Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (676 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
A complex sulfated polymer of galactose units, extracted from Gelidium cartilagineum, Gracilaria confervoides, and related red algae. It is used as a gel in the preparation of solid culture media for microorganisms, as a bulk laxative, in making emulsions, and as a supporting medium for immunodiffusion and immunoelectrophoresis.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Where it fits in the MeSH classification
- Broader topics
- Galactans
Research landscape
PubMed indexes 10,921 records tagged with the MeSH heading “Agar” (counts retrieved 2026-10-31). 1,379 of them (12.6%) were published from 2020 onward, and the busiest period so far is through 1999 with 6,778 records.
Reviews account for 159 records (1.5%) and meta-analyses for 2. Randomized controlled trials number 21 (0.2%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 6,778 |
| 2000-2009 | 1,397 |
| 2010-2019 | 1,367 |
| 2020 onward | 1,379 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 159 | 1.5% |
| Meta-analyses | 2 | 0.0% |
| Randomized controlled trials | 21 | 0.2% |
Method: PubMed query "Agar"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in drugs and chemicals
Studies of a chemical or drug can answer very different questions: what it is and how it behaves in cells and animals, how the body handles it, and whether it changes outcomes in people. Laboratory and animal findings often do not carry over to patients, and observational studies of exposures are confounded by who uses a substance and why. Nothing on this page is a recommendation to use, avoid, start or stop any substance or medicine; talk to a qualified clinician or pharmacist about your own situation. Check the dose, the species, the comparison group and whether a patient-relevant outcome was measured.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Seaweed hydrocolloid production: an update on enzyme assisted extraction and modification technologies | 2015 | Review article Design not recorded in structured metadata | 116 | cc by PMID 26023840 · DOI · PMC4483632 |
| Spatiotemporal establishment of dense bacterial colonies growing on hard agar | 2019 | Research article Design not recorded in structured metadata | 102 | cc by PMID 30855227 · DOI · PMC6411370 |
| The speed of sound and attenuation of an IEC agar-based tissue-mimicking material for high frequency ultrasound applications | 2012 | Research article Design not recorded in structured metadata | 45 | cc by PMID 22502881 · DOI · PMC3377968 |
| Agar Composition Modulates Production of Trichoderma Peptaibols, Affecting Antibacterial and Antiproliferative Activity | 2025 | Research article Design not recorded in structured metadata | 0 | cc by PMID 40540086 · DOI · PMC12181216 |
Seaweed hydrocolloid production: an update on enzyme assisted extraction and modification technologies [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Agar, alginate, and carrageenans are high-value seaweed hydrocolloids, which are used as gelation and thickening agents in different food, pharmaceutical, and biotechnological applications.
- Closing excerpt
- This review provides an update of the detailed structural features of κ-, ι-, λ-carrageenans, agars, and alginate, and a thorough discussion of enzyme assisted extraction and processing techniques for these hydrocolloids.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (157 words)
Agar, alginate, and carrageenans are high-value seaweed hydrocolloids, which are used as gelation and thickening agents in different food, pharmaceutical, and biotechnological applications. The annual global production of these hydrocolloids has recently reached 100,000 tons with a gross market value just above US$ 1.1 billion. The techno-functional properties of the seaweed polysaccharides depend strictly on their unique structural make-up, notably degree and position of sulfation and presence of anhydro-bridges. Classical extraction techniques include hot alkali treatments, but recent research has shown promising results with enzymes. Current methods mainly involve use of commercially available enzyme mixtures developed for terrestrial plant material processing. Application of seaweed polysaccharide targeted enzymes allows for selective extraction at mild conditions as well as tailor-made modifications of the hydrocolloids to obtain specific functionalities. This review provides an update of the detailed structural features of κ-, ι-, λ-carrageenans, agars, and alginate, and a thorough discussion of enzyme assisted extraction and processing techniques for these hydrocolloids.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 26023840 · DOI · PMC4483632
Spatiotemporal establishment of dense bacterial colonies growing on hard agar [2]
Abstract reading summary — source excerpts
- Opening excerpt
- The physical interactions of growing bacterial cells with each other and with their surroundings significantly affect the structure and dynamics of biofilms.
- Closing excerpt
- Overall, the model provides a versatile platform to investigate the influences of metabolic and environmental factors on the growth and morphology of bacterial colonies.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (147 words)
The physical interactions of growing bacterial cells with each other and with their surroundings significantly affect the structure and dynamics of biofilms. Here a 3D agent-based model is formulated to describe the establishment of simple bacterial colonies expanding by the physical force of their growth. With a single set of parameters, the model captures key dynamical features of colony growth by non-motile, non EPS-producing E. coli cells on hard agar. The model, supported by experiment on colony growth in different types and concentrations of nutrients, suggests that radial colony expansion is not limited by nutrients as commonly believed, but by mechanical forces. Nutrient penetration instead governs vertical colony growth, through thin layers of vertically oriented cells lifting up their ancestors from the bottom. Overall, the model provides a versatile platform to investigate the influences of metabolic and environmental factors on the growth and morphology of bacterial colonies.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 30855227 · DOI · PMC6411370
The speed of sound and attenuation of an IEC agar-based tissue-mimicking material for high frequency ultrasound applications [3]
Abstract reading summary — source excerpts
- Opening excerpt
- This study characterized the acoustic properties of an International Electromechanical Commission (IEC) agar-based tissue mimicking material (TMM) at ultrasound frequencies in the range 10-47 MHz.
- Closing excerpt
- This characterisation enhances understanding in the use of this TMM as a tissue equivalent material for high frequency ultrasound applications.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (146 words)
This study characterized the acoustic properties of an International Electromechanical Commission (IEC) agar-based tissue mimicking material (TMM) at ultrasound frequencies in the range 10-47 MHz. A broadband reflection substitution technique was employed using two independent systems at 21°C ± 1°C. Using a commercially available preclinical ultrasound scanner and a scanning acoustic macroscope, the measured speeds of sound were 1547.4 ± 1.4 m∙s(-1) and 1548.0 ± 6.1 m∙s(-1), respectively, and were approximately constant over the frequency range. The measured attenuation (dB∙cm(-1)) was found to vary with frequency f (MHz) as 0.40f + 0.0076f(2). Using this polynomial equation and extrapolating to lower frequencies give values comparable to those published at lower frequencies and can estimate the attenuation of this TMM in the frequency range up to 47 MHz. This characterisation enhances understanding in the use of this TMM as a tissue equivalent material for high frequency ultrasound applications.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 22502881 · DOI · PMC3377968
Agar Composition Modulates Production of Trichoderma Peptaibols, Affecting Antibacterial and Antiproliferative Activity [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Current antibiotics and chemotherapeutics are becoming ineffective because pathogenic bacteria and tumor cells have developed multiple drug resistance.
- Closing excerpt
- These findings support the idea that modifying fungal cultivation parameters, the bioactivity of secondary metabolite mixtures can be tailored for specific therapeutic applications.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (226 words)
Current antibiotics and chemotherapeutics are becoming ineffective because pathogenic bacteria and tumor cells have developed multiple drug resistance. Therefore, it is necessary to find new substances that can be used in treatment, either alone or as sensitizing molecules in combination with existing drugs. Peptaibols are bioactive, membrane-active peptides of non-ribosomal origin, mainly produced by filamentous fungi such as Trichoderma spp. This study focused on producing peptaibol-rich extracts from Trichoderma atroviride O1, cultivated on malt extract agar (MA) under circadian and constant darkness conditions for 13 days. Peptaibol production was detected by MALDI-TOF mass spectrometry after six days of cultivation. The extracts demonstrated antibacterial activity against Staphylococcus aureus strains, particularly the methicillin-resistant variant, but not against the Gram-negative Pseudomonas aeruginosa. Quorum sensing interference revealed that a peptaibol-rich extract suppressed Vibrio campbellii BAA-1119's AI-2 signaling system to a degree comparable with gentamycin. Beyond antibacterial properties, the extracts exhibited notable antiproliferative activity against human ovarian cancer cells and their adriamycin-resistant subline in both 2D and 3D models. Specifically, MA-derived extracts reduced ovarian cancer cell viability by 70% at 50 μg/mL, especially under light/dark regime of cultivation. Compared to previously published results for PDA-based extracts, MA cultivation shifted the biological effects of peptaibol-containing extracts toward anticancer potential. These findings support the idea that modifying fungal cultivation parameters, the bioactivity of secondary metabolite mixtures can be tailored for specific therapeutic applications.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40540086 · DOI · PMC12181216
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Agar degradation by microorganisms and agar-degrading enzymes [5]
- Research article Primer on agar-based microbial imaging mass spectrometry [6]
- Research article Agar-based edible films for food packaging applications - A review [7]
- Research article Oligosaccharides Derived from Red Seaweed: Production, Properties, and Potential Health and Cosmetic Applications [8]
- Research article Biosynthesis of agar in red seaweeds: A review [9]
- Research article Agar oligosaccharides: A review of preparation, structures, bioactivities and application [10]
References
- Rhein-Knudsen N, Ale MT, Meyer AS. Seaweed hydrocolloid production: an update on enzyme assisted extraction and modification technologies. . 2015. PMID 26023840 · DOI · PMC4483632
- Warren MR, Sun H, Yan Y, Cremer J, Li B, Hwa T. Spatiotemporal establishment of dense bacterial colonies growing on hard agar. . 2019. PMID 30855227 · DOI · PMC6411370
- Sun C, Pye SD, Browne JE, Janeczko A, Ellis B, Butler MB, et al.. The speed of sound and attenuation of an IEC agar-based tissue-mimicking material for high frequency ultrasound applications. . 2012. PMID 22502881 · DOI · PMC3377968
- Macášek P, Kapustová A, Viktorová J, Víglaš J, Olejníková P, Grey L, et al.. Agar Composition Modulates Production of Trichoderma Peptaibols, Affecting Antibacterial and Antiproliferative Activity. . 2025. PMID 40540086 · DOI · PMC12181216
- Chi WJ, Chang YK, Hong SK. Agar degradation by microorganisms and agar-degrading enzymes. Appl Microbiol Biotechnol. 2012. PMID 22526785 · DOI
- Yang JY, Phelan VV, Simkovsky R, Watrous JD, Trial RM, Fleming TC, et al.. Primer on agar-based microbial imaging mass spectrometry. J Bacteriol. 2012. PMID 22821974 · DOI · PMC3486372
- Mostafavi FS, Zaeim D. Agar-based edible films for food packaging applications - A review. Int J Biol Macromol. 2020. PMID 32442572 · DOI
- Cheong KL, Qiu HM, Du H, Liu Y, Khan BM. Oligosaccharides Derived from Red Seaweed: Production, Properties, and Potential Health and Cosmetic Applications. Molecules. 2018. PMID 30257445 · DOI · PMC6222765
- Lee WK, Lim YY, Leow AT, Namasivayam P, Ong Abdullah J, Ho CL. Biosynthesis of agar in red seaweeds: A review. Carbohydr Polym. 2017. PMID 28325321 · DOI
- Chen X, Fu X, Huang L, Xu J, Gao X. Agar oligosaccharides: A review of preparation, structures, bioactivities and application. Carbohydr Polym. 2021. PMID 33966840 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.