IWK 102 Wood Deterioration

• Deteriorate

  ◦ Being able to be attacked by deteriorating

  agents internally or externally

  ◦ To make worse

  ◦ To make inferior in quality or value

  ◦ To grow worse

  ◦ To degenerate.
• Durability is the ability of a species or a tree to resist wear and decay.
• Durability of a species or a tree may be defined as the natural resistance to biological degradation such as insects and fungi.
• Different kinds of wood vary greatly in durability due to structure and chemical components.
• Both the macroscopic and microscopic nature determine the natural durability of a species or a tree.
• Exterior factors that cause wood deteriorate: Biological factors: Bacteria, Stain Fungi, Decay Fungi, Insect, Termites, Marine Borer Non-biological factors: Thermal Degradation, Chemical Decomposition, Mechanical Wears, Climate Factors
• Bacteria are microorganisms that lack a nucleus and have a cell wall composed of a protein-sugar molecule.
• Bacteria live symbiotically with all other living organisms known to man.
• Bacteria measure to be less than 1 micron in size but reproduce to concentrations that often allow them to be visible to the naked eye.
• Bacteria are categorized as prokaryotes, which are single-celled organisms that lack a nuclear membrane.
• Bacteria have been placed in their own kingdom, Monera, because of the uniqueness of their design.
• Bacteria require carbon to survive.
• Bacteria are classified based on how they acquire the carbon necessary for survival.
• The ways bacteria affect our bodies are influenced by how they categorize themselves based on their carbon acquisition methods.
• Some bacteria use fermentation to produce the necessary nutrients needed to survive, which releases by-products such as alcohol, lactic acid, formic acid, carbon dioxide, acetic acid, and sometimes water.
• Many bacteria have protrusions from their exterior walls called pili and flagella, which are hair-like extensions that allow the bacteria to stick to objects or repel away from them, often to move toward nutrients or away from harmful toxins.
• Additionally, many bacteria will develop thick exterior walls called endospores, allowing them to endure harsh environmental conditions, attacks from viruses or anti-biotics, and long periods when nutrients are scarce.
• Bacteria reproduce asexually using a process known as binary fission, where a single chromosome that makes up the DNA of the bacteria is reproduced as an identical copy of the original, and the bacteria then splits in two, each half receiving one of the chromosomes, thus creating two identical bacteria.
• Binary fission does not allow bacteria to make the genetic changes necessary for mutation and survival in a changing environment, bacteria must utilize different evolution methods.
• Bacteria can obtain new DNA from the remains of a decomposing bacteria through a process called conjugation, where one bacteria transfers DNA to another through a tube, and by way of a viral infection known as transduction, where one bacteria creates a virus that infects another bacteria, carrying its DNA with it.
• Mechanism of Deterioration: Bacterial deterioration is very low compared to other

  biodeterioration such as fungal, insect, termite, etc.

  ◦ Bacteria is capable of attacking wood where there is very

  little or oxygen present

  ◦ Bacteria will form holes or destroy the pit membrane or

  some of the cell wall

  ◦ Permeability of wood increases by 7-10 times if attacked by

  bacteria

  ◦ Strength will reduce include toughness, compression, and

  bending

  ◦ Wood might discolour and shrinkage of wood increase

  ◦ Bacteria can attack wood that is already attacks by fungal
• Characteristic of Fungi:

  Composed of threads called hyphae

  Have no chlorophyll and cannot make their own

  food

  Require a moist environment and suitable

  temperatures to grow

  Feed by breaking down (digesting) other organisms,

  mostly plant matter (dead or living), and absorbing

  some of the digestion products

  Reproduce by spores or by division of cells

  Are important to the living world as natural

  decomposers — they release the materials of which

  living things are made so that they can be recycled.
• Molds:

  Composed of a mass of hyphae that

  penetrate the food and cause it to

  decompose.

  Some hyphae grow vertically,

  producing spore cases.

  These spore cases may make the

  mold appear grey.

  Touching the mold can cause these

  spore cases to burst, producing a

  visible cloud of spores.

  These fungi are very common and will

  attack a wide range of foodstuffs. The

  first widely used antibiotic, penicillin,

  comes from a blue mold Penicillium
• Mushrooms and Toadstools are fungi that grow through the soil or leaf litter and produce a large fruiting body with a generally characteristic shape.
• Many mushrooms and toadstools are edible, but a few are highly toxic and, as a result, caution should be exercised before eating any fungus.
• A number of species of mushrooms and toadstools are cultivated commercially.
• Both mushrooms and toadstools refer to the fruiting bodies of a fungus.
• Toadstool is the spore-bearing fruiting body of a fungus, typically in the form of a rounded cap on a stalk, especially one that is believed to be inedible or poisonous.
• Mushroom is a fungal growth that typically takes the form of a domed cap on a stalk, with gills on the underside.
• People generally use the term mushroom to describe edible fungi.
• Toadstool is used to describe inedible or poisonous mushrooms.
• All toadstools are types of mushrooms, but not all mushrooms are toadstools.
• Toadstools are most commonly represented as red, with Amanita muscaria being the most common mushroom used to represent them as a group.
• Bracket Fungi:

  The hyphae of these fungi grow through the wood of dead

  trees, causing them to rot away. The hyphae form a fruiting

  body on the surface of the log and release their spores into

  the air.
• Yeasts:

  A microscopic single-celled fungi that reproduce by

  dividing into two. Many feeds on sugars, breaking

  them down into alcohol and carbon dioxide. Used in

  baking and bread making and the production of

  alcoholic beverages. Some yeast-like fungi can cause

  disease, such as thrush.
• Pathogenic Fungi:

  Many fungi cause diseases by attacking living plants.

  ◦ These diseases include rusts, blights, and mildews.

  ◦ A few fungi attack animals, causing disease. Tinea, or

  'athlete's foot', is caused by a fungus that grows

  under the skin between the toes – where it's always

  warm and moist.
• Lichens:

  Consist of a fungus and an alga

  growing together in a close and

  mutually helpful association. The alga

  synthesizes nutrients for both, while the

  fungus gathers water.

  ◦ Look like sports or clumps of color, from

  green to brown to white to russet ret.

  ◦ Lichens can be used as biological

  indicators of air pollution.

  ◦ Lichens have no roots or protective

  surface, they cannot filter what they

  absorb, so whatever is in the air is taken

  straight inside. If there are pollutants,

  they can accumulate in the lichen and

  can become toxic very quickly.
• Gneral Characteristics of Deterioration:

  This neglected roof has obvious damage from moss

  and hidden fungal damage, evident in shake

  "cupping."
• Characteristic of Deterioration of Blue Stain:

  Some people mistakenly confuse blue stains with

  mold.

  ◦ Under the microscope, you would see that the

  stain is caused by dark-colored threads of fungus

  growing in part of the wood tissue. The threads

  are found mainly in the horizontal “ray” cells that

  the tree uses to store nutrients.

  ◦ The fungus is so intensely colored that it makes

  the whole of the wood it colonized appear

  blue/grey, even though only a few fungal

  threads may be present.
• Blue stain fungi are harmless and do not attack wood itself but live on nutrients stored in a small proportion of wood cells.