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There are at least three hundred thousand or more species of fungi. Molds are a fungi. Mold grows the best in warm, damp, and humid conditions. Molds can spread and reproduce by making spores. Mold spores can survive harsh conditions like a dry environment. Molds are microorganisms that can be found both indoors and outdoors. Indoor mold can cause respiratory infections and fungal allergies. Indoors, mold grows where humidity levels are high like in showers or basements, because there is so much moisture. Molds outdoors grow in shady, damp areas where leaves and other vegetation is decomposing. (CDC, 2017).
Mold growth occurs when the spores settle on a surface in an environment that has the proper temperature, good food sources, and the right amount of moisture. Moisture is the main factor that allows and prevents mold to grow. Mold growth indoors is an indication of excess moisture. Causes of the excess moisture are floods,roof leaks, and plumbing problems. Other causes of moisture are temperature. Locations where warm and moist air come in contact with cool air causes water vapor to form, creating moisture. Different types of mold have minimum, optimum, and maximum temperature ranges for growth. Many fungi grow well in temperatures between 60 and 80 degrees Fahrenheit. The temperature gradients also help produce the moisture needed for mold growth. In the summer when air-conditionings are being used, mold growth occurs where the cooling systems are oversized, undersized or poorly maintained.
In the winter when buildings are being heated mold often grows in uninsulated exterior windows and walls. Temperature and moisture play a large part in the growth of mold (NC Department of Health and Human Services, 2017).
When molds are outdoors they obtain their nutrients by absorbing organic molecules from their environment. They feed off of decomposing organic material. They also secrete enzymes into their food and then proceed to absorb the already digested nutrients through their cell walls. Fungi store energy in the form of glycogen, like animals. They are very important recyclers of organic material in nature (Postlethwait and Hopson, 2009).
Indoors, many building components contain materials that are great sources of food for mold. Some of these sources include wallpaper glue, some paints, greases, paper, textiles, and wood products. Indoor dusts may contain fibers, dead skin cells, and other organic matter that can serve as a food source as well. Almost any material can act as a food source for mold, as long as there is adequate moisture available in their environment. This makes eliminating mold from your home more difficult, because mold can virtually grow anywhere that it can find a food source, good temperature, and adequate moisture (NC Department of Health and Human Services, 2017).

Molds do not need light to grow, because they do not make their own food like plants do. Molds do not have to go through photosynthesis, they get their food by feeding off of materials in homes or decomposing materials outdoors. There is however a time where most molds need light to start a different life stage, like spore production. The main reason for growing molds in the dark is that they might get dried out by the sun or other bright lights (Shepherd, 1997).
LED stands for Light Emitting Diode. Instead of having a filament to provide light, the LED light uses diodes. A diode hosts electrons moving inside of semiconductor material, which thus generates light. The light created within these diodes is a cool light, as opposed to the heated light in an incandescent bulbs filament. LED consumes little energy, therefore emitting less heat. LED burns cool and doesn’t produce as much heat as a normal light bulb (LED Lights, 2018).
The sun is the brightest and most familiar object. The color of a hot object (if it is dense) tells us how hot it is. With the sun, the color of the photosphere suggests a temperature of 5,780° Kelvin. Sunlight carries energy, which warms up the Earth. The sun is so hot and has such high radiation that it can cause skin cancer (Stern, 2006).
The basic structure of fungi/mold is they have filaments called hyphae. The cell walls of the hyphae contain chitin, a polysaccharide. The presence of chitin distinguishes cell walls of fungi from plants that contain cellulose and no chitin. A mat of hyphae that forms the body of fungus is called mycelium. In some species, cells that make up hyphae are divided by cross sections called septa.
These hyphae are called septate hyphae. Fungal species with hyphae that lack septa are called coenocytes (Postlethwait and Hopson, 2009).
Most fungi, which are mold, reproduce both sexually and asexually. Unlike most eukaryotes, most fungi are haploid throughout most of their life cycles. In asexual reproduction of fungi thousands of genetically identical haploid spores, usually on modified cells of the hyphae, are produced. When these spores are placed in favorable environmental conditions, they germinate and grow new hypha. Each of these can form a mycelium and produce thousands of new asexual spores. A variety of asexual spores are formed by different fungi. Sporangiophores are specialized hyphae that look like upright stalks. On top of a sporangiophore is a sac called a sporangium. Inside each sporangium spores called sporangiospores are made. Rhizopus is commonly found growing on bread. It is a sporangiospore-forming fungus. Conidia, which are formed without the protection of a sac are formed on top of a stalk like structure called a conidiophore. Penicillium, used to produce penicillin and types of cheeses, is a fungus that produces asexually by means of conidia. Asexual reproduction may also occur by fragmentation where a septate hyphae dries and shatters, releasing individual cells that act as spores (Postlethwait and Hopson, 2009).
Not all, but some molds can also reproduce sexually. Fungi are neither male nor female, they occur in mating types that are called minus and plus. When two different mating types of the same species encounter each other, the hyphae of one mating type fuse with the hyphae of the opposite mating type. These give rise to a specialized structure which produces and scatters genetically diverse spores.
The ability of these fungi to reproduce sexually and asexually provides an adaptive change. When the environment is favorable, rapid reproduction can ensure an increased spread of the species. When there is environmental stress sexual reproduction ensures genetic diversity. This increases the likelihood that the offspring will be well adapted to the new environmental conditions (Postlethwait and Hopson, 2009).
There are many different types of mold. Green mold is extremely common and can appear in many species of molds including three of the most common species
Penicillium, Aspergillus, and Cladosporium. Penicillium is the most common mold that appears green. Penicillium prefers moderate environments, Aspergillus is found in damp areas, and Cladosporium are commonly found in the air. Yellow mold is very toxic and can cause health problems. The most common type of yellow mold is Aspergillus. Another type of yellow mold is Serpula lacrymans, which is known for destroying wood. White mold can be Penicillium, Aspergillus, or Cladosporium. White mold can be found on virtually any material and thrives in dark and damp areas (Mold Guide, 2017).
Red mold is any mold, a fungus growing in the form of a filamentous structure called a hypha, with a reddish color at some stage of its life. To truly know what type of red mold is present it should be tested. Monascus Purpureus is a type of red mold sometimes called “red yeast”. Red mold is not harmful, however close contact should be avoided (McMahon, 2018).
In conclusion, the purpose of this experiment was to record mold growth in different lighting and determine whether mold grows fastest in dark, natural, or LED light.
In this lab experiment three different types of lighting were used. They were natural, dark, and LED light. The petri dishes containing the mold were left to grow for two weeks, being recorded every three days.
The mold in the dark lighting, trial one, had no growth on the third day. On the sixth day There were minimal amounts of small green Penicillium. On the ninth day the mold grew larger and more appeared. On the twelfth day the Penicillium grew so large they began to touchon another. On the fifteenth day the green Penicillium mold now takes up almost all of the space in the petri dish. On the eighteenth day the Penicillium grew little to not at all since the fifteenth day. The mold in dark lighting, trial two, had no growth on the third day. On the sixth day small areas of yellow ASpergillus, green Penicillium, and white Penicillium appeared. On the ninth day all three molds grew larger in diameter. On the twelfth day the white Penicillium and yellow Aspergillus have grown largely in size where they now touch. The green Penicillium has also grown greatly in size. On the fifteenth day white Penicillium grew massively in size, as well as the yellow Aspergillus. They take up half the space provided in the petri dish, two green Penicillium are now touching each other as well. On the eighteenth day all three molds have grown little, or not at all in size. In both trials observing mold growth in a dark environment there was no growth on the third day. The molds in both trials one and two grew at the same rate, producing and growing in size over the two week time period. Mold in dark environments grow quicker.
Molds do not need light for normal growth, because they do not make their own food like plants do. They have no need to go through photosynthesis to create their own food, because they get their nutrients from decomposing materials in nature or things found in a house. Sunlight dries out mold and their spores causing them not to grow at all, or fast. With mold growing in the dark the temperature is not being changed by any source of light causing the mold not to grow (Shepherd, 1997).
The mold in natural lighting, trial one, on the third and sixth day there was no mold growth visible. On the ninth day small areas of green Penicillium, larger areas of white Penicillium, and an area of red Monascus Purpureus have appeared. On the twelfth day more areas of green Penicillium have appeared and also grew in size, white Penicillium barely grew, and the red Monascus Purpureus doubled in size. On the fifteenth day all three molds grew little in size and the Monascus Purpureus spread outward. On the eighteenth day the green and white Penicillium grew immensely in size, and the Monascus Purpureus spread outward about an inch. The mold in natural light, trial two, on the third and sixth day had no mold growth visible. On the ninth day green Penicillium, white Penicillium, and yellow Aspergillus have appeared. On the twelfth day the Aspergillus has grown substantially in size, and the green and white Penicillium grew very little. On the fifteenth day all three molds grew little, or not at all in size. On the eighteenth day the Aspergillus doubled in size, while the green and white Penicillium grew little in size. The molds in both trials one and two grew at the same rate. However, the mold grown in natural light grew substantially slower than the mold grown in dark light. This is because natural light or sunlight dries out mold and their spores.
This causes the mold to either not grow or grow slowly. The light from the sun is so intense and warm that it can be too hot for the mold to grow in. This dries the mold out. When mold is dried out it doesn’t have the moisture it requires to grow. When there is no harsh light present, mold can grow faster in its ideal condition (Shepherd, 1997).
The mold in LED lighting, trial one, had no mold growth on the third and sixth day. On the ninth day a decent sized area of yellow Aspergillus, a small area of white Penicillium, and an area of mold with no color have appeared. On the twelfth day the yellow Aspergillus grew vastly in size, the white Penicillium grew little, or not at all, and the areas of mold with no color are now green which is Penicillium. On the fifteenth day the Aspergillus is a vibrant yellow and spread across the agar, while the green and white Penicillium grew little in size. On the eighteenth day the Aspergillus spread completely across the petri dish, while the green and white Penicillium have grown a minuscule amount. The mold in LED lighting, trial two, had no mold growth on the third and sixth day. On the ninth day multiple areas of tiny green Penicillium have appeared, as well as a small area of white Penicillium, yellow Aspergillus, and a small area of Monascus Purpureus. On the twelfth day the area of fuzzy white Penicillium grew massively in size, the green Penicillium doubled their original size, the Monascus Purpureus and the Aspergillus grew little in size. On the fifteenth day the green and white Penicillium did not grow at all, and the Monascus Purpureus and the Aspergillus have grown little in size. On the eighteenth day the Aspergillus and Monascus Purpureus spread vastly covering half the petri dish, while the green and white Penicillium have not visibly grown. In both trials one and two the mold grew at almost the same rate. They both had no mold growth on the third and sixth day.
The molds in both trials also spread and grew in size at about the same times and about the same amounts. The mold in LED light grew almost as fast as the mold in the dark light. Also, the mold grown in LED light grew faster than the mold in natural light. This is because LED does not produce a lot of heat. Since a lot of heat is not produced they do not change the temperature of the environment. It is almost as if the mold is growing in the dark, because it doesn’t have a strong fluorescent light that emits a lot of heat shining on it (LED Lights, 2018). Since the temperature is not being changed the mold has an adequate amount of moisture to grow and thrive. With these correct conditions the mold can grow fast. (NC Department of Health and Human Services, 2017). Also, the sun’s not shining on it causing the temperature of the environment to change, resulting in the mold drying out. (Shepherd, 1997).
In conclusion, molds are a type of fungi that grow best in warm, damp, and humid conditions. Molds can spread and reproduce by making spores. Molds are microorganisms that can be found anywhere (CDC, 2017). Mold growth can occur when it is in the proper environment with enough moisture, warm temperature, and good amount of food sources. The perfect mold growth temperature is between 60 and 80 degrees fahrenheit. The temperature also helps produce the right amount of moisture for the mold to grow in. Molds indoors feed off of many building materials such as, wallpaper, glue, wood, and dead skin cells in dust (NC Department of Health and Human Services, 2017). Outdoors molds feed off of dead decomposing materials. They also secrete enzymes into their food and then proceed to absorb the digested nutrients through their cell walls (Postlethwait and Hopson, 2009). Molds do not need light to grow. They don’t need sunlight because they are not required to go through the process of photosynthesis. They get their foods through decomposing materials outdoors or materials from buildings indoors. Molds grow best in the dark because sunlight can dry out the molds causing them not to grow or grow slowly (Shepherd, 1997). Most fungi can reproduce sexually as well as asexually (Postlethwait and Hopson, 2009). Mold grows best in the dark and LED lighting, because sunlight can affect the rate at which mold grows. (Shepherd, 1997)

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