wide and 5 to 8 µm in length, while filaments extend up to 400 µm 53 . Another genus that was recognized based on morphological characteristics was Leptolyngbya sp.…”

“…According to Palinska et al 52 , Phormidium sp. is characterized based on morphological features such as thin, hyaline, partly diffluent, or completely dissolved sheaths, which cause filaments to stick together in mat–like layers or structures that may contribute to biofilm formation 53 . This unbranched filamentous species does not produce any specialized cells, such as heterocysts.…”

Complete Genome Sequence of Phormidium yuhuli AB48, Isolated from an Industrial Photobioreactor Environment

“…Here, we report the complete genome sequence of Phormidium yuhuli AB48, which was first described by Koch and colleagues ( 4 ). P. yuhuli AB48 was isolated from an industrial photobioreactor environment operated under elevated temperature (35°C to 45°C), salinity (10 g/L), and alkalinity (pH 9 to pH 11).…”

“… P. yuhuli AB48 was isolated from an industrial photobioreactor environment operated under elevated temperature (35°C to 45°C), salinity (10 g/L), and alkalinity (pH 9 to pH 11). Grown as a biofilm under these conditions, AB48 was found to co-occur with several other microorganisms ( 5 ) prior to isolation using a gradient culture method ( 4 ). To prepare genomic DNA for sequencing, the isolate was cultured under continuous light in 50 mL of Zarrouk medium ( 6 ) in an Erlenmeyer flask for 96 h prior to biomass collection.…”

Metagenome-Assembled Genomes for “ Candidatus Phormidium sp. Strain AB48” and Co-occurring Microorganisms from an Industrial Photobioreactor Environment

“…SRR13132258 . This BioProject also includes BioSample SAMN28044976 ; this represents a distinct sample and contains Oxford Nanopore Technologies and Illumina data sets for Phormidium yuhuli AB48, which was isolated from the photobioreactor enrichment described here ( 23 ).…”