f_2_medium (CultureMech:000170)

Overview

External ontology

UTEX:f-2-medium (source link unavailable) — F/2 Medium

Applications

Algae cultivation
Phytoplankton culture
Microalgae research

Notes

UTEX prepares F/2 Medium from non-pasteurized seawater at 30 ppt supplemented with nitrate, phosphate, silicate, Trace Metals Solution, and three sterile vitamin stocks.

Composition

flowchart LR
    CultureMech_000170["f_2_medium"]
    ing0_Seawater_non_sterilized_["Seawater(non-sterilized)"]
    CultureMech_000170 --> ing0_Seawater_non_sterilized_
    ing1_NaNO3["NaNO3"]
    CultureMech_000170 --> ing1_NaNO3
    CHEBI_63005["CHEBI:63005"]
    ing1_NaNO3 -.-> CHEBI_63005
    ing2_Sodium_dihydrogenphosphate_monohydrate["Sodium dihydrogenphosphate monohydrate"]
    CultureMech_000170 --> ing2_Sodium_dihydrogenphosphate_monohydrate
    CHEBI_114249["CHEBI:114249"]
    ing2_Sodium_dihydrogenphosphate_monohydrate -.-> CHEBI_114249
    ing3_Na2SiO3_9H2O["Na2SiO3•9H2O"]
    CultureMech_000170 --> ing3_Na2SiO3_9H2O
    CHEBI_132108["CHEBI:132108"]
    ing3_Na2SiO3_9H2O -.-> CHEBI_132108

Ingredients (4)

#	Ingredient	Concentration	Ontology	Notes
1	Seawater(non-sterilized)		ENVO:00002149 sea water	Seawater is used to bring the recipe to its stated 1 L total volume. Its total input volume is not independently quantified; no fixed solvent concentration is asserted. The HTML specifies 30 ppt and an approximately 950 mL initial charge; the linked PDF gives 30-35 ppt.
2	NaNO3 NO3.Na 84.994 g/mol Fisher BP360-500	880 MICROMOLAR	CHEBI:63005 sodium nitrate	UTEX adds 1 mL per liter of a 7.5 g/100 mL dH2O stock.
3	Sodium dihydrogenphosphate monohydrate H2O.H2O4P.Na 137.991 g/mol MCIB 742	36 MICROMOLAR	CHEBI:114249 sodium dihydrogenphosphate monohydrate	UTEX adds 1 mL per liter of a 0.5 g/100 mL dH2O stock.
4	Na2SiO3•9H2O 9H2O.2Na.O3Si 284.198 g/mol Sigma 307815	106 MICROMOLAR	CHEBI:132108 sodium silicate nonahydrate	UTEX adds 1 mL per liter of a 3 g/100 mL dH2O stock, for 106 uM final.

Preparation

To approximately 950 mL non-pasteurized seawater at 30 ppt, add the F/2 nutrient stocks and Trace Metals Solution while stirring.
Bring the total volume to 1 L with non-pasteurized seawater at 30 ppt.
Cover and autoclave the medium or filter-sterilize it.
When cooled, add the sterile vitamin stocks.
Store at refrigerator temperature.

Solutions

Trace Metals Solution

Dose: 1 ML_PER_L

Stock composition
Ingredient	Concentration	Notes
dH2O		Water is used to bring Trace Metals Solution to 1 L total; its input amount is not separately quantified.
ZnSO4 x 7 H2O	0.023 G_PER_L	Converted from 23 mg/L in the UTEX Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.
MnSO4 x H2O	0.152 G_PER_L	Converted from 152 mg/L in the UTEX Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.
Na2MoO4 x 2 H2O	0.0073 G_PER_L	Converted from 7.3 mg/L in the UTEX Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.
CoSO4 x 7 H2O	0.014 G_PER_L	Converted from 14 mg/L in the UTEX Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.
CuCl2 x 2 H2O	0.0068 G_PER_L	Converted from 6.8 mg/L in the UTEX Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.
Fe(NH4)2(SO4)2 x 6 H2O	4.6 G_PER_L	UTEX lists 4.6 g/L in the Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.
Na2EDTA x 2 H2O	4.4 G_PER_L	UTEX lists 4.4 g/L in the Trace Metals Solution recipe. Evidence supports the stock mass column only; the source molarity column is discrepant and is not used to infer a corrected molarity or receiving-medium concentration.

UTEX adds 1 mL of this prepared stock per liter of F/2 Medium; composition values describe the stock, not final-medium concentrations. The linked stock table has an unresolved mass/molarity discrepancy; its mass column is preserved and no molarity is inferred.

Vitamin B12

Dose: 1 ML_PER_L

Stock composition
Ingredient	Concentration	Notes
dH2O		The source prepares 200 mL HEPES buffer before adding the vitamin. It does not separately quantify pure-water input; no fixed water concentration is asserted.
HEPES buffer pH 7.8	12 G_PER_L	Converted from 2.4 g/200 mL in the UTEX Vitamin B12 stock.
Cyanocobalamin	0.135 G_PER_L	Converted from 0.027 g/200 mL in the UTEX Vitamin B12 stock.

UTEX adds 1 mL of this prepared stock per liter of F/2 Medium; composition values describe the stock, not final-medium concentrations.

Biotin Vitamin Solution

Dose: 1 ML_PER_L

Stock composition
Ingredient	Concentration	Notes
dH2O		The source prepares 200 mL HEPES buffer before adding the vitamin. It does not separately quantify pure-water input; no fixed water concentration is asserted.
HEPES buffer pH 7.8	12 G_PER_L	Converted from 2.4 g/200 mL in the UTEX biotin stock.
Biotin	0.025 G_PER_L	Converted from 0.005 g/200 mL in the UTEX biotin stock.

UTEX adds 1 mL of this prepared stock per liter of F/2 Medium; composition values describe the stock, not final-medium concentrations.

Thiamine Vitamin Solution

Dose: 1 ML_PER_L

Stock composition
Ingredient	Concentration	Notes
dH2O		The source prepares 200 mL HEPES buffer before adding the vitamin. It does not separately quantify pure-water input; no fixed water concentration is asserted.
HEPES buffer pH 7.8	12 G_PER_L	Converted from 2.4 g/200 mL in the UTEX thiamine stock.
Thiamine hydrochloride	0.335 G_PER_L	Converted from 0.067 g/200 mL in the UTEX thiamine stock.

UTEX adds 1 mL of this prepared stock per liter of F/2 Medium; composition values describe the stock, not final-medium concentrations.

Target organisms and growth evidence

These are curated observations and conditions for named organisms; they do not imply universal growth suitability.

Preferred term
Tetraselmis marina
Term
Id
NCBITaxon:41888
Label
Tetraselmis marina
Growth metrics
- Measurement conditions
  F/2-medium for seven days in the first stage.
  Evidence
  Reference
  PMID:28456040
  Supports
  SUPPORT
  Snippet
  When the cells were grown in F/2-medium for seven days in the first stage, the carotenoid and lipid contents, and productivity were 44g/kg (DW), 27% and 31mg/L/d, respectively.
  Explanation
  Literature evidence states that Tetraselmis marina cells were grown in F/2 medium for seven days.
  Is max attainment
  False
- Measurement conditions
  F/2 first stage followed by three-day N-replete second stage with 4.41 mM NaNO3.
  Evidence
  Reference
  PMID:28456040
  Supports
  SUPPORT
  Snippet
  After second stage of cultivation of T. marina for further 3-days under N-replete condition (4.41mM NaNO3) increased biomass concentration of 1900mg/L and lipid content of 50% were observed
  Explanation
  Literature evidence reports increased biomass after an F/2-derived nitrogen-replete second-stage variant.
  Is max attainment
  False
Preferred term
Phaeodactylum tricornutum
Term
Id
NCBITaxon:556484
Label
Phaeodactylum tricornutum CCAP 1055/1
Strain
UTEX 642
Growth metrics
- Measurement conditions
  F/2ASW at 20 deg C, continuous illumination of 30-75 umol photons m-2 s-1, and aeration with ambient air or 1% CO2; reported mid-log harvest OD730 0.2-0.3.
  Evidence
  Reference
  DOI:10.1104/pp.18.00453
  Supports
  SUPPORT
  Explanation
  Matsui et al. explicitly report Phaeodactylum tricornutum UTEX 642 cultivation in F/2ASW.
  Is max attainment
  False
Evidence
- Reference
  DOI:10.1104/pp.18.00453
  Supports
  SUPPORT
  Explanation
  The publication supports the organism-medium relationship for the F/2ASW variant of this parent F/2 medium record.
Preferred term
Thalassiosira pseudonana
Term
Id
NCBITaxon:296543
Label
Thalassiosira pseudonana CCMP1335
Strain
CCMP1335
Growth metrics
- Measurement conditions
  F/2ASW at 20 deg C, continuous illumination of 30-75 umol photons m-2 s-1, and aeration with ambient air or 1% CO2; reported mid-log harvest OD730 0.1-0.15.
  Evidence
  Reference
  DOI:10.1104/pp.18.00453
  Supports
  SUPPORT
  Explanation
  Matsui et al. explicitly report Thalassiosira pseudonana CCMP1335 cultivation in F/2ASW.
  Is max attainment
  False
Evidence
- Reference
  DOI:10.1104/pp.18.00453
  Supports
  SUPPORT
  Explanation
  The source supports growth on the F/2ASW variant for the same strain represented by NCBI Taxonomy ID 296543 and reference assembly GCF_000149405.2.
Preferred term
Chaetoceros gracilis
Strain
UTEX LB2658
Growth metrics
- Measurement conditions
  Modified F/2ASW supplemented with sodium selenite and sodium metasilicate; sodium concentration adjusted by NaCl addition and CO2 availability varied.
  Evidence
  Reference
  DOI:10.1007/s10126-021-10037-4
  Supports
  SUPPORT
  Explanation
  Tsuji et al. report growth and CO2-concentrating mechanism experiments for Chaetoceros gracilis UTEX LB2658 using modified F/2ASW.
  Is max attainment
  False
Evidence
- Reference
  DOI:10.1007/s10126-021-10037-4
  Supports
  SUPPORT
  Explanation
  The study identifies the UTEX LB2658 strain and modified F/2ASW growth conditions; the UTEX strain page separately lists this strain as a liquid-culture Chaetoceros gracilis accession.

Recipe variants

Name
n_replete_second_stage_tetraselmis_marina
Description
F/2 culture followed by nitrogen-replete second-stage cultivation for enhanced biomass and lipid productivity of Tetraselmis marina.
Modifications
- Grow cells in F/2 medium for seven days as the first stage.
- Shift to a nitrogen-replete second stage with 4.41 mM NaNO3 for three days.
Purpose
Capture a study-specific F/2-derived nitrogen repletion variant used to increase Tetraselmis marina biomass and lipid productivity.
Evidence
- Reference
  PMID:28456040
  Supports
  SUPPORT
  Snippet
  After second stage of cultivation of T. marina for further 3-days under N-replete condition (4.41mM NaNO3) increased biomass concentration of 1900mg/L and lipid content of 50% were observed
  Explanation
  Literature evidence describes a nitrogen-replete second-stage variant after initial F/2 cultivation.
- Reference
  doi:10.1016/j.biortech.2017.04.008
  Supports
  SUPPORT
  Snippet
  N-replete condition (4.41mM NaNO3)
  Explanation
  Claims: variants[0].modifications[0:2], study-specific first-stage F/2 and second-stage nitrate concentration. Locator: abstract. Additional exact excerpt: "F/2-medium for seven days in the first stage". Retain 4.41 mM NaNO3 without conversion; the abstract separately gives the three-day second stage. The phosphorus-repletion condition is a separate experiment. This does not define the complete medium or certify a strain; original PMID evidence is preserved.
Name
f_2asw_diatom_culture
Description
F/2 artificial seawater culture conditions used for marine diatom maintenance and transformation studies.
Modifications
- Use artificial seawater supplemented with half-strength Guillard f solution.
- Maintain cultures at 20 deg C under continuous illumination at 30-75 umol photons m-2 s-1.
- Aerate cultures with ambient air or 1% CO2 depending on the experiment.
Purpose
Represent F/2ASW as a study-specific F/2 medium implementation for marine diatoms.
Evidence
- Reference
  DOI:10.1104/pp.18.00453
  Supports
  SUPPORT
  Explanation
  Matsui et al. define F/2ASW as artificial seawater plus half-strength Guillard f solution and report use with Phaeodactylum tricornutum UTEX 642 and Thalassiosira pseudonana CCMP1335. Claim: variants[1].modifications[0]. Locator: Materials and Methods / Cells and Culture Conditions. The excerpt supports this relative formulation strength only, not equivalence to the UTEX natural-seawater parent. Experimental nitrogen treatments are separate from maintenance medium. Source type: journal article; discovery: existing record reference; manually inspected full text.
  Snippet
  artificial seawater supplemented with one-half-strength Guillard’s f solution
Name
modified_f_2asw_sodium_response
Description
Modified F/2 artificial seawater used for sodium and CO2 response experiments with Chaetoceros gracilis.
Modifications
- Use the modified F/2ASW formulation in Table S1, including 1 nM sodium selenite and 0.1 mM sodium metasilicate nonahydrate.
- Adjust sodium concentration by altering NaCl addition to the basal medium.
- Vary CO2 availability to distinguish sodium-dependent growth effects.
Purpose
Capture an experimental F/2ASW variant used to study carbon concentrating mechanism physiology.
Evidence
- Reference
  DOI:10.1007/s10126-021-10037-4
  Supports
  SUPPORT
  Explanation
  Tsuji et al. report Chaetoceros gracilis UTEX LB2658 growth experiments using a modified F/2ASW formulation.
- Reference
  https://media.springernature.com/original/springer-static/esm/art%3A10.1007%2Fs10126-021-10037-4/MediaObjects/10126_2021_10037_MOESM1_ESM.pdf
  Supports
  SUPPORT
  Snippet
  0.001
  Explanation
  Claim: variants[2].modifications[0], Table S1 formulation only. Locator: page 1, Na2SeO3 row; separately quoted heading: "Trace elements (μM)". Calculation: 0.001 micromolar x 1000 nanomolar/micromolar = 1 nanomolar, not the earlier 10 nM. Sodium metasilicate nonahydrate is separately shown in the Na2SiO3.9H2O row with exact value "0.1" under "Basal seawater components (mM)". This is the complete study-specific modified artificial-seawater formulation, not two supplements added to canonical UTEX F/2. Parent DOI: 10.1007/s10126-021-10037-4. The main methods were not inspected; possible main-text/table disagreement and the existing UTEX LB2658 claim remain unverified. No parent concentrations or growth claims change.

Provenance

Timestamp	Curator	Action	Notes
2026-01-28	utex-import	Imported from UTEX Culture Collection	Source ID: f-2-medium, URL: https://utex.org/products/f-2-medium
2026-03-13T06:18:53.395564Z	culturemech-id-assigner-v1.0	Assigned CultureMech ID	Assigned stable identifier: CultureMech:000170
2026-03-17T19:45:04.333217+00:00	normalize_media_names_to_snake_case.py	NAME_NORMALIZED	Normalized name from "F/2 Medium" to "f_2_medium" for consistent matching
2026-05-09T14:15:00-07:00	culturemech-agentic-curation	ADDED_GROWTH_EVIDENCE	Added strain-specific F/2ASW and modified F/2ASW growth evidence from Falcon report review and primary literature metadata.
2026-08-06T00:58:02.514496+00:00	curate_organism_culture_type.py	SET_ORGANISM_CULTURE_TYPE	Inferred isolate: 4 specific strain(s) named, no community signal (#142)
2026-08-30T00:58:30.813745+00:00	repair_utex_ingredients.py	REPAIRED_UTEX_COMPOSITION	Restored 7 ingredient name(s) and amount(s) from a re-fetched UTEX capture. The original fetcher read fixed column positions, so the row ordinal was stored as the ingredient name, the component name as the amount, and the Amount column was never read; concentration was then filled in as G_PER_L regardless. Source: https://utex.org/pages/algal-culture-media, captured 2026-08-29T17:46:40.207779.
2026-09-06T00:00:00-07:00	repair_utex_remaining_score50.py	LINKED_UTEX_SCORE50_ALGAE_CHILDREN	Added or refreshed reciprocal parent-child link for algae/Modified_2X_CHEV_Medium.yaml.
2026-09-06T00:00:00-07:00	repair_utex_remaining_score50.py	LINKED_UTEX_SCORE50_ALGAE_CHILDREN	Added or refreshed reciprocal parent-child link for algae/f_2_nh4_medium.yaml.
2026-09-06T00:00:00-07:00	repair_utex_f2_score35.py	RESOLVED_UTEX_F2_SCORE35	UTEX prepares F/2 Medium from non-pasteurized seawater at 30 ppt supplemented with nitrate, phosphate, silicate, Trace Metals Solution, and three sterile vitamin stocks.
2026-09-06T00:00:00-07:00	repair_utex_f2_score35.py	LINKED_UTEX_F2_VARIANTS	Added or refreshed reciprocal parent-child link for algae/1_F_2_Medium.yaml.
2026-09-06T00:00:00-07:00	repair_utex_f2_score35.py	LINKED_UTEX_F2_VARIANTS	Added or refreshed reciprocal parent-child link for algae/5_F_2_Medium.yaml.
2026-09-06T00:00:00-07:00	repair_utex_f2_score35.py	LINKED_UTEX_F2_VARIANTS	Added or refreshed reciprocal parent-child link for algae/8_ppt_F_2_Medium.yaml.
2026-10-10T00:39:00.252028+00:00	codex	CURATED_UTEX_F2_INGREDIENT_AND_STOCK_STAGE_EVIDENCE	Trace-metal source mass/molarity discrepancy remains unresolved; only mass-column stock amounts are supported. The parent and 1% HTML/PDF seawater salinity versions differ; neither is silently substituted for the other. The 5% source lists vitamin doses but omits a later vitamin-addition step; no missing procedure is invented. Narrative literature variants and existing organism/growth claims are unchanged and not certified by UTEX sources. No numeric amount is invented for makeup/carrier water, seawater or the NH4MgPO4 pinch.
2026-10-10T02:50:18.663542+00:00	codex	CURATED_F2_VARIANT_FORMULATION_AND_NH4_RELATIONSHIP_EVIDENCE	The selenite correction reports Table S1 only: 0.001 micromolar = 1 nanomolar. Main methods remain inaccessible, so possible main-text/table disagreement and the existing UTEX LB2658 strain claim are not resolved. The Table S1 recipe and Matsui artificial-seawater variant are not equivalent to canonical UTEX natural-seawater F/2; no parent ingredient or stock concentration changes. The Tetraselmis evidence is abstract-level only. Phosphorus repletion is a separate experimental condition, not an added ingredient in the nitrogen-replete variant. The NH4MgPO4 pinch remains unquantified; 250 mL is flask capacity, not final medium volume. Earlier UTEX stock molarity, salinity-version, chemical catalog and missing vitamin-step issues remain open. Existing organism/growth claims and earlier curation history are unchanged. Matsui methods were manually inspected, not captured as a complete HTTP download; current browser-check failures and production reference outcomes are reported separately.