Bread molds by Sarah Ashfaq 51. fungi pptx

Bread Molds

1. Bread Molds Sarah Ashfaq BS 5 th semester Institute Of Botany University Of The Punjab

2. TOPIC: BREAD MOLD

3. ZYGOMYCOTA ZYGOMYCETE TRICOMYCETE CLASSES MUCORALES ENTOMOPHTHORALES GLOMALES ORDERS Rhizopus stolonifer (Bread mold)

4. Rhizopus stolonifer ( Black Bread Mold)

5. INTRODUCTION: This fungus was  first discovered by the German scientist Christian Gottfried Ehrenberg in 1818  as Rhizopus nigricans . The name was changed in 1902 to Rhizopus stolonifer by the French mycologist J. P. Vuillemin. Rhizopus stolonifer  is commonly known as  black bread mold . It is a member of  Zygomycota  and considered the most important species in the genus  Rhizopus.   It is one of the most common fungi in the world and has a global distribution although it is most commonly found in tropical and subtropical regions. [ It is a common agent of decomposition of stored foods. Like other members of the genus  Rhizopus ,  R. stolonifer  grows rapidly, mostly in indoor environments.

6. SYSTEMATIC POSITION Kingdom Fungi Phylum Zygomycota Class Zygomycete Order Mucorales Family Mucoraceae Genus Rhizopus Specie Rhizopus stolonifer

7. MUCORACEAE: Rhizopus stolonifer  is a part of the family Mucoraceae due to the key feature of a swollen extension of the sporangiophore, called the columella. It looks like a balloon within the sporangium and it often persists after the spores have been released.

8. Phylogenetic Tree: The phylogenetic tree represents that the molecular phylogeny is very similar to the current morphological grouping of the  Rhizopus  species. Rhizopus stolonifer   is located within the C cluster.  

9. GENERAL CHARACTERISTICS OF Rhizopus stolonifer (BREAD MOLD):

10. GENERAL CHARACTERISTICS OF Rhizopus stolonifer (BREAD MOLD):

11. STRUCTURE OF Rhizopus stolonifer ( Black Bread Mold): 1. They are fast-growing fungi and have a cottony appearance . 2. The body consists of branched mycelium. 3.The mycelium is coenocytic and composed of three types of hyphae; stolon, rhizoids and sporangiophores. 4. A stolon is present which is is defined as a hypha, which connects sporangiophores together. The stolon is commonly found in bread molds, and are seen as horizontally expanding across the mold.

12. STRUCTURE OF Rhizopus stolonifer ( Black Bread Mold): 5. Branching structures, called rhizoids , anchor the fungus into the substrate, releasing digestive enzymes and absorbing nutrients for the fungus. 6. The spore-producing cells within sporangia are called sporangiophores . Their function is to absorb food for growth & for spore production. 7. The black speckles that Rhizopus produces on bread are capsules, called sporangia , that the fungus produces through asexual reproduction. 8. Columella is  present on the tip of long erect stalk known as sporangiophore, present in the Rhizopus. It supports the Sporangium which has asexual spores.

13. MICROSCOPIC VIEW (SPORANGIUM):

14. REPRODUCTION IN Rhizopus stolonifer ( Black Bread Molds): Sexual Reproduction (By spore formation in the sporangia). Asexual Reproduction ( By special non-motile hyphae called sporangiophores produce sporangia that form in upright fashion).

15. ASEXUAL REPRODUCION: In asexual reproduction, special non-motile hyphae called sporangiophores produce sporangia that form in an upright fashion. The sporangia at the tips of the upright hyphae develop as bulbous black portions. Branching structures, called rhizoids, anchor the fungus into the substrate, releasing digestive enzymes and absorbing nutrients for the fungus. When conditions are good the sporangia, containing numerous haploid spores of which are produced through mitosis, release the spores into the surrounding atmosphere. These spores then may land on a moist surface and the life cycle repeats.

16. SEXUAL REPRODUCTION: The two special haploid hyphae of opposite mating types that touch due to hormones and being in close proximity of each other (gametangia). The two cytoplasm intermingle, also known plasmogamy. As this occurs the nuclei of both parents enter the conjunction , causing the resting spore to develop. Karyogamy is the term used to describe the fusion of the two nuclei. Formation of zygospore : Zygospore are thick-walled, which make them highly resistant to environmental hardships. The word zygospore comes from the Greek word zygos, which means joining. The zygospores are the only diploid phase of  Rhizopus stolonifer  reproduction.

17. SEXUAL REPRODUCTION: They are composed of two suspensor cells , which are the former gametangia or hyphae. There is a suspensor cell on either side of a large, rough, dark brown spore. After the zygospore has fully formed , meiosis occurs and haploid spores are formed and dispersed. The zygospore can become dormant for several months at a time. Meiosis still occurs and a sporangium similar to the asexually produced sporangium is created when the zygospore finally cracks open. 

18. Suspensor cells:

19. EXAMPLE: Rhizopus nigricans   is a synonym for  Rhizopus stolonifer .

20. RESPIRATION IN BREAD MOLD: Respiration in bread mold is  aerobic . Therefore, they always grow in the upper layers of the substratum so that they continue to obtain oxygen from the atmospheric air.

21. TYPES OF MOLDS THAT GROW ON BREAD : EXAMPLES:   Aspergillus Penicillium   Fusarium Mucor   Rhizopus

22. MUCORMYCOSIS: Mucormycosis (phycomycosis, zygomycosis) is an acute opportunistic infection caused by a saprophytic fungus found in soil, bread molds, and decaying fruits and vegetables. Numerous predisposing risk factors are associated with mucormycosis, although most cases have been reported in poorly controlled diabetics or in patients with hematologic malignant conditions

23. DISADVANTAGES OF EATING BREAD MOLD: Mold gives bread an off-flavor, may trigger allergic reactions and may cause harmful infections . Particularly if you have a weak immune system. Therefore, you should never knowingly eat or smell it. Some mold can produce harmful and invisible poisons called   mycotoxins . These may spread through bread, particularly when mold growth is heavy

24. How to Deter Mold Growth on Bread: To deter mold growth on bread, you can : Keep it dry.  If you see visible moisture inside the bread package, use a paper towel or a clean cloth to dry the package before sealing it. Moisture encourages mold growth. Cover it.  Keep bread covered, such as when serving it, to shield it from spores in the air. However, to avoid soggy bread and mold, don’t package fresh bread until it’s thoroughly cooled. Freeze it.  Though refrigeration slows mold growth, it also makes bread dry. Freezing bread stops the growth without altering the texture as much. Separate the slices with wax paper to make it easier to thaw only what you need.

25. CONTROL: R. stolonifer   is controlled using synthetic fungicides; among the various registered fungicides are thiabendazole, benomyl, propiconazole and thiocarbamates.  The fungicides fluodioxonyl, tebuconazole, fenhexamide and azoxystrobin have also achieved notable control of this fungus. Sanitizers like chlorine, sodium hypochlorite, calcium hypochlorite, ozone and peracetic acid have shown to have good control on  Rhizopus . Of the various non-conventional methods under experimentation, antagonists have attracted considerable attention.

26. ECONOMIC IMPORTANCE: Rhizopus stolonifer   is important economically as an agent of post-harvest storage decay. *   Saccharomyces cerevisiae   is the most important source of industrial alcohol. * R. stolonifer  and other species of  Rhizopus   also produce  ethyl alcohol which is the most important  fermentation  product.  * Rhizopus stolonifer   is also used commercially to manufacture  fumaric acid  and  lactic acid  of high purity. *The presence of   zinc reduces the amount of fumaric acid produced by the fungus .

27. REFERENCES: Webster, John; Weber, Roland (2007).  Introduction to fungi  (3rd ed.). Cambridge, UK: Cambridge university press.  ISBN   978-0-511-27783-2 .   Moore- Landecker, E. (1972).  Fundamentals of the Fungi . New Jersey: Prentice Hall.  ISBN   0133392678 .   Alexopoulos, C.J. (1952).  Introductory mycology  (2nd ed.). London, UK: Academic Press.  ISBN   9780122204029 . Benny, G.L.; Smith, M.E.; Kirk, p.m.; Tretter, E.D; White, M.M. (2016). "Challenges and Future Perspectives in the Systematics of Kickxellomycotina, Mortierellomycotina, Mucoromycotina, and Zoopagomycotina".  Biology of Microfungi . Ainsworth, G.C.; Sussman, A.S. (1965).  The Fungi An Advanced Treatise . Vol. 1. Academic Press.  ASIN   B002M3UZVM Onions, A.H.S.; Allsopp, D.; Eggins, H.O.W. (1981).  Smith's introduction to industrial mycology  (7th ed.). London, UK: Arnold.  ISBN   0-7131-2811-9 .

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