Category Archives: Bio Science

Antibiotic sensitivity test on micro organisms.

Antibiotic means the chemical or substances origin from organisms (mainly micro organism) which act as the inhibitor of other organism. Some antibiotic kill the organism/microorganism directly and some inhibit their growth. The antibiotic sensitivity test implicates the degrees of effectiveness of any antibiotic as an inhibitor to any other organisms or microorganisms.

Requirements for Antibiotic sensitivity test:

To complete the experiment the following equipment were used

  • Cultured bacteria in test-tube and Petri dish
  • Nutrient broth
  • Micropipettes
  • Petri dish and glass rod
  • Antibiotic disc
  • Forceps and
  • Oven

Procedure of Antibiotic sensitivity test:

At first 1ml of supplied and cultured bacteria was taken in a Petri dish with the help of micropipette then the solution was spread throughout the Petri dish with the glass rod. If accidentally excess media pour into the Petri dish then the excess media with bacteria has been cast away from Petri dish and then it was covered and left for some time. After then the supplied antibiotic disc were placed into the bacteria enrich medium on the Petri dish. To observe the effectiveness of the antibiotics on bacterial growth the Petri dish was left for 24 hours at 37c in the oven.

Result and observation of Antibiotic sensitivity test:

Finally it was observed that there were rounded zones around some of the antibiotic disc and on the other hand there were no zones around some antibiotic disc.

So we can say that, the antibiotics which made quite 15mm of zone were susceptible to the supplied bacteria and the antibiotics which made the zone of less than 15mm or fail to make a zone were resistance to the bacteria.

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Discussion of Nutritive Effects of Vitamin B-Complex

Vitamin B-complex plays a very effective role in the larval, pupal and cocoon development. From this experiment it was observed that the growth of B.mori was significantly increased at all the concentration

Improved growth of various insects following vitamin supplementation has been observed by several workers.
Srivastava and Pant (1977) proved that among the vitamin B-complex group
thiamin, riboflavin, nicotinic acid pantothenic acid, pyridoxine and choline-chloride
are essential for larval growth in Dacus cucubitae. Saha and Khan (1996,
reported the effect of enrichment of mulberry leaves with vitamins
and minerals and observed that vitamins significantly increased the growth and
economic characters of B. mori L. at lower concentration to the
highest concentration produced detrimental effects on all the parameters

recorded enhanced growth due to
ascorbic acid supplementation. The absence of ascorbic acid in the diet of
first and second instars larvae B. mori resulted in poor growth and
development (Ito and Arai, 1965). They also recorded reduced pupal and
cocoon weight due to deprivation of this vitamin. The role of ascorbic acid in
the growth of silkworm larvae has also been indicated by Gomma et al.
, (1977).

Khan and Faruki (1990)
and Faruki and Khan (1992) investigated the effects of supplementation of
para- amino benzoic acid on B. mori. They observed that the vitamin
slightly increased the larval and pupal growth and cocoon characters at lower
concentrations (1 and 10 ppm) but it produced deleterious effects on adult
growth. Islam and Khan (1993) observed that mulberry leaves enriched
with manganese sulphate produced beneficial effect on the economic. Hamano and
Okand (1989)
noted that larvae of B. mori L. of a hybrid race
grew well with the diet, which contained 20-30% protein and 15-10mg of vitamin
B6. Kabila et al., 1994) also noted that aspartic and glutamic
acids increased the larval growth.


Bacteria Culture, isolation and purification

Separation of a single bacteria species from a multi species colony is known as isolation of bacteria. In nature a single type of bacteria species is usually occurs as only one component of a large and complex population containing many other organisms.

To study the characteristics of one species, that species must be isolated in pure culture. It is often helpful to use a selective method first; such a method can increase the relative proportion of the desired species in the population so that it can be more easily isolated.

A variety of techniques have been developed in isolation of bacterial colony. Some of these techniques are

  • The streak-plate technique
  • Roll tube technique
  • The pour-plate and spread-plate technique
  • Micro-manipulator technique.

We have followed the streak plate technique because it is easy and widely acceptable one.

The streak-plate technique:

The following materials and method had been used to isolate bacterial colony in streak-plate technique. Continue reading Bacteria Culture, isolation and purification

Correlation Studies Among Different Quantitative Traits of Silkworm, Bombyx mori L.

The silkworm, Bombyx mori L., most important source of natural silk has played an important role in the life of man ever since its discovery by the Chinese some 4000 years ago. It is also traditionally associated with the socio-economic life of many countries. Even today it enjoys the supremacy over all other fabrics and it is appropriately called “Queen of Textiles” for its unparallel lustre, delicacy, elasticity, crispness and artistic appearance.


According to Krishnaswami et al. (1973), the mulberry silkworm, Bombyx mori L., is the greatest source of natural silk. Generally we have two type of silkworm, viz. mulberry and non-mulberry silkworm. The silkworm larva passes trough five different stages called instars. The final or 5th instars spin to form cocoon within which the larva undergoes pupation. The cocoon shell is the source of the natural silk, which is the driest form of that secretion. Basically there are two proteins which go to form the silk fibre viz., “fibroin” which constitutes the core of the fibre and “sericin” a waxy substance which encases the fibroin.


The origin of sericulture, silk production and weaving is ancient and clouded with legend. They are closely interlinked with the emergence of China as one of the great civilizations. Chinese mythology ascribes the invention of this art to the mythical Empress Shih Xiling, the consort of the no less mythical “Yellow Emperor”, Shi Huang Ti, one of the fathers of Chinese civilization. Ancient Chinese annals give an exact date for Empress Xiling’s discovery of silkworm rearing, namely 2640 B.C. It is said that one day 14-year-old queen was enjoying a tea ceremony in her palace garden with her friends and maids under a mulberry tree, suddenly a golden coloured cocoon dropped in her teacup. When she tried to remove the cocoon from the teacup, an end of the filament comes out of the cocoon and it was a continuous one. Then she collected some more cocoons, carried them to her palace, preserved them till emergence and reared in the next generation and later invented the method of reeling (Sarkar, 1958).

Continue reading Correlation Studies Among Different Quantitative Traits of Silkworm, Bombyx mori L.

Regional Poultry Farm, Rajabarihat, Rajshashi.

Regional Poultry Farm, Rajabarihat, Rajshashi.

Govt. of the Peoples Republic of Bangladesh


Men’s can get financial benefit from those kinds of birds and the birds reproduce with the care of man is called poultry. Chickens, ducks, geese, Guinea fowl, pigeon, turkeys etc. are generally considered as poultry birds.

On the other hand details knowledge on proper reproduction of duck and hen, egg hatchling in natural and artificial methods, proper care of chickens, appropriate chicken house made methods, nutritional food, diseases prevention, product of poultry etc management is called poultry science.

Now days, poultry farms are playing very important roles in the economy of our country. So to acquire knowledge on poultry farming we went to the Regional Poultry farm, Rajabarihat, Rajshashi. The information we have collected by exchanging thoughts with the staffs of the farm have been included in this report. Continue reading Regional Poultry Farm, Rajabarihat, Rajshashi.