A comparison of the morpho-cytology and chemical composition of the two forms of the cyanobacterium, Nostoc commune Vauch., from the Philippines and Japan

Abstract

Nostoc commune Vauch. is one of the few freshwater cyanobacteria that has been used as human food. But its commercial production has been elusive. This prompted us to investigate further on the chemical composition and morpho-cytological characteristics of the discoid and spherical forms of the alga from the Philippines and Japan. Light microscopy of the two forms revealed that they consisted of irregularly coiled, unbranched, heterocystous filaments. Transmission electron microscopy showed that a trichome was enclosed by a 14μm thick mucilaginous sheath (extracellular polysaccharide, EPS). A colonial sheath enveloped a spherical colony that was made up of a bluegreen outer core that enclosed an inner, whitish, fleshy core, while the discoid form was a deflated or desiccated form of the spherical form. Cytologically, the outer core of the spherical colony (PS) had significantly (p<0.01) shorter filaments and higher heterocyst frequency than the discoid colony while the discoid type had greater number of detached heterocysts than the other type. Chemical analyses revealed that the cyanobacterium had 34-45% oxalate-oxalic acid soluble substances (OOSS), a dietary fiber that was found to be in higher concentration among the discoid forms than the spherical forms. The major components of OOSS were identified as glucuronic and galacturonic acids that may play a role in modulating water flow in the glycans of the mucilaginous sheath. There were 17 amino acids identified. Philippine spherical (PS) colonies yielded generally higher concentration for each of these amino acids than the discoid types (PD and JD) except for phenylalanine, aspartic acid, and proline. There were six soluble proteins identified in the samples with the following molecular weights in kDa: 73, 55, 39, 36, 29, and 14.4. A protein band of 55 kDa was common to all types of colonies while 73 kDa was identified in the spherical form (PS) and faintly in the discoid form (JD). The protein bands of 39, 36, 29, and 14.4 kDa were found distinctly among the discoid forms (desiccated types) regardless of origin but absent in the spherical forms. In vitro protein digestion was improved, by as much as 30%, when the pigments were extracted. However, the presence of phenolic compounds could also affect protein digestion. Morpho-cytological studies and chemical analyses showed that N. commune of the same colony form generally had the same characteristics regardless of their origin. Although the common traits were more obviously observed among the discoid colonies. However, protein, crude lipid, and chlorophyll a concentrations were found to be more dependent on the age and culture condition of the cyanobacterium than on colony form or origin.

Bioactive phenols in algae: The application of pressurized-liquid and solid-phase extraction techniques

“…Most of them used the Folin-Ciocalteu assay for total phenols analysis (e.g. in cyanobacterium Nostoc commune [27]). There is not yet sufficient information either on individual phenols and hydroxybenzaldehydes in algae or about their physiological function in the human organism.…”

Isolation and antitumor efficacy evaluation of a polysaccharide from Nostoc commune Vauch.

“…1 It is distributed widely around the world, especially in China. 3 It has been claimed that the edible terrestrial alga has high nutritional value, because it contains abundant proteins [4][5][6][7] and dietary fibers, 6 carbohydrates, a great variety of vitamins and mineral elements, lower fat, 7,8 and other nutrients. 3 It has been claimed that the edible terrestrial alga has high nutritional value, because it contains abundant proteins [4][5][6][7] and dietary fibers, 6 carbohydrates, a great variety of vitamins and mineral elements, lower fat, 7,8 and other nutrients.…”

Healthy efficacy ofNostoc communeVaucher

“…In addition to the broad spectrum of functional properties aforementioned, there are several additional effects of N. commune and N. commune -derived extracts have been reported, such as the hypocholesterolemic function [ 5 , 20 ]. Therefore, the available reports may provide evidence that N. commune is distributed worldwide, as reviewed here, and is characterised by its great variety in both the number and type of nutrients, especially rich with various small molecules, making it an attractive natural resource treasure.…”

“…The fatty acids of N. commune are very low, accounting for only 0.21% of its dry matter [ 10 , 18 , 19 ]. N. commune also contains dietary fiber [ 5 , 20 ]. In addition, N. commune can be characterised by great variety in both the number and type of constitutive minerals, and it is especially enriched with essential elements, such as iron (Fe), zinc (Zn) and calcium (Ca) (~4‰), at significantly higher levels than in Lentinusedodes , Auriculariaauricula and Nostoc flagelliforme [ 10 , 14 , 21 , 22 ].…”

“…The difference, even diversity, obtained from different studies could be due to the orientation of N. commune and experimental methods, as well as the determination and analysis of the measurement results. Unfortunately, to date, the colonies of N. commune available in present studies are mainly field materials harvested from natural localities in contrast to limited information on the artificial culturing [ 5 ]. However, with the recent development of technology and equipment for culturing, it has become possible to obtain a sufficient sample to conduct more basic research and meet the requirements of industrial-scale applications.…”