Dictyosphaerium chlorelloides is a green microalga from the Chlorella clade that produces highly viscous exocellular polysaccharides. The cell wall polysaccharides of this alga have not been studied in detail. In this article, water-soluble polysaccharides from D. chlorelloides biomass were extracted with hot water and purified by preparative chromatography. The composition, structural features and molecular masses of subsequently eluted fractions F1, F2, F3, F4 and F5 (minor) were determined. Three high-yield products F1, F3 and F4 consisted mainly of galactopyranosyl, 2-O-methyl-galactopyranosyl, rhamnopyranosyl and mannopyranosyl units at different proportions, while F2 was rich in glucose. Immunoactivity of these fractions was evidenced in a mixed population of immune cells derived from mice spleens after incubation with polysaccharides by flow cytometry, MTT and Immunospot assays. These fractions, except F2, demonstrated selective immunostimulant activity, and the F1 fraction induced the most potent effect, closely followed by the F3 and F4 fractions. The in vivo mechanism of their action is associated with the activation of innate immunity and shapes the immune response to the Th1 type.
- MeSH
- Adjuvants, Immunologic pharmacology chemistry isolation & purification MeSH
- Cell Wall * chemistry MeSH
- Chlorophyta chemistry MeSH
- Microalgae * chemistry MeSH
- Mice, Inbred BALB C MeSH
- Mice MeSH
- Polysaccharides * pharmacology chemistry isolation & purification MeSH
- Spleen cytology drug effects MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
This review summarizes the available information about potential sources of vitamin B12, especially for people who follow a vegan or vegetarian diet and inhabitants of poor countries in the developing world. Cyanobacteria and microalgae approved for food purposes can play a critical role as promising and innovative sources of this vitamin. This work involves a discussion of whether the form of vitamin B12 extracted from microalgae/cyanobacteria is biologically available to humans, specifically focusing on the genera Arthrospira and Chlorella. It describes analyses of their biomass composition, cultivation requirements, and genetic properties in B12 production. Furthermore, this review discusses the function of cobalamin in microalgae and cyanobacteria themselves and the possibility of modification and cocultivation to increase the content of B12 in their biomass.
- MeSH
- Biomass MeSH
- Chlorella * MeSH
- Humans MeSH
- Microalgae * MeSH
- Cyanobacteria * MeSH
- Vitamin B 12 analysis MeSH
- Vitamins MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
The unicellular green microalga Dunaliella is a potential source of a wide range of nutritionally important compounds applicable to the food industry. The aim of this study was to assess the effect of Dunaliella salina dried biomass on the growth and adherence of 10 strains of Lactobacillus, Lacticaseibacillus, and Bifidobacterium. The immunomodulatory, antioxidant, and cytotoxic effects of D. salina on human peripheral mononuclear cells and simulated intestinal epithelial cell lines Caco-2 and HT-29 were evaluated. Furthermore, the hypocholesterolemic effects of the microalgae on lipid metabolism in rats fed a high-fat diet were analyzed. The addition of D. salina biomass had a positive effect on the growth of nine out of 10 probiotics and promoted the adherence of three bifidobacteria strains to human cell lines. The antioxidant and immunomodulatory properties of D. salina were concentration-dependent. The inflammatory cytokines (TNF-α and IL-6) were significantly increased following Dunaliella stimulation at the lowest concentration (0.5% w/v). Eight week supplementation of D. salina to the diet of hypercholesteromic rats significantly decreased the serum concentrations of LDL-C, VLDL, IDL-B, and IDL-C. D. salina is not cytotoxic in intestinal cell models; it promotes adherence of selected bifidobacteria, it affords immunomodulatory and antioxidant effects, and its addition to diets may help decrease atherosclerosis risk factors.
- MeSH
- Antioxidants pharmacology metabolism MeSH
- Biomass MeSH
- Caco-2 Cells MeSH
- Chlorophyceae * MeSH
- Rats MeSH
- Humans MeSH
- Microalgae * metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
This work represents a detailed guide for commitment point analysis in microalgae dividing by multiple fission. The method is based on allowing the committed cells to divide in favorable conditions in the dark. This protocol offers a strategy to monitor cell cycle progression, both in control cultures and cultures treated with compounds affecting cell cycle length and/or progression. As the variety of such compounds is wide, our aim was to make the protocol easily modifiable to various research aims. The technique is easy to follow, low-cost, does not require any special equipment and offers reliable results in a reasonable time. The protocol offers step-by-step instructions, explains the theory behind these steps and offers solutions to some of the problems that may arise during the procedure.
- MeSH
- Cell Division * MeSH
- Cell Cycle * MeSH
- Viridiplantae MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Green algae are fast-growing microorganisms that are considered promising for the production of starch and neutral lipids, and the chlorococcal green alga Parachlorella kessleri is a favorable model, as it can produce both starch and neutral lipids. P. kessleri commonly divides into more than two daughter cells by a specific mechanism-multiple fission. Here, we used synchronized cultures of the alga to study the effects of supra-optimal temperature. Synchronized cultures were grown at optimal (30 °C) and supra-optimal (40 °C) temperatures and incident light intensities of 110 and 500 μmol photons m-2 s-1. The time course of cell reproduction (DNA replication, cellular division), growth (total RNA, protein, cell dry matter, cell size), and synthesis of energy reserves (net starch, neutral lipid) was studied. At 40 °C, cell reproduction was arrested, but growth and accumulation of energy reserves continued; this led to the production of giant cells enriched in protein, starch, and neutral lipids. Furthermore, we examined whether the increased temperature could alleviate the effects of deuterated water on Parachlorella kessleri growth and division; results show that supra-optimal temperature can be used in algal biotechnology for the production of protein, (deuterated) starch, and neutral lipids.
An increase in temperature can have a profound effect on the cell cycle and cell division in green algae, whereas growth and the synthesis of energy storage compounds are less influenced. In Chlamydomonas reinhardtii, laboratory experiments have shown that exposure to a supraoptimal temperature (39 °C) causes a complete block of nuclear and cellular division accompanied by an increased accumulation of starch. In this work we explore the potential of supraoptimal temperature as a method to promote starch production in C. reinhardtii in a pilot-scale photobioreactor. The method was successfully applied and resulted in an almost 3-fold increase in the starch content of C. reinhardtii dry matter. Moreover, a maximum starch content at the supraoptimal temperature was reached within 1-2 days, compared with 5 days for the control culture at the optimal temperature (30 °C). Therefore, supraoptimal temperature treatment promotes rapid starch accumulation and suggests a viable alternative to other starch-inducing methods, such as nutrient depletion. Nevertheless, technical challenges, such as bioreactor design and light availability within the culture, still need to be dealt with.
- MeSH
- Biomass * MeSH
- Bioreactors MeSH
- Cell Cycle MeSH
- Chlamydomonas reinhardtii metabolism MeSH
- Photobioreactors * MeSH
- Culture Media MeSH
- Microalgae MeSH
- Industrial Microbiology methods MeSH
- Starch metabolism MeSH
- Light MeSH
- Temperature MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Toxicity of lanthanides is generally regarded as low, and they even have been suggested to be beneficial at low concentrations. This research was conducted to investigate effects of Lanthanum (La) on Desmodesmus quadricauda, a freshwater green microalga. The algal cultures were treated with nanomolar La concentrations under controlled environmentally relevant conditions. Intracellular localization of La was analyzed with μXRF tomography in frozen-hydrated samples. At sublethal concentration (128 nM) La was in hotspots inside the cells, while at lethal 1387 nM that led to release of other ions (K, Zn) from the cells, La filled most of the cells. La had no clear positive effects on growth or photosynthetic parameters, but increasing concentrations led to a dramatic decrease in cell counts. Chlorophyll fluorescence kinetic measurements showed that La led to the inhibition of photosynthesis. Maximal photochemical quantum yield of the PSII reaction center in dark-adapted state (Fv/Fm) decreased at > 4.3 nM La during the 2nd week of treatment. Minimum dark-adapted fluorescence quantum yield (F0) increased at > 13.5 nM La during the 2nd week of treatment except for control (0.2 nM La, baseline from chemicals) and 0.3 nM La. NPQ at the beginning of the actinic light phase showed significant increase for all the treatments. Metalloproteomics by HPLC-ICPMS showed that La binds to a >500 kDa soluble protein complex already in the sub-nM range of La treatments, in the low nM range to a small-sized (3 kDa) soluble peptide, and at >100 nM La additionally binds to a 1.5 kDa ligand.
- MeSH
- Water Pollutants, Chemical toxicity MeSH
- Chlorophyll metabolism MeSH
- Chlorophyta drug effects physiology MeSH
- Fluorescence MeSH
- Photosynthesis drug effects MeSH
- Photosystem II Protein Complex drug effects metabolism MeSH
- Lanthanum metabolism toxicity MeSH
- Plant Leaves metabolism MeSH
- Publication type
- Journal Article MeSH
OBJECTIVE: Desalination of cheese whey by electrodialysis yields saline wastewater (SWW). The goal was to test this as the basis of a culture medium and to prove experimentally the concept that it was a suitable resource for heterotrophic cultivation of the freshwater green microalga Chlorella vulgaris. RESULTS: Optimization of glucose concentration, nitrogen source and medium salinity for microalgal growth was first carried out in defined medium (DM) and shake flasks. These results were then adopted in shake flask cultivation experiments using pre-treated SWW medium (PSWW). Subsequently, microalgal growth under optimized conditions was tested in bioreactors. Various media such as DM, PSWW and diluted PSWW (DPSWW) were compared. Volumetric biomass productivities decreased in the order DM (0.371 g L-1 h-1, urea) > DPSWW (0.315 g L-1 h-1, soy peptone) > PSWW (0.152 g L-1 h-1, soy peptone). Although biomass productivities in DPSWW and PSWW media were significantly lower than in DM, these media required the addition of only 66 and 33% of DM N sources, respectively. No other added DM component was necessary in (D)PSWW to achieve microalgal growth. CONCLUSIONS: Although the optimized cultivation of freshwater microalgae on alternative medium based on SWW resulted in biomass productivities lower than those on DM, the required addition of N sources was also lower. Potentially lower production costs of Chlorella biomass and the meaningful use of SWW are the main outcomes of this work.
The green algal genus Cylindrocystis is widespread in various types of environments, including extreme habitats. However, very little is known about its diversity, especially in polar regions. In the present study, we isolated seven new Cylindrocystis-like strains from terrestrial and freshwater habitats in Svalbard (High Arctic). We aimed to compare the new isolates on a molecular (rbcL and 18S rDNA), morphological (light and confocal laser scanning microscopy), and cytological (Raman microscopy) basis. Our results demonstrated that the Arctic Cylindrocystis were not of a monophyletic origin and that the studied strains clustered within two clades (tentatively named the soil and freshwater/glacier clades) and four separate lineages. Morphological data (cell size, shape, and chloroplast morphology) supported the presence of several distinct taxa among the new isolates. Moreover, the results showed that the Arctic Cylindrocystis strains were closely related to strains originating from the temperate zone, indicating high ecological versatility and successful long-distance dispersal of the genus. Large amounts of inorganic polyphosphate (polyP) grains were detected within the chloroplasts of the cultured Arctic Cylindrocystis strains, suggesting effective luxury uptake of phosphorus. Additionally, various intracellular structures were identified using Raman microscopy and cytochemical and fluorescent staining. This study represents the first attempt to combine molecular, morphological, ecological, and biogeographical data for Arctic Cylindrocystis. Our novel cytological observations partially explain the success of Cylindrocystis-like microalgae in polar regions.
- MeSH
- Chlorophyta * MeSH
- Phylogeny MeSH
- Polyphosphates MeSH
- Streptophyta * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Arctic Regions MeSH
- Svalbard MeSH
