A comparison of methods for the non-destructive fresh weight determination of filamentous algae for growth rate analysis and dry weight estimation

The determination of rates of macroalgal growth and productivity via temporal fresh weight (FW) measurements is attractive, as it does not necessitate the sacrifice of biomass. However, there is no standardised method for FW analysis; this may lead to potential discrepancies when determining growth rates or productivity and make literature comparison problematic. This study systematically assessed a variety of lab-scale methods for macroalgal FW measurement for growth rate determination. Method efficacy was assessed over a 14-day period as impact upon algal physiology, growth rate on basis of FW and dry weight (DW), nitrate removal, and maintenance of structural integrity. The choice of method is critical to both accuracy and inter-study comparability of the data generated. In this study, it was observed that the choice of protocol had an impact upon the DW yield (P values = 0.036–0.51). For instance, those involving regular mechanical pressing resulted in a >25% reduction in the final DW in two of the three species studied when compared to algae not subjected to any treatment. This study proposes a standardised FW determination method employing a reticulated spinner that is rapid, reliable, and non-destructive and provides an accurate growth estimation

Diploid genomic architecture of Nitzschia inconspicua, an elite biomass production diatom

AbstractA near-complete diploid nuclear genome and accompanying circular mitochondrial and chloroplast genomes have been assembled from the elite commercial diatom species Nitzschia inconspicua. The 50 Mbp haploid size of the nuclear genome is nearly double that of model diatom Phaeodactylum tricornutum, but 30% smaller than closer relative Fragilariopsis cylindrus. Diploid assembly, which was facilitated by low levels of allelic heterozygosity (2.7%), included 14 candidate chromosome pairs composed of long, syntenic contigs, covering 93% of the total assembly. Telomeric ends were capped with an unusual 12-mer, G-rich, degenerate repeat sequence. Predicted proteins were highly enriched in strain-specific marker domains associated with cell-surface adhesion, biofilm formation, and raphe system gliding motility. Expanded species-specific families of carbonic anhydrases suggest potential enhancement of carbon concentration efficiency, and duplicated glycolysis and fatty acid synthesis pathways across cytosolic and organellar compartments may enhance peak metabolic output, contributing to competitive success over other organisms in mixed cultures. The N. inconspicua genome delivers a robust new reference for future functional and transcriptomic studies to illuminate the physiology of benthic pennate diatoms and harness their unique adaptations to support commercial algae biomass and bioproduct production.</jats:p

Diploid Genomic Architecture of Nitzschia Hildebrandi, An Elite Biomass Production Diatom

Abstract A near-complete diploid nuclear genome and accompanying circular mitochondrial and chloroplast genomes have been assembled from the elite commercial diatom species Nitzschia hildebrandi. The 50 Mbp haploid size of the nuclear genome is nearly double that of model diatom Phaeodactylum tricornutum, but 30% smaller than closer relative Fragilariopsis cylindrus. Diploid assembly, which was facilitated by low levels of allelic heterozygosity (2.7%), included 14 candidate chromosome pairs composed of long, syntenic contigs, covering 93% of the total assembly. Telomeric ends were capped with an unusual 12-mer, G-rich, degenerate repeat sequence. Predicted proteins were highly enriched in strain-specific marker domains associated with cell-surface adhesion, biofilm formation, and raphe system gliding motility. Expanded species-specific families of carbonic anhydrases suggest potential enhancement of carbon concentration efficiency, and duplicated glycolysis and fatty acid synthesis pathways across cytosolic and organellar compartments may enhance peak metabolic output, contributing to competitive success over other organisms in mixed cultures. The N. hildebrandi genome delivers a robust new reference for future functional and transcriptomic studies to illuminate the physiology of benthic pennate diatoms and harness their unique adaptations to support commercial algae biomass and bioproduct production.</jats:p