Lichens are the symbiotic associated organisms which forms the association between fungus and photosynthetic substances. Their aqueous extract produce vast number of secondary metabolites with varying biological activities including antibiotic, anti-mycobacterial, antiviral, anti-inflammatory, anti-proliferative and cytotoxic effects against various diseases. Lichens can be of following types : Based on the substrate of growing. 01) Corticolous (grows on tree barks), 02) Follicolous (grows on leaves surfaces), 03) Saxicolous (grows on rock surfaces), 04) Terricolous (grows on soil) 05)Musicolous (grows on mosses)

1. Lichens
Main Features and Applications
Dinithi Vihanga De Silva

2. Content
 What is lichen?
 General features of lichen
 Applications of lichens
 Examples of the Lichen Applications
 Example indicating the photobiont and microbiont
 References

3. What is lichens ?
Figure 01 – different types of lichens
Lichen is a symbiotic
organism composed of a
fungus with a photosynthetic
partner usually either a green
algae or cyanobacterium.
(Jayanthi, S., et al. 2012. )

4. General features of lichens
 The major portion of the thallus is occupied by the fungal component and that fungal component
produces its own reproductive structures.
 The algal partner makes the food by the process of photosynthesis. The food diffuses out and is
absorbed by the fungal partner.
 Owing to their symbiotic relationship, lichens can live in variety of habitats and climatic conditions
including extreme environments.
 the lichens can be of following types : Based on the substrate of growing.
01) Corticolous (grows on tree barks),
02) Follicolous (grows on leaves surfaces),
03) Saxicolous (grows on rock surfaces),
04) Terricolous (grows on soil)
05)Musicolous (grows on mosses)
 Lichen growth forms are generally visible on surfaces forming grayish, greenish or orange areas.
They are classified into three major types depending on their morphology and size.
i) Fruticose ( shrubby ) ii) Foliose ( leaf like) iii) Crustose ( like crusts)

5.  Crustose are called as micro-lichens & fruticose & foliose lichens are also called as
macro-lichens.
 The lichen’s plant body is called as thallus. Thallus is the vegetative portion and is
similar to the vegetative portions of mosses and liverworts.
 Mycobiont (Ascomycete or Basidiomycete) establishes an intimate symbiotic
relationship with phycobiont (green algae or blue green algae). After association, both
phycobiont and mycobiont lose tsheir uniqueness and they are known as lichens.
Morphologically and physiologically lichens act as a single organism.
 The reproduction methods of lichens are completely different from fungi and algae.
Vegetative reproduction of lichens is through diaspores .The most common diaspores
are soredia and isidia.
 The fungal partner of the lichens reproduces sexually. Sexual reproduction in the
lichens is initiated by the production of fruiting bodies followed by formation of spores
called as ascospores. Ascospores are resting spores which have the ability to tolerate
adverse conditions.

6.  Lichens are formed through symbiosis between a fungal and
a photosynthetic partner such as algae or cyanobacteria.
 More than 17,000 species and over 800 lichen products are
known to be utilized by mankind eg., for dying, pollution
monitoring, perfumery, floral decorations, as well as for
dietary and medicinal purposes (Ingolfsdottir, 2002).
 Components such as usnic acid are utilized for perfumery
and for medicinal purposes (Huneck, 1999).
Applications of Lichens

7.  The aqueous extract of lichens produce a number of secondary metabolites
with varying biological activities including antibiotic, anti-mycobacterial,
antiviral, anti-inflammatory, analgesic, antipyretic, anti-proliferative and
cytotoxic effects against various diseases. ((Jayanthi, S., et al. 2012. )
 Secondary metabolites produced by lichens are used to monitor air pollution,
food for humans and animals, and also control the biodetoriation problems. It
has a potential application in the field of natural dyeing.
 The drug derived from the secondary metabolites of lichen, usnic acid has a
potential effect in cancer therapy due to its antimitotic and antiproliferative
action. ((Jayanthi, S., et al. 2012. )
 The antioxidant property of secondary metabolites plays a major role in
treatment of various diseases. This review will summarize the origin, types,
secondary metabolites and applications of some lichens.((Jayanthi, S., et al.
2012. )

8. Examples of the Lichen Applications
1) Ingredients in Perfumes and Deodorants
2) Antibiotics, Preservatives, and Toxins
3) A Useful Dye and an Interesting Pigment
4) Dyes for Wool and Fabric
5) Lichens Historically Used as Food
6) Pollution and Dehydration
7) Radiation Exposure

9. 01) Ingredients in Perfumes and
Deodorants
02) Antibiotics, Preservatives, and
Toxins
 Usnea- natural medicine, Usnea is used as an
antibiotic and an anti-inflammatory substance.
Usnea is also used in some products as a
preservative.
 The wolf lichen (Letharia vulpina) has a bright
yellow-green colour & contains a yellow chemical
called vulpinic acid, which is poisonous to
mammals & used for dye extraction. Lab research
shows that vulpinic acid can kill certain kinds of
bacteria.
 Microcystins in Nostoc-
That toxins can cause
liver damage in
humans and other
animals when they are
sufficiently
concentrated.
 Oakmoss (Evernia prunastri) is used to
provide scents and fixatives for perfumes.
Both essential oils and absolutes are
extracted from the oakmoss.
 Pseudevernia furfuracea is another
fruticose lichen used in the perfume
industry. The lichen was used to fill the
body cavity of Ancient Egyptian mummies.
Figure 02- lichen perfumes
Figure 03- usnea presavatives

10. 03) A Useful Dye and an
Interesting Pigment
04) Dyes for Wool and Fabric
 Many lichens are a grey colour when they're
dry. When a lichen is moistened and absorbs
water, however, the algal cells give it a
deeper hue.
 The fungus component is often colourless,
but in some cases it contains a pigment that
gives the lichen a vivid color.
 Making wool and fabric dyes from lichens is
an ancient process that is still performed
today.
Litmus Paper- Litmus paper is used as an acid-
base indicator. Litmus is a mixture of dyes
extracted from specific lichens, especially Rosella
tinctoria. Litmus paper is made from filter paper
that has been treated with the dye.
Natural Sunscreens- Xanthoria parietina is a
foliose lichen which contains a yellow pigment
called parietin. This pigment absorbs ultraviolet
radiation, acting as a sunscreen to protect the
algal cells inside the lichen.
figure 04- Xanthoria parietina lichen
Figure 05- lichen dyes

11. 05) Lichens Historically Used as Food
 A few species have been eaten by humans
 Reindeer moss, or Cladonia rangiferina, is a
fruticose lichen that is a staple food of reindeer and
caribou
 Some groups boiled specific species of lichens and
before eating they mix different kinds of berries etc.
Figure 06- Lichen bread and
edible lichen
 Umbilicaria esculenta is a black foliose lichen that
grows on rocks. It has been used in Asian cuisine
after being fried. In North America, they were used
as an emergency food by early explorers after being
properly prepared.

12.  Lichens are a small group of curious plants of composite nature made up
of two different organisms,
01) an alga (phycobiont: in Latin phycos-alga; bios-life)
02) a fungus (mycobiont: in Greek mycos-fungus; bios-life).
 Algal and fungal components live in a truly intimate symbiotic
relationship.
 This true nature of lichens was first identified by Simon Schwendener. He
named the algal component as Phycobiont and the fungal component as
Mycobiont.

13. Figure 07 –Hypogymnia physodes lichen photograph
captured on 18/07/2020 , location – Mandaram Nuwara , Sri Lanka
Phycobiont- Lecanorales
Mycobiont – Ascomycota
Type - Foliose

14. Phycobiont - Lecanorales
Mycobiont – Ascomycota
Figure 08 – Parmelia sulcata lichen photograph
Captured on 19/07/2020 : Piduruthalagala forest reserve,Sri
Lanka
Type - foliose

15. Phycobiont – Verrucariales
Mycobiont – Ascomycota
Figure 09 – Endocarpon pusillum lichen
Type - crustose

16. References:
 Hale, M.E., 1967. The biology of lichens. The biology of lichens.
 Lisci, M., Monte, M. and Pacini, E., 2003. Lichens and higher plants on stone: a review.
 International Biodeterioration & Biodegradation, 51(1), pp.1-17.
 Jayanthi, S., Priya, P., Monica Devi, D. and Benila Smily, J.M., 2012. Lichens: Origin, types,
secondary metabolites and applications. J. Acad. Ind. Res, 1, pp.45-49.
 Podterob, A.P., 2008. Chemical composition of lichens and their medical applications.
Pharmaceutical Chemistry Journal, 42(10), pp.582-588.
 https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(OpenStax)/05%3A_Th
e_Eukaryotes_of_Microbiology/5.5%3A_Lichens
 https://www.studyandscore.com/studymaterial-detail/general-characters-of-lichens

17. Acknowledgement

18. Thank you