Nitzschia Navis-varingica Research Articles

First record of the diatom Nitzschia navis-varingica (Bacillariophyceae) producing amnesic shellfish poisoning-toxins from Papua New Guinea

To determine the species distribution of an amnesic shellfish poisoning (ASP) toxins-producing diatom Nitzschia navis-varingica outside its current restricted geographical distribution range in Asian coastal waters, samples were collected from two sites of Bootless Bay, located on southwest coast of Papua New Guinea near Port Moresby. A total of twenty-one strains of N. navis-varingica were isolated and the clonal cultures established. The species identity was confirmed by molecular characterization based on the ribosomal DNA markers. The LSU rDNA phylogenetic inference revealed a monophyletic clade of all strains, clustered with N. navis-varingica with high bootstrap supports. ASP toxin production in the strains was investigated by HPLC with fluorescence detection and subsequently confirmed for the representative isolates by LC-MS/MS with multiple reaction monitoring (MRM) mode. All eleven strains from site A showed presence of domoic acid (DA) and isodomoic acid (IB); the toxin quota ranged from 0.70 to 4.63 pg cell−1 (average 2.75 ± 1.26 pg cell−1, n = 11), with the composition of DA and IB of 21 DA: 79 IB. While for strains from site B, four out of ten strains showed presence of DA and IB, with the toxin quota ranged from 1.40 to 3.84 (average 2.57 ± 1.17 pg cell−1, n = 4); the composition was 52 DA: 48 IB. The strains examined in this study were divided into toxic and probably non-toxic groups in ITS2 phylogeny. This represents the first record of domoic acid-producing Nitzschia navis-varingica from Papua New Guinea.

Serinicoccus kebangsaanensis sp. nov: A new bacterium isolated from the toxic diatom, Nitzschia navis-varingica

Serinicoccus kebangsaanensis sp. nov strain P2D13-UKM is a new species of Gram-positive bacteria isolated from a toxic diatom, Nitzschia navis-varingica. It is a halophilic aerobic, oxidase-negative, catalase-positive, circular, and colonies with white colour. Based on the 16S rRNA gene, the closest species were Serinicoccus profundi MCCC 1A05965 strain 0714S6-1, 97.41%, and Serinicoccus hydrothermalis strain JLT9, 97.35%. This bacteria's predominant cellular fatty acids were iso-C15: 0 (30.1 %) and iso-C16: 0 (16.2 %). The polar lipids identified in this bacterium were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, and an unknown glycolipid. The whole-genome sequence analysis of strain P2D13-UKM showed less than 85% similarity from other Serinicoccus species. The genomic DNA G + C content is 72.2 %. Here, we report the main characteristic of strain P2D13-UKM as a new species of bacteria according to its draft genome sequence, which was deposited in Gene Bank and is publicly available under the accession number VSLG00000000.

First Record of Nitzschia navis-varingica in the Sea of Marmara

We report the first occurrence of a diatom species, Nitzschia navis-varingica in the Sea of Marmara. Previously, this species was observed in the Mediterranean Sea in 2016. Samples were collected from the coast of Darıca, Istanbul, Turkey, on 22 June 2021 during a large-scale mucilage event. The species was isolated, cultured under laboratory conditions, and investigated with scanning electron microscopy and light microscopy.

Immunostimulatory and Immunomodulatory Effects of Nitzschia navis-varingica, Heterocapsa pygmaea and Chrysochromulina alifera Whole Cell Extracts on Mammalian Macrophage Cells

Microalgal species have been used as a food source and as medicine since ancient times in Africa, Mexico and China. In our study we focused on the whole cell extracts of three microalgal species that have not been studied before: the diatom Nitzschia navis-varingica, the haptophyte Chrysochromulina alifera and the dinoflagellate Heterocapsa pygmaea. Effects of the diatom Nitzschia navis-varingica, the haptophyte Chrysochromulina alifera and the dinoflagellate Heterocapsa pygmaea on mammalian macrophage cells were investigated first time in this study. A significant anti-inflammatory impact of cell extracts in distilled water was observed. Direct anti-inflammatory influence of the extracts without any solvents or further processes facilitates its usage in biotechnology. Furthermore, the ability to include these species in the human diet brings out new opportunities in terms of increasing the tolerance to certain allergic food products in patients with allergic reactions as well as inflammatory bowel disease. Moreover, these species can be used in the creams for the atopic applications on the skin to prevent skin allergies. With this study we are presenting data supporting the biotechnological potential of the diatom Nitzschia navis-varingica, the haptophyte Chrysochromulina alifera and the dinoflagellate Heterocapsa pygmaea species against inflammatory and allergic reactions.

First report of Nitzschia navis-varingica in the Mediterranean Sea and growth stimulatory effects of Nitzschia navis-varingica, Chrysochromulina alifera and Heterocapsa pygmaea on different mammalian cell types.

A benthic diatom, Nitzschia navis-varingica was found for the first time in the Mediterranean Sea. Effects of this diatom species together with the haptophyte Chrysochromulina alifera and the dinoflagellate Heterocapsa pygmaea isolated from the northeastern Mediterranean Sea coast on prostate, breast cancer and fibroblast cell lines were investigated. Algal extracts did not exert any toxic effect on these cell lines and it had growth stimulatory impact on the cells without discrimination of cell type. Our results suggest potential use of these algal extracts in tissue repair and cell growth boosting additive in the diet of humans as well as animals. Moreover, these algal extracts have potential to be used as natural resource in the skin vitalizing creams of cosmetics industry and as wound healing agents in the atopic drugs.

Diatom Nitzschia navis-varingica (Bacillariophyceae) and its domoic acid production from the mangrove environments of Malaysia

The distribution of the toxic pennate diatom Nitzschia was investigated at four mangrove areas along the coastal brackish waters of Peninsular Malaysia. Eighty-two strains of N. navis-varingica were isolated and established, and their identity confirmed morphologically and molecularly. Frustule morphological characteristics of the strains examined are identical to previously identified N. navis-varingica, but with a sightly higher density of the number of areolae per 1μm (4–7 areolae). Both LSU and ITS rDNAs phylogenetic trees clustered all strains in the N. navis-varingica clade, with high sequence homogeneity in the LSU rDNA (0–0.3%), while the intraspecific divergences in the ITS2 data set reached up to 7.4%. Domoic acid (DA) and its geometrical isomers, isodomoic A (IA) and isodomoic B (IB), were detected in cultures of N. navis-varingica by FMOC-LC-FLD, and subsequently confirmed by LC–MS/MS, with selected ion monitoring (SIM) and multiple reaction monitoring (MRM) runs. DA contents ranged between 0.37 and 11.06pgcell−1. This study demonstrated that the toxigenic euryhaline diatom N. navis-varingica is widely distributed in Malaysian mangrove swamps, suggesting the risk of amnesic shellfish poisoning and the possibility of DA contamination in the mangrove-related fisheries products.

First report of the toxigenic Nitzschia navis-varingica (Bacillariophyceae) isolated from Tebrau Straits, Johor, Malaysia

Screening of the occurrence of potentially toxic diatoms was carried out at two sites of cage cultures in Tebrau Straits, Johor. Phytoplankton samples from Sungai Pendas and Teluk Sengat were collected using a 20 μm mesh plankton net and salinity was recorded in-situ. Nitzschia and Pseudo-nitzschia cells were isolated and established into clonal cultures. All cultures were tested for domoic acid using HPLC-UV analysis and verified by LC-MS analysis. Three Nitzschia spp. and one Pseudo-nitzschia sp. were identified from these locations. Toxic and non-toxic strains of Nitzschia navis-varingica are found at the cage culture areas. Cellular toxin content in the toxic strain of N. navis-varingica is 1.8 pg cell−1. This is a new record from Malaysia and this species was isolated from estuarine water with salinity 28 PSU. The discovery of toxic Nitzschia species in Tebrau Straits indicates the potential for domoic acid accumulation in seafood.

Morphology and molecular phylogeny of Nitzschia bizertensis sp. nov.—A new domoic acid-producer

A new toxin-producing marine diatom, Nitzschia bizertensis sp. nov., isolated from the Bizerte Lagoon (Tunisia, Southwest Mediterranean Sea) is, based on studies on eight different strains, characterized morphologically by light microscopy, transmission and scanning electron microscopy, and phylogenetically using the nuclear rDNA regions: SSU, ITS1, 5.8S, ITS2 and D1–D3 of the LSU. The species belongs to the sections Lanceolatae or Lineares as defined by Cleve and Grunow (1880). These sections are characterized by species having linear-lanceolate valves with an eccentric raphe where the fibulae does not extend into the valve, and are otherwise famous for the lack of characters useful for delineation of species. Nitzschia bizertensis differs from most other species in these sections by having a high density of interstriae. The morphological and phylogenetic studies and comparisons with previously described Nitzschia species showed Nitzschia bizertensis sp. nov. to be a new species. Batch culture experiments were conducted for estimations of maximum growth rate and production of domoic acid (DA). Maximum cellular DA content of the examined strains ranged from 2×10−4 to 3.6×10−2pgcells−1. The total DA concentration (pgmL−1) was high already in exponential growth phase maybe due to reinoculation of “old” stationary phase cells, and increased into stationary growth phase where it reached a stationary level varying among the strains from ca. 4500 to 9500pgmL−1. Nitzschia bizertensis represents a new domoic acid-producing diatom and is the second toxin producing Nitzschia species. The resolution of Nitzschia bizertensis and Nitzschia navis-varingica in different parts of the LSU phylogenetic tree, and the recovery of the Pseudo-nitzschia species phylogenetically distant from those two species suggests that the ability to produce DA either evolved multiple times independently or was lost multiple times.

Unique amnesic shellfish toxin composition found in the South East Asian diatom Nitzschia navis-varingica

Nitzschia navis-varingica is a diatom that is known to produce significant levels of amnesic shellfish poisoning (ASP) toxins. A total of 33 N. navis-varingica strains were isolated from four brackish water localities in the Philippines and Indonesia, and cultured to characterize the toxins produced. The isolates were analyzed for domoic acid (DA) and isodomoic acids A (IA) and B (IB) by HPLC with fluorescence detection. Two toxin composition types were detected that have not been previously described: strains producing only IB and strains producing DA–IA–IB. These two types were isolated from two different localities. Eighteen strains were isolated from the Philippines (northern Luzon Island). Among them, 10 isolates from Alaminos produced only IB with an average toxin content of 3.05 pg cell −1, seven isolates from Bulacan produced DA and IB with average toxin contents of 0.68 pg cell −1 and 1.18 pg cell −1, respectively. One isolate from Cavite produced DA, IA, and IB with a toxin content of 0.58, 0.20, and 0.92 pg cell −1, respectively. Fifteen isolates from Indonesia (Bone, South Sulawesi) produced only DA (four isolates) or DA with trace amounts of IB (eleven isolates), with an average toxin content of 2.38 pg cell −1 and 0.06 pg cell −1, respectively. Sub-strains were established from strains producing either of the three toxin types: IB, DA–IA–IB, and DA-trace IB. Results showed that the toxin composition type was the same for parent and sub-strains, indicating that the toxin composition is a stable character for a strain.

ISOLATION OF ASP TOXIN-PRODUCING NITZSCHIA FROM THAILAND

Nitzschia navis-varingica is recognized as the major ASP toxin producer other than Pseudo-nitzschia species. Surveys on the distribution and the toxin production of this diatom has been conducted in a few countries in eastern Asia and expanded to Thailand. Eighteen isolates from Thailand showed the positive result for the ASP toxin production is DA and IB, although the ratio of IB was much lower than those of the isolates from southern countries including Okinawa, Japan, the Philippines and Vietnam.

Inorganic carbon acquisition in potentially toxic and non‐toxic diatoms: the effect of pH‐induced changes in seawater carbonate chemistry

The effects of pH-induced changes in seawater carbonate chemistry on inorganic carbon (C(i)) acquisition and domoic acid (DA) production were studied in two potentially toxic diatom species, Pseudo-nitzschia multiseries and Nitzschia navis-varingica, and the non-toxic Stellarima stellaris. In vivo activities of carbonic anhydrase (CA), photosynthetic O(2) evolution and CO(2) and HCO(3)(-) uptake rates were measured by membrane inlet MS in cells acclimated to low (7.9) and high pH (8.4 or 8.9). Species-specific differences in the mode of carbon acquisition were found. While extracellular carbonic anhydrase (eCA) activities increased with pH in P. multiseries and S. stellaris, N. navis-varingica exhibited low eCA activities independent of pH. Half-saturation concentrations (K(1/2)) for photosynthetic O(2) evolution, which were highest in S. stellaris and lowest in P. multiseries, generally decreased with increasing pH. In terms of carbon source, all species took up both CO(2) and HCO(3)(-). K(1/2) values for inorganic carbon uptake decreased with increasing pH in two species, while in N. navis-varingica apparent affinities did not change. While the contribution of HCO(3)(-) to net fixation was more than 85% in S. stellaris, it was about 55% in P. multiseries and only approximately 30% in N. navis-varingica. The intracellular content of DA increased in P. multiseries and N. navis-varingica with increasing pH. Based on our data, we propose a novel role for eCA acting as C(i)-recycling mechanism. With regard to pH-dependence of growth, the 'HCO(3)(-) user' S. stellaris was as sensitive as the 'CO(2) user' N. navis-varingica. The suggested relationship between DA and carbon acquisition/C(i) limitation could not be confirmed.

Production of isodomoic acids A and B as major toxin components of a pennate diatom Nitzschia navis-varingica

In order to obtain more detailed information on the distribution of domoic acid-producing Nitzschia in Asian waters, Nitzschia-like diatoms were isolated primarily from the Philippines and established in culture for analysis by HPLC with fluorescence detection. Out of 58 isolates, 35 Nitzschia-like diatoms from the estuary areas of San Pedro Bay, Tacloban City and Manila Bay showed significant levels of domoic acid production (1.3–5.6 pg/cell). These were identified as Nitzschia navis-varingica. Two isolates from the same locality did not produce domoic acid. Of the 21 isolates from Bulacan Estuary, Manila Bay, none produced domoic acid. They did, however, produce two substances that seemed to be domoic acid derivatives. One of the strains was mass cultured and the substances were extracted, purified and analyzed by LC-MS/MS, proton and 13C NMR, and UV spectra. The produced substances were determined as isodomoic acids A and B. This is the first report of a diatom that produces isodomoic acids A and B as major toxin components.

Wide distribution of Nitzschia navis-varingica, a new domoic acid-producing benthic diatom found in Vietnam

: Domoic acid production was screened in the Nitzschia-like strains of benthic diatom collected from Ishigaki Island (subtropical area), Tohoku District of Japan (temperate area) and Manila Bay, the Philippines (tropical area). Domoic acid was detected in 88 out of 183 strains collected from these areas. The cellular domoic acid content of these strains ranged from 0.1 to 15.3 pg/cell. All the strains positive for domoic acid production were identified as Nitzschia navis-varingica, a new domoic acid-producing benthic diatom species that was recently found in Vietnam. This species was collected only from brackish water. These results indicate that domoic acid-producing N. navis-varingica is distributed widely in brackish water from tropical to temperate areas.

Phylogeny of the Bacillariaceae with emphasis on the genus Pseudo-nitzschia (Bacillariophyceae) based on partial LSU rDNA

In order to elucidate the phylogeny and evolutionary history of the Bacillariaceae we conducted a phylogenetic analysis of 42 species (sequences were determined from more than two strains of many of the Pseudo-nitzschia species) based on the first 872 base pairs of nuclear-encoded large subunit (LSU) rDNA, which include some of the most variable domains. Four araphid genera were used as the outgroup in maximum likelihood, parsimony and distance analyses. The phylogenetic inferences revealed the Bacillariaceae as monophyletic (bootstrap support ≥90%). A clade comprising Pseudo-nitzschia, Fragilariopsis and Nitzschia americana (clade A) was supported by high bootstrap values (≥94%) and agreed with the morphological features revealed by electron microscopy. Data for 29 taxa indicate a subdivision of clade A, one clade comprising Pseudo-nitzschia species, a second clade consisting of Pseudo-nitzschia species and Nitzschia americana, and a third clade comprising Fragilariopsis species. Pseudo-nitzschia as presently defined is paraphyletic and emendation of the genus is probably needed. The analyses suggested that Nitzschia is not monophyletic, as expected from the great morphological diversity within the genus. A cluster characterized by possession of detailed ornamentation on the frustule is indicated. Eighteen taxa (16 within the Bacillariaceae) were tested for production of domoic acid, a neurotoxic amino acid. Only P. australis, P. multiseries and P. seriata produced domoic acid, and these clustered together in all analyses. Since Nitzschia navis-varingica also produces domoic acid, but is distantly related to the cluster comprising the Pseudo-nitzschia domoic acid producers, it is most parsimonious to suggest that the ability of species in the Bacillariaceae to produce domoic acid has evolved at least twice.