Edaphic Algae Research Articles

The perspective of the use of algae as a biofertilizer in the cultivation of aromatic and medicinal plants

Algae present a natural source of biofertilizers, efficient, safe and relatively cheap, which can be used in the cultivation of aromatic and medicinal plants. The application of biofertilizers and algal foliar fertilizers to the cultivation of aromatic and medicinal plants contributes to the improvement of the quality of soils, as appropriate their phytoremediation, the improvement of the physiological state of the fields, the increase of their resistance to environmental and stress factors, the increase and improvement of biomass quality, as well as the increase the content of biologically active substances from plants. The paper indicates the positive aspects of using algae as a biofertilizer. We propose that when using algal biofertilizers for plant cultivation, the assessment of the structural-functional state of the edaphic algoflora of the cultivated lands should be carried out so that the species selected as biofertilizers are part of the native active algal biocenosis, develop intensively on the soil and contribute to the improvement or as appropriate, maintaining the biodiversity of edaphic algae.

Differential Membrane Lipid Profiles and Vibrational Spectra of Three Edaphic Algae and One Cyanobacterium.

The membrane glycerolipids of four phototrophs that were isolated from an edaphic assemblage were determined by UPLC–MS after cultivation in a laboratory growth chamber. Identification was carried out by 18S and 16S rDNA sequencing. The algal species were Klebsormidium flaccidum (Charophyta), Oocystis sp. (Chlorophyta), and Haslea spicula (Bacillariophyta), and the cyanobacterium was Microcoleus vaginatus (Cyanobacteria). The glycerolipid profile of Oocystis sp. was dominated by monogalactosyldiacylglycerol (MGDG) species, with MGDG(18:3/16:4) accounting for 68.6%, whereas MGDG(18:3/16:3) was the most abundant glycerolipid in K. flaccidum (50.1%). A ratio of digalactosyldiacylglycerol (DGDG) species to MGDG species (DGDG/MGDG) was shown to be higher in K. flaccidum (0.26) than in Oocystis sp. (0.14). This ratio increased under high light (HL) as compared to low light (LL) in all the organisms, with its highest value being shown in cyanobacterium (0.38–0.58, LL−HL). High contents of eicosapentaenoic acid (EPA, C20:5) and hexadecenoic acid were observed in the glycerolipids of H. spicula. Similar Fourier transform infrared (FTIR) and Raman spectra were found for K. flaccidum and Oocystis sp. Specific bands at 1629.06 and 1582.78 cm−1 were shown by M. vaginatus in the Raman spectra. Conversely, specific bands in the FTIR spectrum were observed for H. spicula at 1143 and 1744 cm−1. The results of this study point out differences in the membrane lipid composition between species, which likely reflects their different morphology and evolutionary patterns.

Antioxidant activities of some edaphic algae in Egypt

BackgroundAlgae in general characterized by their rich content of biological compounds. However, few studies were conducted on the soil-inhabiting algae and their antioxidant characteristics.ResultsThe present study was designed to evaluate the antioxidant activity of four edaphic algae including one on-soil alga (Vaucheria geminata) and three axenic isolated in-soil algae (Pleurochloris pyrenoidosa, Botrydiopsis eriensis, and Scenedesmus obliquus). Total antioxidant activity by Phosphomolybdenum assay ranged from 6.66 to 36.33 mg of Asc/g dwt; meanwhile, the percentage inhibition of DPPH radical was up to 97.37%. Antioxidant activity of each alga was assessed also by measuring their contents of total phenols, flavonoids, and pigments (chlorophyll a and carotenoids). B. eriensis and S. obliquus recorded the highest levels of phenols, flavonoids, and chlorophyll a followed by P. pyrenoidosa and V. geminata, while B. eriensis showed the highest carotenoids content. Moreover, about seven types of each phenol and flavonoid compound were identified by HPLC chromatography in the four algae under investigation. The most common detected phenols were gallic, chlorogenic, caffeic, and ferulic, while rutin, quercetin, apigenin, and quercitrin were the most abundant flavonoids among all algae under investigation.ConclusionAll the tested algae were characterized with high antioxidant activities besides the rich contents of compounds with antioxidant properties which recommend their further potential using in nutritional, pharmaceutical, and medicinal implications.

Soil Photosynthetic Microbial Communities Mediate Aggregate Stability: Influence of Cropping Systems and Herbicide Use in an Agricultural Soil.

Edaphic cyanobacteria and algae have been extensively studied in dryland soils because they play key roles in the formation of biological soil crusts and the stabilization of soil surfaces. Yet, in temperate agricultural crop soils, little is understood about the functional significance of indigenous photosynthetic microbial communities for various soil processes. This study investigated how indigenous soil algae and cyanobacteria affected topsoil aggregate stability in cereal cropping systems. Topsoil aggregates from conventional and organic cropping systems were incubated in microcosms under dark or photoperiodic conditions with or without a treatment with an herbicide (isoproturon). Physicochemical parameters (bound exopolysaccharides, organic carbon) and microbial parameters (esterase activity, chlorophyll a biomass, and pigment profiles) were measured for incubated aggregates. Aggregate stability were analyzed on the basis of aggregate size distribution and the mean weight diameter (MWD) index, resulting from disaggregation tests. Soil photosynthetic microbial biomass (chl a) was strongly and positively correlated with aggregate stability indicators. The development of microalgae crusts in photoperiodic conditions induced a strong increase of the largest aggregates (>2 mm), as compared to dark conditions (up to 10.6 fold and 27.1 fold, in soil from organic and conventional cropping systems, respectively). Concomitantly, the MWD significantly increased by 2.4 fold and 4.2 fold, for soil from organic and conventional cropping systems. Soil microalgae may have operated directly via biochemical mechanisms, by producing exopolymeric matrices surrounding soil aggregates (bound exopolysaccharides: 0.39–0.45 μg C g−1 soil), and via biophysical mechanisms, where filamentous living microbiota enmeshed soil aggregates. In addition, they may have acted indirectly by stimulating heterotrophic microbial communities, as revealed by the positive effect of microalgal growth on total microbial activity. The herbicide treatment negatively impacted soil microalgal community, resulting in significant decreases of the MWD of the conventional soil aggregates (up to −42% of the value in light treatment). This study underscores that indigenous edaphic algae and cyanobacteria can promote aggregate formation, by forming photosynthetic microbiotic crusts, thus improving the structural stability of topsoil, in temperate croplands. However, the herbicide uses can impair the functional abilities of algal and cyanobacterial communities in agricultural soils.Originality/SignificanceEdaphic algal and cyanobacterial communities are known to form photosynthetic microbial crusts in arid soils, where they drive key ecosystem functions. Although less well characterized, such communities are also transiently abundant in temperate and mesic cropped soils. This microcosm study investigated the communities’ functional significance in topsoil aggregate formation and stabilization in two temperate cropping systems. Overall, our results showed that the development of indigenous microalgal communities under our experimental conditions drove higher structural stability in topsoil aggregates in temperate cropland soils. Also, herbicide use affected photosynthetic microbial communities and consequently impaired soil aggregation.

Macrophyte disturbance alters aquatic surface microlayer structure, metabolism, and fate

Macrophytes drive the functioning of many salt marsh ecosystem components. We questioned how temporary clearing of the macrophyte community, during restoration, would impact processes at the scale of the aquatic surface microlayer. Development, deposition, and breakup of the tidal creek surface microlayer were followed over tidal cycles seasonally in a cleared "former" Phragmites marsh and an adjacent restored Spartina marsh. Metabolic and physical processes of the mobile surface microlayers and underlying water were compared, along with distribution of organic and inorganic components onto simulated plant stems. In July and October, chlorophyll-a quantities were less on simulated stems in the cleared site than in the restored site. The aquatic microlayer in the cleared site creek exhibited lower photosynthesis and respiration rates, fewer diatoms and green algae, and less chlorophyll-a. There was a lower concentration (250 times) and reduced diversity of fatty acids in the surface microlayer of the cleared site, reflecting a smaller and less diverse microbial community and reduced food resources. Fiddler crab activity was an order of magnitude higher where macrophytes had been cleared. Their consumption of edaphic algae on the mud surface may account for the reduced algae and other organics in the creek surface microlayer, thus representing a redirection of this food resource from creek consumers. Overall, there were less total particulates in the creek surface microlayer at the cleared site, and they dropped out of the surface microlayer sooner in the tidal cycle, resulting in a lower sediment load available for deposit onto marsh surfaces.

Microalgae community structure analysis based on 18S rDNA amplification from DNA extracted directly from soil as a potential soil bioindicator

Soil algae are photosynthetically active microorganisms showing changeable community structure, depending on the soil type, the agricultural practices and the application of pesticides. To characterise algal community structure, molecular approaches complementary to classical microbiological approaches based on the isolation and the culture of soil algae are required. Our study describes a polymerase chain reaction (PCR) approach targeting algal 18S rDNA sequences of desoxyribonucleic acid (DNA) samples extracted either from unialgal eukaryotic microalgae culture, complex assemblages of microalgae populations or natural soil communities. Our first results showed that microalgae rDNA can be amplified by PCR from soil DNA samples. They also indicated difficulties extracting DNA from diatoms directly from soils, probably because of the presence of robust silicate valves. An 18S rDNA library has been established and preliminary phylogenetic analysis showed the feasibility of applying molecular methods to studying edaphic algae community structure. This is promising for soil algae ecology and for developing soil biological indicators.

Edaphic algae are an important component of salt marsh food-webs: evidence from multiple stable isotope analyses

Carbon, sulfur, and nitrogen stable isotope ratios were measured in an irregularly flooded Mississippi, USA, salt marsh to evaluate the relative importance of vascular plants and algae in the food web. Primary producers had l s t inc t 6I3c values: Spartina alterniflora (hereafter Spartina) (-13%), Juncus roemerianus (hereafter Juncus) (-26Y~), and edaphic algae (-21 %o). A pure zooplankton sample, which should closely approximate the phytoplankton, had a 6I3C value of 2 3 % ~ . Values for 6 3 4 ~ ranged from 0 to +2 7~ for vascular plants, while those for edaphic algae and zooplankton were + 14 and + l 1 %I, respectively; b I 5 ~ for all primary producers ranged from +S to +6%. For 49 of the 56 (88 %) consumers sampled, 613C fell w i t h a range of -22 to -18 %o; this range centered around edaphic algae and zooplankton, but was dstlnct from the b13C of Spartina and Juncus. Values of b 3 4 ~ for 48 of the 56 (86 %) estuarine consumers ranged from +9 to +16%0, which included edaphic algae and zooplankton but was 8 to 15 36o more enriched in 3 4 ~ than Spartina or Juncus. Dual isotope plots showed the fauna to tightly cluster around values for edaphic algae and zooplankton; no consumer even moderately resembled Spartina or Juncus. This strongly suggests that the ultimate food sources for this marsh's invertebrate and fish fauna are the benthic and planktonic algae; direct contributions from vascular plants appear to be minor.

Polysaccharides in desert reclamation: Compositions of exocellular proteoglycan complexes produced by filamentous blue-green and unicellular green edaphic algae

The filamentous blue-green alga Nostoc calcicola Geitler, strain 79WA01, showed a peak production of ∼70% of its biomass as a mixture of exocellular proteoglycan complexes, containing 3–30% of a polypeptide moiety and >70% of a complex glycuronoglycan. The former contained high proportions of Asp, Glu, Arg, and amido-NH 3, in addition to ∼35% of “hydrophobic” amino-acids. The latter varied in composition in different fractions: GalA (2.5–10.3%), GlcA (4.7–11.5%), Glc (11.7–39.0%), Xyl (5.7–17.9%), Man (2.7–9.5%), Gal (5.7–9.5%), Fuc (1.5–11.1%), Ara (1.9–4.3%), and Rha (1.4–4.4%). None of the fractions showed a stoichiometric ratio of sugar residues. Palmelloid cells of three unicellular green soil-algae of the genus Chlamydomonas yielded ∼70% of their dry weight as capsular mucilage. About 50% of the sodium salt of this material was soluble in water, and contained 3–12% of polypeptide and 88–97% of glycuronoglycan (GlcA:Glc:Xyl = 1:1:3 for C. humicola Lucksch, and GlcA:Gal = 1:2 for C. peterfii Gerloff and C. sajao Lewin). These categorical differences in sugar composition, together with narrow composition distributions, suggested regular structures for the glycuronoglycans. The remainder of the mucilages contained essentially the same glycuronoglycan chains, but a higher proportion of polypeptide. These materials did not form true solutions in water, but dispersed as microgel particles.

PRIMARY PRODUCTION OF EDAPHIC ALGAL COMMUNITIES IN A MISSISSIPPI SALT MARSH1

ABSTRACTPrimary production rates of edaphic algae associated with the sediments beneath four monospecific canopies of vascular plants were determined over an annual cycle in a Mississippi salt marsh. The edaphic algal flora was dominated by small, motile pennate diatoms. Algal production (as measured by14C uptake) was generally highest in spring‐early summer and lowest in fall. Hourly rates ranged from a low of 1.4 mg C/m2in Juncus roemerianus Scheele to a high of 163 mg C/m2beneath the Scirpus olneyi gray canopy. Stepwise multiple regressions identified a soil moisture index and chlorophyll a as the best environmental predictors of hourly production; light energy reaching the marsh surface and sediment and air temperature proved of little value. Adding the relative abundances of 33 diatom taxa to the set of independent variables only slightly increased R2; however, virtually all variables selected were diatom taxa. R2was only 0.38 for the Spartina alterniflora Loisel. habitat but ranged from 0.70 to 0.87 for the remaining three vascular plant zones. Annual rates of algal production (g C/m2) were estimated as follows: Juncus (28), Spartina (57), Distichlis spicata (L.) Greene (88), and Scirpus (151). The ratio of annual edaphic algal production to vascular plant net aerial production (EAP / VPP) was 10–12% for the first three habitats and 61% for Scirpus. Chlorophyll a concentrations, annual algal production rates, and EAP / VPP values were comparable to those determined in Texas, Delaware, and Massachusetts salt marshes but lower than those reported for Georgia and particularly California marshes.

The influence of tidal flushing, light exposure and natant macrofauna on edaphic chlorophyll a in a Louisiana salt marsh

Field experiments were designed to test the effects of grass clipping and of exclusion of tidal flushing and natant macrofauna on the concentration of edaphic chlorophyll a in a Spartina alterniflora Loisel. salt marsh in southern Louisiana. The experiment was begun on 28 July 1978 and edaphic chlorophyll a was sampled on days 0, 1, 2, 8, 17 and 29. Large variations were found both over time and within the sampled area on each sample date. However, only the treatment combining grass clipping with tidal and natant macrofaunal exclusion on day 29 showed a significant difference from the control. It appears that tidal flushing is not strong enough, except perhaps during storm surges, to affect edaphic algal levels in this marsh as indicated by chlorophyll a . In addition, clipping of the grass cover was observed to result in a mat of blue-green algae which probably prevented any increase in other types of edaphic algae.

FACTORS LIMITING EDAPHIC ALGAL BIOMASS AND PRODUCTIVITY IN A GEORGIA SALT MARSH1,2

ABSTRACTA “planted core” system was developed to test the effect of short term (1–2 weeks) experimental manipulation of environmental parameters on edaphic microalgae under field conditions. A large number of small cores (surface area = 7 cm2) were collected, randomized and replanted in the marsh in fiddler crab exclosures with appropriate experimental treatments. Daily enrichment of the cores with NH4+ resulted in significant increases in edaphic primary productivity and levels of chlorophyll a in both summer and winter seasons in the short‐Spartina marsh. Enrichment with a complete nutrient solution caused no further increases. Nutrient enrichment of creekbank sediments was much less stimulatory to the resident algal assemblage. In both sites, but especially in the creekbank, the removal of fiddler crab grazers resulted in significant increases in chlorophyll a and productivity. Experimental manipulation of light intensity showed that the average light intensity reaching the sediment surface was saturating for chlorophyll production in the short‐Spartina marsh. A reciprocal transplant experiment involving unfertilized cores from the short‐Spartina marsh and creekbank marsh demonstrated that NH4+ inputs occurring in the creekbank site rapidly alleviated nitrogen limitation of edaphic algae from short‐Spartina marsh. Algae in creekbank cores incubated in the short‐Spartina marsh were unable to sustain high productivity once the original standing stock of NH4+ declined.

The Effects of a Photosynthesis Inhibitor Atrazine, on Salt Marsh Edaphic Algae, in Culture, Microecosystems, and in the Field

A 10−5 M (2.2 ppm) concentration of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) reduced the rate of photosynthesis, chlorophyll content, and cell numbers in unialgal cultures of Nitzschia sigma Grun. and Thalassiosira fluviatilis Hustedt isolated from a salt marsh habitat. Results with lower atrazine concentrations indicated an ability to maintain chlorophyll production and cell division with reduced photosynthesis. The effects of a 10−5 M concentration of atrazine in unialgal cultures were also evident in microecosystems and in the field at the same concentration, although atrazine effects were less severe in the field than in microecosystems or cultures. Cell number and productivity of the diatoms from microecosystems not treated with atrazine agreed well with field data and previously published data. Diatom species diversity was not affected by 10−5 M atrazine in microecosystems or in the field but the number of Cymatosira belgica Grun. was increased. Diatom assemblages in atrazine-treated vs non-treated microecosystems were very similar (SIMI>0.838). Results were less conclusive in the field but the trend was toward a lower level of similarity. Based on the least effect level of atrazine to diatoms, the maximum safe level for atrazine in the salt marsh is 10 ppb.

Distribution of edaphic algae as related to land usage

Abstract Species representing fifty-two algal genera were identified from surface soils collected from twenty-five disturbed and twenty-six undisturbed sites in a 17 760-acre study area. Undisturbed soils had more diverse algal populations, but smaller standing crops, than disturbed soils, even though concentrations of nitrogen and phosphorus were higher than in most disturbed soils. Disturbance of soil and changes in soil pH were primary factors which influenced algal distribution. Soil disturbance favoured development of more diverse blue-green algal flora, due to accompanying increases in soil pH. Decreased soil pH favoured dominance by green algae. Standing crops of algae decreased with soil depth at three undisturbed collection sites and algae were not present below a depth of 30 cm. Bioassays showed that phosphorus was the nutrient most limiting for algal growth in water leachates of soils.

Light, nitrogen, and phosphorus limitation of edaphic algae in a delaware salt marsh

The effects on edaphic algae associated with a pure stand of the cord grass, Spartina alterniflora Loisel of manipulating light intensity and additions of inorganic nitrogen and phosphorus as fertilizers to the marsh surface have been investigated for one year. The standing crop of edaphic algae as measured by chlorophyll a production was limited only by phosphorus supplies during fall and winter, by both phosphorus and nitrogen in spring, and only by nitrogen during the summer. Since the responses were in phase with the seasonal fluctuations in the concentration of nitrogen and phosphorus, it is concluded that the flood tide is the major source of nitrogen and phosphorus compounds for edaphic algal growth. Reduction in the quantity of light reaching the edaphic algae by Spartina cover is always a limiting factor for the standing crop. A gradient in the composition of the algal flora is directly related to light intensity, and indicates that this factor determines the relative contribution of diatoms and filamentous algae to the community. The interaction of light intensity and nutrients in regulating the production of edaphic algae and cord grass on the marsh under study over a yearly cycle has also been investigated.

Primary production of edaphic algal communities in a Delaware salt marsh1

Gross primary production of edaphic algae was estimated for five areas in a high salinity tidal marsh near Lewes, Delaware. Salt pan and bare bank (free of angiosperms) algal production did not vary significantly from one part of the year to another. Algal productivity in the tall Spartina alterniflora and Distichlis spicata areas was greatest from mid‐January to mid‐May. In the short S. alterniflora area algal productivity did not decrease in the warmest part of the year as it did in the two other grass areas. Annual cycles of light, temperature, and salinity were measured. Gross algal production was about a third of the angiosperm net production. Since much of the algal production occurs when angiosperms are dormant, it complements the pattern of angiosperm energy fixation.