انت هنا الان : شبكة جامعة بابل > موقع الكلية > نظام التعليم الالكتروني > مشاهدة المحاضرة

2 Environmental factors effect on growth microorganisms

الكلية كلية الهندسة     القسم  الهندسة البيئية     المرحلة 1
أستاذ المادة اشواق مخيف سلمان حبيب الجبوري       11/07/2018 20:09:05
The growth of microorganisms is greatly affected by the chemical and physical nature of their surroundings. An understanding of these influences aids in the control of microbial growth and the study of the ecological distribution of microorganisms. The major physical factors which affect microbial growth are solutes and water activity, pH, temperature, oxygen level, pressure and radiation.4-Oxygen Concentration: An aerobe is an organism able to grow in the presence of atmospheric O2and the ones that grow in its absence is an anaerobe. Organisms which completely are dependent on atmospheric O2 for growth are obligate aerobes. Organisms which do not require O2 for growth but do grow better in its presence are called facultative anaerobes . Aerotelerant anaerobes simply ignore O2 and grow equally well whether it is present or not. Obligate anaerobesdo not tolerate O2 at all and die in its presence. Microaerophiles are those organisms that are damaged by the normal atmospheric levels of O2 (20%) and require O2 levels between the range of 2% to 16% for growth. The different relationships with O2 appear due to several factors, including the inactivation of proteins and the effect of toxic O2 derivatives. Enzymes can be inactivated when sensitive groups .
Obligate aerobes and facultative anaerobes usually contain the enzymes superoxide dismutase (SOD) and catalase, which catalyze the destruction of superoxide radical and hydrogen peroxide respectively. Peroxidase also can be used to destroy hydrogen peroxide.
5-Pressure: Most microorganisms always are subjected to pressure of 10 atmospheres (atm). The hydrostatic pressure can reach to 600 to 1100 atm in the deep sea with temperature about 2°C to 3°C. Organisms can survive and adapt at these extreme conditions and many are barotolerant, increased pressure does adversely affect them but not as much as it does to nontolerant bacteria.
6-Radiation:
Sunlight is the major source of radiation on the earth. It includes visible light, ultraviolet radiation and radio waves. Most life is dependent on the ability of photosynthetic organisms to trap the light energy of the sun as visible light.

المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .