Characterization and identification of chitinase producing Streptomyces venezuelae P10.

In an attempt to isolate chitinase producers from soil, a streptomycete strain was found potent using natural chitin as the substrate. Chitinolytic activity was tested directly on agar plates, also with crude enzyme. Chitinase assay showed that the isolate could produce 0.8 U/ml of the enzyme. The morphological, cultural, physiological and biochemical characters of the isolate P10 were studied, and identified as Streptomyces venezuelae P10.

Small group discussion followed by presentation as a revision exercise at the end of a teaching module in biochemistry.

BACKGROUND: We evaluated the effect of student-dominated small group discussion followed by faculty-moderated presentation as a revision exercise after completion of a teaching module in biochemistry. We assessed the understanding of graduate medical students on the topic and the gain in retention of information, if any, after 15 days. METHODS: Small group discussions involving 11-12 students in each group were conducted on 12 application-oriented problems in 'amino acid metabolism'. A group leader among the students helped to conduct the discussions. While two-thirds of the problems were taken up after the discussion during faculty- or student-moderated interactive presentations, the remaining were not. The effects on low-, medium- and high achievers were evaluated by a pre-test and post-test with multiple choice questions immediately after the session. A subjective feedback was also obtained. To test short-term memory, a post-test with the same multiple choice questions was conducted after 15 days. RESULTS: The exercise was effective and equally beneficial for low-, medium- and high achievers. The gain was maximum when faculty moderated the presentation session. The students' retention of their gain after 15 days was complete. All the students wanted more such sessions in future. CONCLUSION: Student-dominated small group discussion followed by a faculty-moderated presentation is an effective, revision exercise for undergraduate medical students.

Survey of antimicrobial streptomycetes from soils of West Bengal: characterization and identification of potent broad spectrum antibiotic producing Streptomyces albidoflavus 321.2.

Survey of 611 streptomycetes isolates from 330 soil samples from various parts of West Bengal were done for their antimicrobial activity against Gram positive, Gram negative bacteria, unicellular and filamentous fungi. The strain 321.2 showed inhibition against all the test organisms used and found as potent. The morphological, cultural, physiological and biochemical characters were studied, compared with known species and identified as Streptomyces albidoflavus. This strain produces an antibiotic.

Optimisation of cultural conditions for antifungal antibiotic accumulation by Streptomyces rochei G164.

To induce higher amount of antifungal antibiotic production by variation of cultural parameters has been studied. The maximum effectivity was found in sucrose as carbon source, peptone as nitrogen source and at pH 7.0. The effect of other selected factors were also evaluated in order to judge the variables that influenced antibiotic production.

Characterisation and identification of broad spectrum antibiotic producing Streptomyces hygroscopicus D 1.5.

A streptomycete strain D1.5 capable of producing broad spectrum antiobiotic was isolated from soil. The morphological, cultural, physiological and biochemical characters were studied, compared to known species and identified as Streptmoyces hygroscopicus. Antibiotic activity of the strain was tested against both Gram positive and negative bacteria as well as fungi. It exhibited complete resistance to beta-lactum antibiotics.

Effect of different fractions of petroleum ether (60-80 degrees) extract of the seeds of Lagerstroemia speciosa (Linn. ex Murray) Pers. on some microorganisms.

In a model experiment, seed extracts were applied to different bacterial test organisms. Different fractions of seed extracts in petroleum ether (60-80 degrees C) of Lagerstroemia speciosa (Linn. ex. Murray) Pers. when applied to both Gram positive and Gram negative test bacteria, some fractions showed high antagonistic activity.

Effect of different fractions of methanolic extract of the seeds of Dolichos biflorus on some microorganisms.

Extracts from different parts of plants (1) including seeds are reported to act upon pathogenic microorganisms. A few active principles were isolated. The present preliminary report shows significant role of the seeds of Dolichos biflorus (Linn), locally known as Kulthi, against some test organisms using different fractions of defatted seed extracts with methanol.

Screening and identification of antibiotic producing strains of Streptomyces.

About 450 actinomycetes were isolated from nearly 100 soil samples collected from different parts of West Bengal. The isolates were screened on the basis of their inhibitory effect against test organisms. Finally two potent antibiotic producers were chosen having maximum inhibitory effect on both gram positive and gram negative test bacteria. On the basis of morphological, structural, physiological and biochemical characters, the two potent antibiotic producers were identified as Streptomyces violaceus-niger and S. antibioticus.

Isolation and cloning of Bacillus thuringiensis var Kurstaki HD73 toxin gene and construction of a chimaeric gene for expression in plants.

Necessity for the production of transgenic crop plants of India, capable of expression of insecticidal Bt protein in plant to combat lepidopteran pest damage has been strongly felt. Bacillus thuringiensis Kurstaki HD73 crystal protein coded by CryIA(c)73 gene has been found to be sufficiently effective against the major pests of jute and chickpea. An attempt to isolate the gene and make its use in a chimaeric gene construct for expression in plant was carried out. The plasmid CryIA(c)73 gene was cloned and tailored at the 3' end. The expression of the truncated gene was monitored in the minicell systems of E. coli. The entomocidal property was found to be fully retained by the gene product. Deletion of the nucleotides at the 5' end was carried out and chimaeric gene construct of cryIA(c)73 was made in such a way that it was fused in frame with GUS gene under the control of the caMV 35S promoter with Nos polyadenylated terminus. Such a chimaeric gene construct was used as the passenger of a Ti plasmid derived plant vector with kanamycin gene (NPTII) as the additional plant marker. Transformation through infection of tobacco and mustard plant cells in culture was carried out. Plants regenerated from the transformed cells showed the presence of GUS gene indicating the expression of the cloned fused gene. Also, Northern analysis established the presence of cryIA(c)73 gene transcripts in the transgenic plants.

Interaction of T-DNA border sequences and Ti-plasmid vir functions of Agrobacterium results in differential single-stranded linear T-DNA molecule production and plant transformation.

The mechanism of Agrobacterium mediated genetic transformation of plants is dependent upon certain genetic function of the chromosome of the bacterium as well as on Ti-plasmid borne vir loci and the border sequences of T-DNA. The organisationally variable forms of the naturally occurring border sequences amongst Ti-plasmid types are differentially responsive to gene products of vir loci concerned with T-strand production. Additionally, the production of stable transformants is dependent upon vir gene products effective after T strands are produced. The interaction of border sequences from different strains of Agrobacterium with vir proteins encoded by various helper plasmids revealed that functional differences do exist amongst vir gene products contained in the type of helper plasmids used.