Nitrogen Assimilation in Actinomycetes

Published by: Nepalese Society for Microbiology 

Original Article Nepalese Journal of Microbiology (NJM), 2003, Vol 2, No 1, 2011, pp 61-65)

Nitrogen Assimilation in Actinomycetes

Kiran B Tiwari^1,2* and Upendra Thapa Shrestha^1,2

1Research Laboratory for Biotechnology and Biochemistry (RLABB), Kathmandu, Nepal

2Kantipur College of Medical Science, Sitapaila, Kathmandu, Nepal

Abstract

As actinomycetes are one of the diverse groups of soil bacteria possessing commercially useful enzymes and therapeutically useful bioactive molecules, biochemical characterization of the individual isolates is of utmost importance to understand their basic physiology. The work explored importance and optimization of nitrogen substrates in basal culture media. Besides nitrogen source, actinomycetes can use peptone as carbon source too. However, the growth will be retarded at a concentration above 0.5% of peptone. The organisms can use inorganic nitrogen but growth is pretty slow. Actinomycetes have no essential amino acid; however, organic nitrogen enhances the growth. Actinomycetes are weak acid producers. With 10mM glucose, 0.2% peptone is the optimum concentration for glucose (carbohydrate) utilization test. Hence, carbohydrate utilization test should be done in 0.2% peptone and appreciable lowering of pH should be expected at least with five days of incubation at 28ºC.

Keywords: Actinomycetes, aminoacid, nitrogen assimilation, growth optimization

Mass Spectroscopy

MASS SPECTROSCOPY

- Branch of Spectroscopy

- Analytical technique that gives information concerning the molecular structure the of organic and inorganic compounds

- It can determine molecular weight of as high as 4000

- Qualitative analytical tool to characterize different organic substances

- The quantitative analysis of mixtures (gases or liquids and sometimes solids)

- Based on the simple principle

- Yet it is a very complex and very expensive instrument

- Commonly used because of its high speed and reliability

PRINCIPLE

The compounds under investigation are bombarded with a beam of electrons which produce an ionic molecules or ionic fragments of the original species then they are separated on the basis of the difference in their masses. Suppose ionization is as follows;

M + e^- ® M⁺ + 2e^-

Where:

M⁺ = an ionized molecule

e^- = an electron

The ions are then accelerated in an electric field at voltage V. Now the energy given to each particle is eV and this is equal to the kinetic energy of the ions.

½ mn² = e V

Or n = Ö 2e V/m

Where:

n = velocity of the particle of mass, m

e = charge on an electron

m = mass of the particle

V = accelerating voltage

All the particles possess the same energy, eV. Also, all particles have the same kinetic energy, ½ mn². As the value of m varies from particle to particle, the velocity of particle in motion also changes to meet the potential energy. E.g. For a particle with mass, m₁ and n₁

½ m₁n₁²= eV

Similarly, for particles of mass m₂, m₃, m₄,………………..m_n the velocities are n₁, n₂, n₃, …………….n_n. Now their kinetic energies are:

½ m₂n₂²= eV ½ m₃n₃²= eV ½ m₄n₄²= eV………………½ m_nn_n²= eV

From above, we have;

½ m₂n₂²= ½ m₃n₃²= ½ m₄n₄²= ………………½ m_nn_n²= eV

After the charged particles have been accelerated in an applied voltage, they enter into the magnetic field, H. This field attracts the particles and move in a circular around it. The attractive force due to magnetic field is Hen, where the balancing centrifugal force on the particle is mn²/r. When the particle starts moving uniformly around the circular path the two forces become equal. i.e.

mn²/r = H.e.n

r = mn / H.e

Where, r is the radius of circular path of the particle in the motion.

From above equations;

r = [m / H.e] Ö 2eV/m

On squaring both sides;

r² = [m² / H².e²] 2eV/m

\ m/e = [H² . r²]/ 2V

The radius of circular path of the particles depends on the accelerating voltage- V, the magnetic field-H and the ratio of mass upon charge-m/e. As e, V and H are constants; the radius of ionized molecule depends on the mass only which is actually the main basis of separation of particles.

INSTRUMENTATION