A novel two-phase bioprocess for the production of Arthrospira (Spirulina) maxima LJGR1 at pilot plant scale during different seasons and for phycocyanin induction under controlled conditions.

A two-phase outdoor cultivation bioprocess for Arthrospira maxima LJGR1 combined with phycocyanin induction in concentrated cultures under controlled conditions was evaluated using a modified low-cost Zarrouk medium. Growth was monitored during 4 cycles in 2018 and 4 cycles in 2019. Biomass was harvested and concentrated using membrane technology at the end of each cycle for further phycocyanin induction using blue LED light (controlled conditions, 24 h). The highest biomass productivity was observed during spring and summer cycles (13.63-18.97 gDWm-2 d-1); during mid-fall and mid-end fall, a decrease was observed (9.93-7.76 gDWm-2 d-1). Under favorable growth conditions, phycocyanin induction was successful. However, during cycles with unfavorable growth condition, phycocyanin induction was not observed. Reactive-grade phycocyanin (3.72 ± 0.14) was recovered and purified using microfiltration and ultrafiltration technologies.

Chlorophyll f and chlorophyll d are produced in the cyanobacterium Chlorogloeopsis fritschii when cultured under natural light and near-infrared radiation.

We report production of chlorophyll f and chlorophyll d in the cyanobacterium Chlorogloeopsis fritschii cultured under near-infrared and natural light conditions. C. fritschii produced chlorophyll f and chlorophyll d when cultured under natural light to a high culture density in a 20 L bubble column photobioreactor. In the laboratory, the ratio of chlorophyll f to chlorophyll a changed from 1:15 under near-infrared, to an undetectable level of chlorophyll f under artificial white light. The results provide support that chlorophylls f and d are both red-light inducible chlorophylls in C. fritschii.

Combining HPLC pigment markers and ecological similarity indices to assess phytoplankton community structure: an environmental tool for eutrophication?

A new tool combining the use of HPLC pigment markers with ecological similarity indices, to provide a fast and effective environmental tool for monitoring water quality, was investigated. HPLC pigment concentrations from a 4-year time series data set (2000-2003) from the western English Channel were used to calculate six similarity indices to assess changes in phytoplankton community structure. Indices obtained from HPLC data were compared with those produced from the corresponding phytoplankton biomass derived from microscopic analysis. Multivariate RELATE analyses (P<0.001) suggested that there was little loss of information when species biomass data were grouped into higher taxonomic levels, thereby providing justification for the use of pigment markers. To test the proposed methodology, product moment (r) and Spearman's rank (r(s)) correlation analyses were performed. Highly significant correlations (P<0.01, Canberra Metric: P<0.05) between percentage similarities derived from phytoplankton class biomass and pigment markers were found for all indices when data were pooled (n=104). A Mann-Whitney U-test suggested that indices were more sensitive to changes in relative biomass than pigment concentrations; however, pigment data also produced statistically significant findings (P<0.05). Combining HPLC pigment markers and ecological similarity indices to assess phytoplankton community structure has advantages over microscopy in that it is rapid, reproducible and better suited to large-scale environmental monitoring. We present a basic protocol for implementing this new tool using a suite of similarity indices into environmental monitoring of phytoplankton communities.

Flow cytometry and pigment analyses as tools to investigate the toxicity of herbicides to natural phytoplankton communities.

Characterisation of natural phytoplanktonic communities is currently being advanced through flow cytometry and high resolution pigment analyses. To date, toxicological methods to assess impacts of herbicides on natural phytoplankton populations are lacking. Here, we report the novel use of these techniques in combination to study changes in phytoplankton populations exposed to 2-methylthio-4-tertiary-butylamino-6-cyclopropylamino-s-triazine (Irgarol 1051), a herbicide used in antifouling paints. Flow cytometry results revealed that following a 72-h exposure to approximately 100 ngL(-1), eukaryote abundance was less than half that in the controls. High performance liquid chromatographic analyses of pigments demonstrated that 19'-hexanoyloxyfucoxanthin was selectively lost relative to the control. This carotenoid is specific to the prymnesiophytes which are key constituents of phytoplanktonic communities within temperate marine waters. Values of EC(50) (72 h) as low as 70 ngL(-1) were calculated from the selective reduction in this compound. Concentrations substantially exceeding this level have been reported in UK and other European coastal waters.

Acute impaction of the rumen in a herd of Friesian cows.

An outbreak of acute impaction of the rumen in a herd of Friesian cows associated with the over eating of young grass and exposure to severe weather conditions, is described. The morbidity rate was 100 per cent and the mortality rate 6-5 per cent.