Characterization and low-cost preservation of Chromobacterium violaceum strain TRFM-24 isolated from Tripura state, India.

BACKGROUND: Chromobacterium species, through their bioactive molecules, help in combating biotic and abiotic stresses in plants and humans. The present study was aimed to identify, characterize and preserve in natural gums the violet-pigmented bacterial isolate TRFM-24 recovered from the rhizosphere soil of rice collected from Tripura state. RESULTS: Based on morphological, biochemical and 16S rRNA gene sequencing, the isolate TFRM-24 was identified as Chromobacterium violaceum (NAIMCC-B-02276; MCC 4212). The bacterium is saprophytic, free living and Gram negative. The strain was found positive for production of IAA, cellulase, xylanase and protease, and showed tolerance to salt (2.5%) and drought (-1.2 MPa). However, it showed poor biocontrol activity against soil-borne phytopathogens and nutrient-solubilizing abilitiets. C. violaceum strain TRFM-24 did not survive on tryptic soya agar (TSA) beyond 12 days between 4 and 32 °C temperature hence a method of preservation of this bacterium was attempted using different natural gums namely Acacia nilotica (babul), Anogeissus latifolia (dhavda), Boswellia serrata (salai) and Butea monosperma (palash) under different temperature regime (6-32 °C). The bacterium survived in babul gum (gum acacia), dhavda and salai solution at room temperature beyond a year. CONCLUSION: Based on polyphasic approach, a violet-pigmented isolate TRFM-24 was identified as Chromobacterim violaceum which possessed some attributes of plant and human importance. Further, a simple and low-cost preservation method of strain TRFM-24 at room temperature was developed using natural gums such as babul, dhavda and salai gums which may be the first report to our knowledge.

Rapid high throughput template preparation (rHTTP) method: a novel cost effective method of direct PCR for a wide range of plants.

BACKGROUND: Conventional plant DNA isolation methods are complex, time consuming and require technical expertise. These limitations were overcome using the DNA isolation kits which, however significantly add to the research costs. Hence the present study was aimed to develop a high throughput, rapid and inexpensive method of PCR ready DNA template preparation from plant materials. METHODS: Concentration of SDS in lysis buffer, amount of starting material, period and temperature for lysis were optimized for obtaining PCR ready templates from plant materials. The method was tested using RAPD and ITS specific primers for different plant species like rice, wheat, mustard, pea, soybean, pigeonpea, tomato, maize, march lilly, bougainvillea, Indian blanket flower, nerium, petunia, purple pirouette petunia, moses-in-the-cradle, golden cane palm, duranta, periwinkle, chrysanthemum and two xerophytes viz. Dipterygium glaucum and Crotaleria burhia. SSR markers RM18398 and RM26108 showed successful amplification in rice varieties Improved Pusa Basmati 1 and KS Dev 12. The effectiveness of the method was tested using fresh as well as 1 year old tissues. The storability of the lysate was also tested. RESULTS: In this report, we developed a novel method called rapid high throughput template preparation (rHTTP) method to prepare PCR ready DNA templates. Most striking feature of this technique is that it can be done anywhere where water can be boiled by any means. Using rHTTP method, PCR ready templates can be prepared in just 10 min. Robust and reproducible amplification for all the test plants were recorded with RAPD, plant ITS primers and SSR markers following this method. rHTTP methods works well for both fresh as well as old plant tissues. The lysates had a shelf life of 1 month when stored at 4 °C and 3 days when stored at room temperature. CONCLUSIONS: rHTTP method has several advantages over the other protocols like ease of execution, no requirement of tissue grinding/liquid nitrogen/hazardous chemicals and above all, equally effective for both fresh and old samples. Using this method, costs per prep comes down ~ 10-50 times as compared to most commercial kits. This method can be used for on-field experiments like molecular diagnostics, varietal identification etc.

3D QSAR studies on protein tyrosine phosphatase 1B inhibitors: comparison of the quality and predictivity among 3D QSAR models obtained from different conformer-based alignments.

A set of 65 flexible peptidomimetic competitive inhibitors (52 in the training set and 13 in the test set) of protein tyrosine phosphatase 1B (PTP1B) has been used to compare the quality and predictive power of 3D quantitative structure-activity relationship (QSAR) comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models for the three most commonly used conformer-based alignments, namely, cocrystallized conformer-based alignment (CCBA), docked conformer-based alignment (DCBA), and global minima energy conformer-based alignment (GMCBA). These three conformers of 5-[(2S)-2-({(2S)-2-[(tert-butoxycarbonyl)amino]-3-phenylpropanoyl}amino)3-oxo-3-pentylamino)propyl]-2-(carboxymethoxy)benzoic acid (compound number 66) were obtained from the X-ray structure of its cocrystallized complex with PTP1B (PDB ID: 1JF7), its docking studies, and its global minima by simulated annealing. Among the 3D QSAR models developed using the above three alignments, the CCBA provided the optimal predictive CoMFA model for the training set with cross-validated r2 (q2)=0.708, non-cross-validated r2=0.902, standard error of estimate (s)=0.165, and F=202.553 and the optimal CoMSIA model with q2=0.440, r2=0.799, s=0.192, and F=117.782. These models also showed the best test set prediction for the 13 compounds with predictive r2 values of 0.706 and 0.683, respectively. Though the QSAR models derived using the other two alignments also produced statistically acceptable models in the order DCBA>GMCBA in terms of the values of q2, r2, and predictive r2, they were inferior to the corresponding models derived using CCBA. Thus, the order of preference for the alignment selection for 3D QSAR model development may be CCBA>DCBA>GMCBA, and the information obtained from the CoMFA and CoMSIA contour maps may be useful in designing specific PTP1B inhibitors.