Heavy metals, such as cobalt, copper, manganese, molybdenum, and zinc, are essential in trace amounts for growth by plants and other living organisms. However, in excessive amounts these heavy metals have deleterious effects. Like other organisms, plants possess a variety of detoxification mechanisms to counter the harmful effects of heavy metals. These include the restriction of heavy metals by mycorrhizal association, binding with plant cell wall and root excretions, metal efflux from the plasma membrane, metal chelation by phytochelatins and metallothioneins, and compartmentalization within the vacuole. Phytoremediation is an emerging technology that uses plants and their associated rhizospheric microorganisms to remove pollutants from contaminated sites. This technology is inexpensive, efficient, and ecofriendly. This review focuses on potential cellular and molecular adaptations by plants that are necessary to tolerate heavy metal stress.

The bacterium MNU16 was isolated from contaminated soils of coal mine and subsequently screened for different plant growth promotion (PGP) activities. The isolate was further identified by 16S rRNA sequencing as Bacillus subtilis MNU16 with IAA concentration (56.95±0.436µg/ml), siderophore unit (9.73±2.05%), phosphate solubilization (285.13±1.05µg/ml) and ACC deaminase activity (116±0.019 µmoles α-ketobutyrate /mg/24 h). Further, to evaluate the metal resistance profile of bacterium, the isolate was screened for multi-metal resistance (viz. 900 mg/L for Cr, 600 mg/L for As, 700 mg/L for Ni respectively and 300 mg/L for Hg). Additionally, the resistance pattern of Bacillus subtilis MNU16 against Cr(VI) (from 50-300 mg/L) treatments were evaluated. An enriched population was observed at 0-200 mg/L Cr(VI) concentration while slight reduction were shown at 250 and 300 mg/L Cr(VI). Further, the chromium reduction ability at 50 mg/L of Cr(VI) shows that the strain Bacillus subtilis MNU16 reduced 75% of Cr(VI) to 13.23 mg/L within 72 hours. Further, the chromium reduction ability at 50 mg/L of Cr(VI) highlighted that the bacterium Bacillus subtilis MNU16 reduced 75% of Cr(VI) to 13.23 mg/L within 72 hours. Transmission electron microscopy study was also performed and it was observed that the cells were able to accumulates Cr(VI) and EDP localization in cells was also observed which shows the reduction of Cr(VI) to Cr(III). The data of fluorescence microscopy and flow cytometry (FCM) when subjected to Cr(VI) treatments (50 mg/L to 300 mg/L) for 12 h of incubation showed the similar pattern and clearly revealed that, less toxic effect of hexavalent chromium was observed till 200 mg/L Cr(VI) concentration, however the toxicity affects more at 300 mg/L Cr(VI). Thus the present study suggests that due to the plant growth promoting potential of Bacillus subtilis MNU16 and its resistance efficacy at different level of Cr(VI) it will go a long way in developing an effective bioremediation approach for Cr(VI) contaminated soils.

Liposomes, the vesicles of phospholipid bilayer, can encapsulate both hydrophilic and lipophilic drugs and protect them from degradation. Liposomes have been extensively studied and continue to create intense interest in research since their discovery in the mid-1960s. Since then, liposomes have been considered to be the most successful nanocarriers for drug deliver and have made their way to the market. Currently, a number of liposomal formulations are on the marker for cancer treatment and many more are in pipe line. This review discusses about the liposome components, methods of preparation, drug encapsulation mechanism and the potential therapeutic applications of liposomes in cancer therapy.