Lactobacillus – Useful BacteriaStructure-Lactobacilli are rod-shaped, Gram-positive,fermentative, organotrophs. They are usually straight, althoughthey can form spiral or coccobacillary forms under certainconditions. They are often found in pairs or chains of varyinglength. Lactobacilli are classified as lactic acid bacteria, andderive almost all of their energy from the conversion of glucoseto lactate during homolactic fermentation.Lactobacilli are commonly associated with plant herbage.althoughthermophilic strains can be comfortable attemperatures as high as 60 degrees Celsius.Habitat-the habitat of L. acidophilus can be found in manyplaces. This bacterium can be found in animal and humanintestinal tracts (for humans it is found in the gastrointestinaltract), soil, water, milk and milk products, plants, silage, andmanure. This bacteria is found in yogurt and other fermentedmilk products and is partially responsible for their sour taste.Mode of Reproduction-They have a generationtime ranging from 25 minutes to several hundred minutes, andgrow optimally between the temperatures of 30 and 40degrees Celsius. Lactobacillus acidophilus reproduces by binaryfission, a type of asexual reproduction. Binary fission is when
the bacterium doubles its contents and divides into two. It isthe primary form of reproduction for all bacteria, and can growthe colonies very quickly because each generation increasestwo fold.Useful Effects –1. Lactobacillus acidophilus is the most commonly usedprobiotic.2. Lactobacillus acidophilus inhibits the growth of harmfulbacteria.3. It helps in breaking down of food particles and helps inproduction of lactic acid and hydrogen peroxide and otherbyproducts.4. lactobacillus prevents the growth of harmful bacteria inthe digestive tract.5. Lactobacillus acidophilus produces lactase breaking downlactic acid which helps in intolerance of lactose.6. It is also used in the treatment of urinary tract infections.7. Lactobacillus bacteria can be used to treat specificoutbreaks of diarrhea and other problems, to preventdigestive problems, or to supplement the diet after takingantibiotics.
Rhinovirus- Harmful MicrobeStructure-they are among the smallest viruses, withdiameters of about 30 nanometers only.It is lytic in nature.There are over a 100 recognized types of rhinovira that differbased on their varying surface proteins.Rhinovira are amongthe smallest vira, with diameters of about only 30 nanometersThey are small, icosahedral, non-enveloped viruses containingone positive RNA strandof between 7.2 and 8.5 kb inlength.Rhinovira are composed of a capsid, that contains fourviral proteins VP1, VP2, VP3 and VP4. VP1, VP2, and VP3 formthe major part of the protein capsid. Rhinovirus attaches to thefolds in the mucous membranes of the nose (hence the namerhinovirus).Habitat -HRV survives for many hours on environmentalsurfaces. Rhinovirus types are most active in early fall, spring,and summer. Rhinoviruses can live up to 3 hours on your skin.They also can survive up to 3 hours on objects such astelephones and doorknobs. Rhinoviruses grow best attemperatures of about 91 degrees Fahrenheit, the temperatureinside the human nose. Transmission of the rhinovirus occurs inone of two ways:
Touching your skin or environmental surfaces, such astelephones and stair rails, that have the rhinovirus onthem and then touching your eyes or nose.Inhaling drops of mucus full of rhinovirus from the airwhen a contagious person coughs or sneezes.Mode of reproduction -The RV is inhaled directlyor finds its way to the nassal passage through hands that arecontaminated with the virus. The virus is then transported tothe back of the nose by the regular functioning of the noseitself. Here, the RV attaches itself to the receptors at thesurface of the nasal cells, where it reproduces. These receptorsare called Intercellular Adhesion Molecule- 1(ICAM- 1). Thereproductive cycle of the RV is 8-12 hours long. Once the cellshave been attacked, in the infected cells, the virus replicates asrapidly as possible, and continually sheds progeny viruses.These progeny viruses can propagate the infection by invadingneighboring cells. The infection remains localized in the upperrespiratory tract.Harmful Effects-When someone becomes infectedwith a rhinovirus, he or she will experience what is commonlyknown as the common cold. The symptoms usually begin 2 to 3days after infection. The symptoms of infection with this typeof virus often include:
Mucus buildup in your noseDifficulty breathing through your noseSwelling of your sinusesSneezingSore throatCoughHeadache.With a rhinovirus infection, fever is usually slight, but canclimb to 102 degrees Fahrenheit in infants and youngchildren.Symptoms can last from 2 to 14 days, but like most people,youll probably recover in about a week. An infection rarelycauses serious problems.