In vitro Sequestration of Molecular and Mass Spectra Characterized Metallophilic Cadmium Tolerant Bacteria for Sustainable Agriculture.

Due to industrialization, the contamination of toxic metals in soils is currently one of the major concerns to scientists worldwide. The presence of high concentrations of heavy metals including cadmium in the environment is mainly attributed to human activities. Being a highly toxic metal, cadmium can enter plant cell transporters usually used for the uptake of essential cations, such as iron, calcium, and zinc. This study deals with the appraisement of response and tolerance shown by various bacteria in varied cadmium concentrations (100-1,000 ppm). The optical density (OD) of the isolates was measured to determine the minimum inhibitory concentration (MIC) of cadmium. Isolated bacteria have been identified using 16S rRNA gene sequence and Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Among the 72 isolates, 07 (Bacillus pumilus, Enterobacter kobei, Klebsiella pneumonia, Pseudomonas mandelii, Pseudomonas putida, Pseudomonas avellanae, and Staphylococcus equorum), isolates had efficacy for cadmium tolerance and showed sequestration potential at varying MIC. Furthermore, K. pneumonia was observed to have the highest (900 ppm) tolerance for cadmium and the lowest (600 ppm) was shown by E. kobei. Besides, K. pneumonia showed the highest (75.2%) sequestration potential while the least (52.4%) potential was observed for P. putida. These cadmium tolerant species can be implemented in contaminated environments for detoxification and elimination of cadmium from these agricultural fields. Graphical Abstract.

Ceratophyllum demersum-An accretion biotool for heavy metal remediation.

Freshwater habitats are under serious threat due to the diverse pressures of development and restoration of these ecosystems is an important challenge in the present era. With a number of scientifically advanced methods available for restoration of these systems, phytoremediation finds its unique space as an ecologically sustainable technique. In this paper, a case study of Certophyllum demersum as a tool of heavy metal remediation in Dal lake, a natural freshwater system in Kashmir, India is presented. At all concentrations (2 ppm, 4 ppm, 6 ppm) the metal accumulation efficiency of C. demersum is of the order of Co2+ > Cd2+ > Mn2+ followed by other metals. The carbohydrate- protein plot reveals positive correlation (0.696) with the heavy metal uptake while the lipid-protein plot overall shows a weak correlation (0.296) and the carbohydrate-lipid plot shows an insignificant correlation (0.019). The results of the present study revealed attenuation of protein levels at low doses which lowered with increased heavy metal concentrations. Further, the overall lipid and carbohydrate content of the cultured C. demersum displayed a general decline with a rise in the concentration of heavy metals The overall study indicates the efficiency of C. demersum to adapt in polluted conditions and its potential to remove heavy metals for sustainable restoration of the degraded aquatic systems.

Molecular characterization of lipase from a psychrotrophic bacterium Pseudomonas sp. CRBC14.

Lipases from Pseudomonas species are particularly useful due to their broader biocatalytic applications and temperature activity. In this study, we amplified the gene encoding wild-type cold-active lipase from the genome of psychrotrophic bacterium isolated from the Himalayan glacier. The isolated CRBC14 strain was identified as Pseudomonas sp. based on the 16S rRNA gene sequence. Lipase activity was determined by observing the hydrolysis zone on nutrient agar containing tributyrin (1%, v/v). The sequence analysis of cold-active lipase revealed a protein of 611 amino acids with a calculated molecular mass of 63.71 kDa. The three-dimensional structure of this lipase was generated through template-supported modeling. Distinct techniques stamped the model quality, following which the binding free energies of tributyrin and oleic acid in the complex state with this enzymatic protein were predicted through molecular mechanics generalized born surface area (MMGBSA). A relative comparison of binding free energy values of these substrates indicated tributyrin's comparatively higher binding propensity towards the lipase. Using molecular docking, we evaluated the binding activity of cold-active lipase against tributyrin and oleic acid. Our docking analysis revealed that the lipase had a higher affinity for tributyrin than oleic acid, as evidenced by our measurement of the hydrolysis zone on two media plates. This study will help to understand the bacterial diversity of unexplored Himalayan glaciers and the possible application of their cold-adapted enzymes.

MALDI-TOF-MS and 16S rRNA characterization of lead tolerant metallophile bacteria isolated from saffron soils of Kashmir for their sequestration potential.

Toxic metal contamination in soils due industrialization is nowadays a concern to the scientists worldwide. The current study deals with the evaluation of response and tolerance by isolated metallophilic bacteria in different lead concentrations (100 ppm to 1000 ppm). By taking optical densities of the isolates, the minimum inhibitory concentration (MIC) of Pb2+ were determined.16S rRNA and MALDI-TOF MS were used for the identification of the bacteria. Total of 37 isolates were observed, among them 04 (Staphylococcus equorum, Staphylococcus warneri, Bacillus safensis and Bacillus thuringiensis), isolated were detected having efficacy of Pb2+tolerance and sequestration at varying MIC. Furthermore, B. thuringiensis was observed to have highest (900 ppm) tolerance for lead and lowest (500 ppm) for Staphylococcus warneri. Moreover, the highest (65.3%) sequestration potential has been observed for B. thuringiensis and least (52.8%) for S. warneri. The tolerance and sequestration potential properties of these isolated species can be utilised to exterminate heavy metals and reduce their toxicity from the contaminated environment.