The proliferation of Internet-of-Things has promoted a wide variety of emerging applications that require compact, lightweight, and low-cost optical spectrometers. While substantial progresses have been made in the miniaturization of spectrometers, most of them are with a major focus on the technical side but tend to feature a lower technology readiness level for manufacturability. More importantly, in spite of the advancement in miniaturized spectrometers, their performance and the metrics of real-life applications have seldomly been connected but are highly important. This review paper shows the market trend for chip-scale spectrometers and analyzes the key metrics that are required to adopt miniaturized spectrometers in real-life applications. Recent progress addressing the challenges of miniaturization of spectrometers is summarized, paying a special attention to the CMOS-compatible fabrication platform that shows a clear pathway to massive production. Insights for ways forward are also presented.
Microalgal starch is a potential feedstock for biofuel production. Nutrient stress is widely used to stimulate starch accumulation in microalgae. Cell growth and starch accumulation in the marine green microalga Tetraselmis subcordiformis were evaluated under extracellular phosphorus deprivation with initial cell densities (ICD) of 1.5, 3.0, 6.0, and 9.0×10 6 cells mL were all obtained in the culture with the ICD of 3.0× 10 6 cells mL −1 . Appropriate ICD could be used to regulate the intracellular phosphorus concentration and maintain adequate photosynthetic activity to achieve the highest starch productivity, along with biomass and starch concentration. The recovery of phosphorus-deprived T. subcordiformis in medium containing 0.5, 1.0, or 6.0 mM KH 2 PO 4 was also tested. Cell growth and starch accumulation ability could be recovered completely. A phosphorus pool in T. subcordiformis was shown to manipulate its metabolic activity under different environmental phosphorus availability. Though lower starch productivity and starch content were achieved under phosphorus deprivation compared with nitrogen-or sulfur-deprived conditions, the higher biomass and starch concentration make T. subcordiformis a good candidate for biomass and starch production under extracellular phosphorus deprivation.
Background
Carbohydrates are major biomass source in fuel-targeted biorefinery.
Arthrospira platensis
is the largest commercialized microalgae with good environmental tolerance and high biomass production. However, the traditional target of
A. platensis
cultivation is the protein, which is the downstream product of carbohydrates. Aiming to provide the alternative non-food carbohydrates source, the feasible manipulation technology on the cultivation is needed, as well as new separation methodology to achieve maximum utilization of overall biomass.
Results
The present study aimed to demonstrate the feasibility of industrially producing carbohydrate-enriched
A. platensis
and characterize the structure of the polysaccharide involved. Cultivated in industrial-scale outdoor open raceway ponds under nitrogen limitation,
A. platensis
accumulated maximally 64.3%DW of carbohydrate. The maximum biomass and carbohydrate productivity reached 27.5 g m
−2
day
−1
and 26.2 g m
−2
day
−1
, respectively. The efficient extraction and purification of the polysaccharides include a high-pressure homogenization-assisted hot water extraction followed by flocculation with a non-toxic flocculant ZTC1 + 1, with the polysaccharide purity and total recovery reaching 81% and 75%, respectively. The purified polysaccharide was mainly composed of (1→3)(1→4)- or (1→3)(1→2)-α-glucan with a molecular weight of 300–700 kDa, which differed from the commonly acknowledged glycogen.
Conclusions
By the way of controlled nitrogen limitation, the high carbohydrate production of
A. platensis
in the industrial scale was achieved. The α-glucan from
A. platensis
could be a potential glucose source for industrial applications. A non-toxic separation method of carbohydrate was applied to maintain the possibility of utilization of residue in high-value field.
Electronic supplementary material
The online version of this article (10.1186/s13068-019-1470-3) contains supplementary material, which is available to authorized users.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.