Tag: bacteria; benefits and harmful effects

Azotobacter has a wide variety of metabolic abilities, including the unusual ability to fix atmospheric nitrogen as they produce nitrogenase enzyme and convert it to ammonia. They are free living in soil and do not associate as symbionts. 

Fermentation is a process of anaerobic respiration that converts sugar to acids, gasses or alcohol. It occurs in yeast and bacteria, but also in oxygen-starved muscle cells, as in the case of lactic acid fermentation. The food processing industry depends on this phenomenon for deriving a variety of edible products and beverages. As viruses are the acellular organism, they do not follow respiration. Protista are the eukaryotic unicellular and respire like animals. Thus, the correct answer is option D.

Some bacteria can fix atmospheric nitrogen, e.g., Azotobacter and Clostridium, while others convert ammonia into nitrate, e.g., Nitrosomonas.
A biogeochemical cycle or substance turnover or cycling of substances is a pathway by which chemical nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, and water etc move through both biotic and abiotic compartments of earth. All of these are required to carry out basic life processes as these processes supply with energy and nutrients. Thus, the correct answer is option D.

Cyanobacteria, which have "symbiotic" relationships with cycads are in the order Nostocales. Anabaena cycadeae is a blue green algae (BGA) commonly found in the coralloid roots of cycads. At first, the cycad sprouts without any cyanobacterium. Coralloid roots are formed soon after the primary root.
So answer is - 'Cycas'.

Heterotrophic bacteria require an organic carbon source for growth (i.e., they derive energy and carbon from organic compounds). Economically important uses of heterotrophic bacteria are:

1. They enhance the fertility of the soil by nitrogen fixation.
2. Production of curd and yogurt from milk, cheese, butter, wine
3. Production of antibiotics
4. They form an essential part of biogeochemical cycles during which they release essential elements, such as nitrogen and carbon for recycling.
5. Cleaning of oil spills

Bacteria which directly convert atmospheric nitrogen into nitrogen compounds are called nitrogen fixing bacteria. They could be symbiotic or free- living like Rhizobium and Azotobacter respectively.
So answer is -'Nitrogen fixing bacteria'.

A chemoorganotroph is an organism, that obtains energy from the oxidation of reduced organic compounds. The list of compounds from which chemoorganotrophic organisms can generate energy and their sources of carbon is very long, making these microorganisms extremely versatile. Two mechanisms for energy conservation are known for chemoorganotrophs: fermentation and respiration.
So answer is - 'Chemoorganotrophs'.

Typhoid is a bacterial infection that is caused by the bacteria Salmonella typhi. Symptoms include high fever, diarrhea, vomiting, headache, abdominal pain. It is spread by food or water contaminated with the feces of an infected person. 

Citrus canker is a plant disease caused by the bacterium Xanthomonas citri.

Denitrification is the biological conversion of nitrate to nitrogen gas, nitric oxide or nitrous oxide.  These compounds are gaseous compounds and are not readily available for microbial growth; therefore they are typically released to the atmosphere. Denitrifiers belong to several genera including Pseudomonas,Bacillus, Spirillum, Hyphomicrobium, Propionobacterium, Cornebacterium, Thiobacillus, and Alcaligenes. Biological denitrification is an anaerobic respiration reaction in which nitrate is reduced. Denitrifying bacteria are aerobic autotrophs or heterotrophs that can switch to anaerobic growth when nitrate is used as an electron acceptor.
 So, the answer is option C.