Characterize actinomycetes. What features of their morphology and structure of cells. The habitat and representatives.
A
ctinomycetes.
A heterogeneous collection of bacteria that form branching
filaments. The actinomycetes encompass two different groups of
filamentous bacteria: the actinomycetes per se and the
nocardia/streptomycete complex. Historically, the actinomycetes were
called the ray fungi and were thought to be related to the true
fungi, such as bread molds, because they formed mats (mycelia) of
branching filaments (hyphae). However, unlike the true fungi, the
actinomycetes have thin hyphae (0.5–1.5 micrometers in diameter)
with genetic material coiled inside as free DNA. The cell wall of
the hyphae is made up of a cross-linked polymer containing short
chains of amino acids and long chains of amino sugars. In general,
actinomycetes do not have membrane-bound cell organelles.
Actinomycetes are susceptible to a wide range of antibiotics that
are used to treat bacterial diseases, such as penicillin and
tetracycline. The mycelium in some species may break apart to form
rod- or coccoid-shaped forms. Many genera also form spores; the
sporangia, or spore cases, may be found on aerial hyphae, on the
colony surface, or free within the environment. Motility, when
present, is conferred by flagella. Many species of actinomycetes
occur in soil and are harmless to animals and higher plants, while
some are important pathogens, and many others are beneficial sources
of antibiotics. The actinomycetes include Actinomyces
itself, which forms spores on sporophores. The spores form in long
chains by segmentation or fragmentation of the sporophores. There
are also the Proactinomyces,
with a well-developed mycelium which breaks up into rods and cocci;
the Mycobacterium,
with a typical branching of the mycelium in the form of rod-like
cells which multiply by division (by segmentation); the Mycococcus,
in the form of round, irregular cells (often with lateral
protuberances, or buds), which multiply by segmentation and
gemmation; and the Micromonospora,
a group consisting of four genera (Micromonospora,
Microbispora, Micropolyspora,
and Actinobifida).
There are also forms with complex fruit-bearing organs, called
sporangia, with spores inside (Streptosporangium,
Actinosporangium,
and others), and forms which generate spores with cilia
(Actino-planes,
Dermatophilus,
and others). Actinomycetes are widely found in soil, in the silt of
bodies of water, in the air, and in plant remains. Among the
actinomycetes there are also pathogenic forms which cause
actinomycosis, tuberculosis (Mycobacterium
tuberculosis),
and diphtheria (Corynebacterium
diphtheriae).
Certain types of mycobacteria are injurious to plants, while the
Proactinomyces
forms nodules on the roots of alder trees and other plants,
contributing to their growth.
What are the molecular and structural differences between archaea and eubacteria? Give a detailed response.
According to scientists, there are six differentiated kingdoms into which living things can be divided. The eubacteria and archaebacteria are probably the least known of this categorization. Eubacteria and archaebacteria are two very different kinds of bacteria, each with their own identities and use in our daily lives. Archaebacteria are one of the oldest of organisms found on planet earth. They are composed of a single cell and are called prokaryotes. Interestingly, archaebacteria are usually found under extremes of conditions. This is not surprising considering the fact that they were one of the first organisms on earth- at a time when earth was a planet with poisonous gases and unbearable heat. The archaebacteria was one of the only organisms that could survive in that unfriendly condition. The Eubacteria are the common ones we refer to when we are generally talking about bacteria. They are complex in structure and are found under neutral conditions. You can find Eubacteria in a variety of conditions, for instance, you can find them in the human body, in some foods and practically everywhere around us. Archaebacteria are usually categorized into three groups. In the insect kingdom, these groups are called phyla. The phyla under Archaebacteria include methanogens, the halophiles and the themoacidophiles. Methanogens harvest energy by changing H2 and CO2 into methane, hence the name. The second category, the halophiles, also has a reason behind the names. Most bacteria die off under salty conditions, but that helps the halophiles thrive and prosper. Themoacidophiles thrive under acidic conditions. They also like high temperatures and can happily survive in areas that have 230degrees Fahrenheit temperatures and low ph. Eubacteria has four phyla. These are: The cyanobacteria are bacteria that are photosynthetic in nature. This means that they can use the suns energy to prepare their own food. They also release oxygen as a byproduct. These are usually found in water. Spirochetes are usually called gram negative bacteria. They may be parasites, living off the host or they may live in a symbiotic relationship with the host. Spirochetes can also live by themselves. The other group is the gram positive bacteria. This includes your friendly neighborhood bacteria producing that delicious yogurt. It is a fact that the eubacteria have been studied more extensively by human beings. There a two main reasons behind this. Archaebacteria usually live in the most hostile of environments, even in volcanic vents. For this reason, it is less practical to study them. Moreover, all the pathogens we know of are under the group called eubacteria. Also, some of these eubacteria have economic importance-for instance the lactobacillus. This has made it a more interesting subject of study. Summary:1. Eubacteria live under neutral conditions, while archaebacteria live under extremes.2. Archaebacteria are single celled creatures, while Eubacteria are more complex in nature.3. Eubacteria has been studied more by human beings because they are found in greater numbers in their environment. They have also been studied
more extensively because some have economic importance.