Journal of Genetic Engineering and Biotechnology最新文献

Marine environments are substantially untapped source for the isolation of bacteria with the capacity to produce various extracellular hydrolytic enzymes, which have important ecological roles and promising biotechnological applications. Hydrolases constitute a class of enzymes widely distributed in nature from bacteria to higher eukaryotes. Marine microbial communities are highly diverse and have evolved during extended evolutionary processes of physiological adaptations under the influence of a variety of ecological conditions and selection pressures. A number of marine hydrolases have been described, including amylases, lipases and proteases, which are being used extensively for biotechnological applications. The present study was carried out to isolate marine bacteria from continental slope sediments of the eastern Arabian Sea and explore their biotechnological potential. Among the 119 isolates screened, producers of amylases (15%), caseinases (40%), cellulases (40%), gelatinases (60%), lipases (26%), ligninases (33%), phytase (11%) and Malachite Green dye degraders (16%) were detected. Phylogenetic analysis based on 16S rRNA gene sequencing showed that predominant marine sediment bacteria possessing more than four enzymatic activities belonged to the phyla Firmicutes and Proteobacteria, was assigned to the genera Bacillus, Planococcus, Staphylococcus, Chryseomicrobium, Exiguobacterium and Halomonas. Biodegradation of the dye Malachite Green using the liquid decolorization assay showed that both the individual cultures (Bacillus vietnamensis, Planococcus maritimus and Bacillus pumilus) and their consortium were able to decolorize more than 70% of dye within 24 h of incubation. This is the first report on diversity and extracellular hydrolytic enzymatic activities and bioremediation properties of bacteria from continental slope sediment of eastern Arabian Sea.

This experiment assessed the biochemical changes in fenugreek plants exposed to gamma radiation. Two pot experiments were carried out during two growing seasons of 2015 and 2016. Seeds were subjected to five doses of gamma irradiation (25, 50, 100, 200 and 400 Gy) and were immediately planted into soil pots in a greenhouse. The experimental analysis was performed in M₁ and M₂ generations. Significant differences between irradiated and control plants were detected for most studied characters in M₁ and M₂ generations. It was demonstrated that low doses of gamma irradiation led to gradually increases in growth, yield characters, leaf soluble protein concomitantly with increases in the contents of phenolic and flavonoids compounds particularly at 100 Gy. These changes were accompanied by a substantial increase in ascorbic acid, α-tocopherol and retinol contents. Proline content was increased under all doses of gamma rays in M₁ generation and the highest amount of proline was obtained at 200 Gy with visible decrease in M₂ generation under the same dose. Meanwhile, the highest dose of gamma radiation (400 Gy) decreased all the studied parameters in both mutagenic generations as compared with control plants. In addition, gamma irradiation doses induced changes in DNA profile on using five primers and caused the appearance and disappearance of DNA polymorphic bands with variation in their intensity. These findings confirm the effectiveness of relatively low doses of gamma rays on improving the physiological and biochemical criteria of fenugreek plants.

The present study was intended to optimize the quorum sensing inhibitory action of Solanum torvum root extract against Chromobacterium violaceum. Factors such as bacterial density, frequency of administration and concentration of extract were analysed. Plant samples were collected from Thrissur District, Kerala, India. Response surface modelling of factors by Box-Behnken approach was employed for optimizing quorum quenching activity of extract. The adequacy of mathematical model was verified by ANOVA and Cook’s distance table. Results revealed that quorum quenching property of Solanum torvum root extract is highly influenced by variables studied whereas maximum activity was found during administration of 300 µg/ml extract thrice in a day. It was also understood that extract does not possess any bactericidal activity wherein it only silence its quorum sensing mediated functions. This observations can be further used in quorum quenching studies.

Lipases from psychrotrophic fungal isolates BPF4 and BPF6 identified as Penicilium canesense and Pseudogymnoascus roseus respectively were characterized for their compatibility towards laundry detergent. BPF4 and BPF6 lipases showed maximum activity at pH 11 and 9 respectively and at 40 °C. The residual activities at 20 °C and 4 °C of BPF4 lipase were 35% and 20% and of BPF6 lipase were 70% and 20 °C respectively. Both the enzymes were stable at 4 °C, 20 °C and 40 °C for 2 h losing at the most 20% of activities. Both the enzymes were metalloenzymes with activity enhancement by nearly threefold by Ca²⁺. Contrary to BPF6 lipase, BPF4 enzyme was not stimulated by EDTA nor inhibited, rather stimulated by SDS and Triton X-100 by 125% and 330% respectively. Both the lipases showed minor to moderate inhibition by NaClO₃ and H₂O₂, and exhibited nearly 90% residual activity after 1 h of incubation in selected detergent brands thus indicating potential for their inclusion in detergent formulation thereby facilitating cold-washing as a step towards mitigation of climate change.

Bacteria communicate within a system by means of a density dependent mechanism known as quorum sensing which regulate the metabolic and behavioral activities of a bacterial community. This sort of interaction occurs through a dialect of chemical signals called as autoinducers synthesized by bacteria. Bacterial quorum sensing occurs through various complex pathways depending upon specious diversity. Therefore the cognizance of quorum sensing mechanism will enable the regulation and thereby constrain bacterial communication. Inhibition strategies of quorum sensing are collectively called as quorum quenching; through which bacteria are incapacitated of its interaction with each other. Many virulence mechanism such as sporulation, biofilm formation, toxin production can be blocked by quorum quenching. Usually quorum quenching mechanisms can be broadly classified into enzymatic methods and non-enzymatic methods. Substantial understanding of bacterial communication and its inhibition enhances the development of novel antibacterial therapeutic drugs. In this review we have discussed the types and mechanisms of quorum sensing and various methods to inhibit and regulate density dependent bacterial communication.

Most autoimmune disease are driven by a dysfunction in T and B cells, but B cells are still an interesting area of research, perturbations in their development are implicated in autoimmune diseases. B cell differentiating factor (BCDF) plays a part in the differentiation of B cells. The aim was To assess the levels of BCDF, IgM and IgG in SLE patients and whether they have any peculiarity in the clinical context of SLE. Thirty six patients with SLE and 24 healthy volunteers as control were enrolled in the study. BCDF was measured using Sandwich ELISA, total human IgM and IgG were measured by calorimetric methods. The mean concentrations of BCDF and IgM were significantly higher in patients with SLE as compared with controls (P < 0.001 and P < 0.0001 respectively). No significant difference was observed as regard IgG. We observed positive correlation between BCDF and IgM (r = 0.281, P = 0.03), and between IgG and IgM, duration of the disease (r = 0.468, P = 0.004, r = 0.337, P = 0.008 respectively). Moreover we observed lower IgM level in patients with discoid lesion (P = 0.009) and lower IgG level in those with hematologic manifestations (P = 0.02). ROC analysis revealed area under curve (AUC) 0.861 for BCDF and 0.902 for IgM, they can delineate SLE from controls at a cut-off value of 98.5 pg/ml, and 18 mg/dl IgM respectively.

Conclusion

BCDF and IgM are increased in SLE patients and are promissing diagnostic markers for SLE.

Heterologous expression of Integral Membrane Proteins (IMPs) is reported to be toxic to the host system in many studies. Even though there are reports on various concerns like transformation efficiency, growth properties, protein toxicity, inefficient expression and protein degradation in IMP overexpression, no studies so far addressed these issues in a comprehensive way. In the present study, two transmembrane proteins of the pathogen Leptospira interrogans, namely Signal peptidase (SP), and Leptospira Endostatin like A (Len-A) were taken along with a cytosolic protein Hydrolase (HYD) to assess the differences in transformation efficiency, protein toxicity, and protein stability when over expressed in Escherichia coli (E. coli). Bioinformatics analysis to predict the transmembrane localization indicated that both SP and Len are targeted to the membrane. The three proteins were expressed in full length in the E. coli expression strain, BL 21 (DE3). Significant changes were observed for the strains transformed with IMP genes under the parameters analysed such as, the transformation efficiency, survival of colonies on IPTG-plate, culture growth kinetics and protein expression compared to the strain harbouring the cytosolic protein gene.