Insight Into the Molecular Mechanisms Underpinning the Mycoremediation of Multiple Metals by Proteomic Technique.

We investigated the fungus Aspergillus fumigatus PD-18 responses when subjected to the multimetal combination (Total Cr, Cd2+, Cu2+, Ni2+, Pb2+, and Zn2+) in synthetic composite media. To understand how multimetal stress impacts fungal cells at the molecular level, the cellular response of A. fumigatus PD-18 to 30 mg/L multimetal stress (5 mg/L of each heavy metal) was determined by proteomics. The comparative fungal proteomics displayed the remarkable inherent intracellular and extracellular mechanism of metal resistance and tolerance potential of A. fumigatus PD-18. This study reported 2,238 proteins of which 434 proteins were exclusively expressed in multimetal extracts. The most predominant functional class expressed was for cellular processing and signaling. The type of proteins and the number of proteins that were upregulated due to various stress tolerance mechanisms were post-translational modification, protein turnover, and chaperones (42); translation, ribosomal structure, and biogenesis (60); and intracellular trafficking, secretion, and vesicular transport (18). In addition, free radical scavenging antioxidant proteins, such as superoxide dismutase, were upregulated upto 3.45-fold and transporter systems, such as protein transport (SEC31), upto 3.31-fold to combat the oxidative stress caused by the multiple metals. Also, protein-protein interaction network analysis revealed that cytochrome c oxidase and 60S ribosomal protein played key roles to detoxify the multimetal. To the best of our knowledge, this study of A. fumigatus PD-18 provides valuable insights toward the growing research in comprehending the metal microbe interactions in the presence of multimetal. This will facilitate in development of novel molecular markers for contaminant bioremediation.

Assessment of Drain Water Used for Irrigation in the Delhi Region.

BACKGROUND: Industries such as electroplating, mining and battery production are major sources of heavy metal-rich waste entering nearby water bodies. Irrigation with heavy metal contaminated water can deteriorate soil quality as well as agricultural produce and have further toxic effects on human health. OBJECTIVES: The objective of the present study was to estimate the concentration of hazardous heavy metals such as chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn) and lead (Pb), as well as physico-chemical variables (pH, electrical conductivity, total dissolved solids, chemical oxygen demand and dissolved oxygen) at sampling locations along the Najafgarh and Loha mandi drains in Delhi, National Capital Region, India. METHODS: The present study evaluated the quality of wastewater from the Najafgarh and Loha mandi drains, which are used for irrigational purposes in the Delhi region. Drain water quality was monitored for a period of 2 years for physico-chemical variables (pH, chemical oxygen demand, electrical conductivity and dissolved oxygen) as well as heavy metal concentrations (Cr, Cu, Cd, Zn, Ni and Pb). The two-year monitoring period (July 2012-March 2014) was chosen to represent three seasons: pre-monsoon, monsoon, and post-monsoon. RESULTS: Varied concentrations of multiple heavy metals were found due to the extensive discharge of untreated industrial effluents into the drain water. Punjabi Bagh of Najafgarh drain was the most contaminated sampling site with the maximum concentration of Zn (12.040 ± 0.361 mg L-1), followed by Cr (2.436 ± 0.073mg L-1) and Cu (2.617 ± 0.078 mg L-1). CONCLUSIONS: Consumption of heavy metal-contaminated agricultural products can cause deleterious human health effects, leading to further health problems. The presence of multi-heavy metal ions above the Food and Agriculture Organization of the United Nations (FAO) permissible limits indicated that drain water was not suitable for irrigational purposes, and adequate measures are required to remove the heavy metal load from drain water. COMPETING INTERESTS: The authors declare no competing financial interests.

Mechanistic insight to mycoremediation potential of a metal resistant fungal strain for removal of hazardous metals from multimetal pesticide matrix.

Fungi have an exceptional capability to flourish in presence of heavy metals and pesticide. However, the mechanism of bioremediation of pesticide (lindane) and multimetal [mixture of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn)] by a fungus is little understood. In the present study, Aspergillus fumigatus, a filamentous fungus was found to accumulate heavy metals in the order [Zn(98%)>Pb(95%)>Cd(63%)>Cr(62%)>Ni(46%)>Cu(37%)] from a cocktail of 30 mg L-1 multimetal and lindane (30 mg L-1) in a composite media amended with 1% glucose. Particularly, Pb and Zn uptake was enhanced in presence of lindane. Remarkably, lindane was degraded to 1.92 ± 0.01 mg L-1 in 72 h which is below the permissible limit value (2.0 mg L-1) for the discharge of lindane into the aquatic bodies as prescribed by European Community legislation. The utilization of lindane as a cometabolite from the complex environment was evident by the phenomenal growth of the fungal pellet biomass (5.89 ± 0.03 g L-1) at 72 h with cube root growth constant of fungus (0.0211 g1/3 L-1/3 h-1) compared to the biomasses obtained in case of the biotic control as well as in presence of multimetal complex without lindane. The different analytical techniques revealed the various stress coping strategies adopted by A. fumigatus for multimetal uptake in the simultaneous presence of multimetal and pesticide. From the Transmission electron microscope coupled energy dispersive X-ray analysis (TEM-EDAX) results, uptake of the metals Cd, Cu and Pb in the cytoplasmic membrane and the accumulation of the metals Cr, Ni and Zn in the cytoplasm of the fungus were deduced. Fourier-transform infrared spectroscopy (FTIR) revealed involvement of carboxyl/amide group of fungal cell wall in metal chelation. Thus A. fumigatus exhibited biosorption and bioaccumulation as the mechanisms involved in detoxification of multimetals.

Comparative performance evaluation of multi-metal resistant fungal strains for simultaneous removal of multiple hazardous metals.

In the present study, five fungal strains viz., Aspergillus terreus AML02, Paecilomyces fumosoroseus 4099, Beauveria bassiana 4580, Aspergillus terreus PD-17, Aspergillus fumigatus PD-18, were screened for simultaneous multimetal removal. Highest metal tolerance index for each individual metal viz., Cd, Cr, Cu, Ni, Pb and Zn (500mg/L) was recorded for A. fumigatus for the metals (Cd, 0.72; Cu, 0.72; Pb, 1.02; Zn, 0.94) followed by B. bassiana for the metals (Cd, 0.56; Cu, 0.14; Ni, 0.29; Zn, 0.85). Next, the strains were exposed to multiple metal mixture (Cd, Cr, Cu, Ni, Pb and Zn) of various concentrations (6, 12, 18, 30mg/L). Compared to other strains, B. bassiana and A. fumigatus had higher cube root growth (k) constants indicating their better adaptability to multi metal stress. After 72h, multimetal accumulation potential of B. bassiana (26.94±0.07mg/L) and A. fumigatus (27.59±0.09mg/L) were higher than the other strains at initial multimetal concentration of 30mg/L. However, considering the post treatment concentrations of individual metals in multimetal mixture (at all the tested concentrations), A. fumigatus demonstrated exceptional performance and could bring down the concentrations of Cd, Cu, Ni, Pb and Zn below the threshold level for irrigation prescribed by Food and Agriculture Organization (FAO).

Multiple heavy metal removal using an entomopathogenic fungi Beauveria bassiana.

Towards the development of a potential remediation technology for multiple heavy metals [Zn(II), Cu(II), Cd(II), Cr(VI) and Ni(II)] from contaminated water, present study examined the growth kinetics and heavy metal removal ability of Beauveria bassiana in individual and multi metals. The specific growth rate of B. bassiana varied from 0.025h(-1) to 0.039h(-1) in presence of individual/multi heavy metals. FTIR analysis indicated the involvement of different surface functional groups in biosorption of different metals, while cellular changes in fungus was reflected by various microscopic (SEM, AFM and TEM) analysis. TEM studies proved removal of heavy metals via sorption and accumulation processes, whereas AFM studies revealed increase in cell surface roughness in fungal cells exposed to heavy metals. Present study delivers first report on the mechanism of bioremediation of heavy metals when present individually as well as multi metal mixture by entomopathogenic fungi.

Assessment of Yamuna and associated drains used for irrigation in rural and peri-urban settings of Delhi NCR.

The present study assessed the quality of Yamuna River and the Najafgarh drain water for irrigational purposes in the Delhi region in terms of spatial variations in the physicochemical characteristics as well as heavy metal concentrations. The monitoring was done for the period July 2012-August 2013 representing pre-monsoon, monsoon, and post-monsoon sessions and considering six physicochemical parameters. Heavy metals such as cadmium, chromium, copper, nickel, zinc, and lead have been found in the river due to rampant discharge of industrial effluents into the river. The mean metal concentrations in the 15 sampling sites were in the range of (mg L(-1)) 0.02-0.64 (Cu), 0-0.42 (Cr), 0.13-2.22(Zn), 0.03-0.27 (Pb), 0-0.07 (Cd), and 0.01-0.13 (Ni). Multivariate statistics (PCA and HCA) were used to identify the possible sources of metal contamination and to examine the spatial changes in the Yamuna River as well as in the Najafgarh drain. This study reveals the occurrence of mean Cd concentration above the safe limit at Palla, Christian Ashram and Jagatpur of the Yamuna river while Punjabi Bagh of the Najafgarh drain necessitate treatment in terms of heavy metals such as Cd, Cu, Cr, Ni, Pb, and Zn before it could be rendered useful for irrigation.