Ecosystem Protection through Myco-Remediation of Chromium and Arsenic.

The current study emphasizes fungi as an important tool against heavy metals and how isolated fungal species can be used to create a successful strategy for the bioremediation of chromium and arsenic-contaminated sites/soils. Globally, heavy metal pollution is a serious issue. In the current investigation, contaminated sites were chosen, and samples could be taken from various localities of Hisar (29.1492° N, 75.7217° E) and Panipat (29.3909° N, 76.9635° E), India. A total of 19 fungal isolates were obtained from the collected samples through the enrichment culture technique using PDA media supplemented with Cr as chromic chloride hexahydrate (50 mg/L) and As as sodium arsenate (10 mg/L) and the potential of fungal isolates to be used for the removal of heavy metals was examined. The isolates were screened for minimum inhibitory concentrations (MIC) exhibiting tolerance capabilities, and the four best isolates C1, C3, A2, and A6 with the highest MICs (>5000 mg/L), were chosen for further investigations. To use the chosen isolates in the remediation of heavy metals (Cr and As), the culture conditions were optimized. The fungal isolates C1 and C3 estimated the highest removal of 58.60% and 57.00% at 50 mg/L chromium concentration, while the isolates A6 and A2 recorded the highest removal efficiency of 80% and 56% at 10 mg/L arsenic concentration under optimal conditions. Finally, the chosen fungal isolates C1 and A6 were molecularly identified as Aspergillus tamarii and Aspergillus ustus, respectively.

Studies on salinization in Haryana soils on free-living nitrogen-fixing bacterial populations and their activity.

A total of 26 soil samples from saline soils of Haryana were collected. Based on their electrical conductivity (EC) values, which varied from 1.04 to 21.00 dS m(-1), the soils were categorized into non-saline soils (EC 0-2 dS m(-1)), weakly saline soils (EC 2-4 dS m(-1)), saline soils (EC 4-8 dS m(-1)), strongly saline soils (EC 8-16 dS m(-1)), and very strongly saline soils (EC >16 dS m(-1)). The pH values of these soil samples ranged from 6.03 to 8.62, while organic C, total N, and available P were in the range of 0.06-0.94%, 0.07-0.15%, and 0.11-0.29 µg g(-1) soil, respectively. As a measure of the impact of salinity on free-living N(2) fixers and their activity, the total bacterial populations on four media (Jensen's nitrogen-free medium, malate medium, Burk's medium, and soil extract agar medium) decreased from 6.12 to 3.70 log CFU g(-1) soil with increasing salinity level. PCR amplification of the nifH region of the DNA from 234 selected morphotypes from all the media showed the presence of nifH in 71 isolates. Out of these, 37% of the isolates were obtained using Jensen's medium; 35, 28, and 21% of the isolates were obtained using soil extract medium, Burk's medium, and malate medium, respectively. The majority of the free-living N(2) fixers (67%) were Gram negative. Apart from the acetylene reduction assay (ARA) activity in these isolates, other beneficial traits like ammonia excretion and indole acetic acid (IAA) production were also present. A decreasing trend in the activities was observed with increasing salinity levels. Isolates JN6, BP8, and MJ4 showed the highest ARA activity, ammonia excretion, and IAA production. The performance of isolates like BNC2 with good ARA activity, ammonia excretion, and IAA production and isolated from a very strongly saline soil should be further evaluated under high-saline conditions.

Gordonia sp.: a salt tolerant bacterial inoculant for growth promotion of pearl millet under saline soil conditions.

In the resent study, a diazotrophic bacterial isolate JPA2 having the ability to tolerate salinity (6 % NaCl) and plant growth-promoting features was isolated from rhizospheric soil of weed Chenopodium murale growing in saline soil of Pindara (EC 11.47 dS m-1), district Jind (Haryana). The nitrogen fixing ability of the isolate was confirmed by nifH gene amplification and acetylene reduction assay (38.9 nmol ethylene h-1 mg-1 protein). The potential of strain JPA2 to promote growth of pearl millet was investigated by inoculation experiment which showed significant increase in plant height (51.1, 39.9 and 28.8 %) and dry weight (55.9, 36.4 and 35.5 %) over uninoculated control plants at EC 0, 6, 8 dS m-1, respectively. The strain JPA2 was Gram +ve and identified as Gordonia sp. on the basis of partial 16S rRNA gene sequencing and biochemical characterization. It is concluded that salt tolerant diazotrophic Gordonia sp. can be considered as a beneficial microbe for agriculture in saline soils.