Inoculation of heavy metal resistant bacteria alleviated heavy metal-induced oxidative stress biomarkers in spinach (Spinacia oleracea L.).

Most vegetable crops are severely affected by the uptake of heavy metals from the soil. Heavy metals in vegetable bodies generate reactive oxygen species (ROS) that unbalance the antioxidant defense system. This study was initiated to determine the physiological and biochemical characteristics of spinach plants grown on soil contaminated with heavy metals and responding to Bacillus cereus and Bacillus aerius were isolated from soil contaminated with heavy metals. Heavy metal contamination led to a significant reduction in seed germination, seedling biomass, protein, and total nitrogen content of spinach plants grown in contaminated soils compared to control soils. In contrast, a significant increase in the content of metallothioneins and antioxidant enzymes was observed. Plants inoculated with B. cereus and B. aerius significantly reduced the oxidative stress induced by heavy metals by improving seed germination (%), seedling growth, nitrogen, and protein content. The content of metallothioneins and the activities of antioxidant enzymes were reduced in spinach plants grown from seeds inoculated with bacterial strains. In addition, plants inoculated with, B. cereus and B. aerius showed greater stomata opening than plants grown on soil contaminated with heavy metals, whose stomata were almost closed. These results suggested that both bacterial strains enhanced plant growth by reducing oxidative stress caused by metals.

Multivariate geo-statistical perspective: evaluation of agricultural soil contaminated by industrial estate's effluents.

Present study was carried out to explore heavy metals pollution and potential ecological risk factors associated with agriculture soil irrigated with industrial effluents of Hayatabad industrial estate, Peshawar (HIEP) and Gadoon industrial estate, Sawabi (GIES) of Khyber-Pakhtunkhwa, Pakistan through multivariate geo-statistical tools. Diverse statistical tools like cluster analysis (HC) and principal component analysis (PCA), along with geo-statistical approaches were applied to highlight the geogenic and anthropogenic sources of pollution. The results indicated that concentration of heavy metals in target areas was significantly higher than control. Both soils had significant to moderate enrichment of heavy metals, while Gadoon soil had moderate to considerable ecological risk factor. The geo accumulation indices (Igeo) tendency for heavy metals in both target soil (Gadoon and Hayatabad) were the same. The Pb concentration of both target areas falls in the extremely severely polluted category because of the excessive presence of industries producing lead-containing products. Hence, this study indicated that the majority of toxic heavy metals contributed to soil pollution in the studied areas are coming from industrial and commercial activities.

Biosorption of heavy metals by Pseudomonas species isolated from sugar industry.

Heavy metal-resistant bacteria can be efficient bioremediators of metals and may provide an alternative or additional method to conventional methods of metal removal. In this study, 10 bacterial isolates were isolated from soil samples of a sugar industry, located at Peshawar, Pakistan. Morphological, physiological, and biochemical characteristics of these isolates were observed. Sequence analysis (16S ribosomal RNA) revealed that isolated strains were closely related to the species belonging to the genera Pseudomonas, Arthrobacter, Exiguobacterium, Citrobacter, and Enterobacter Bacterial isolates were resistant with a minimum inhibitory concentration (500-900 ppm) to lead ion (Pb(2+)), (500-600 ppm) nickel ion (Ni(2+)), (500-800 ppm) copper ion (Cu(2+)), and (600-800 ppm) chromium ion (Cr(3+)) in solid media. Furthermore, biosorption of metals proved considerable removal of heavy metals by isolated metal-resistant strains. Pseudomonas sp. reduced 37% (Pb(2+)), 32% (Ni(2+)), 29% (Cu(2+)), and 32% (Cr(3+)) and was thus found to be most effective, whereas Enterobacter sp. reduced 19% (Pb(2+)), 7% (Ni(2+)), 14% (Cu(2+)), and 21% (Cr(3+)) and was found to be least effective. While average reduction of Pb(2+), Ni(2+), Cu(2+), and Cr(3+) by Citrobacter sp. was found to be 24%, 18%, 23%, and 27%, respectively, among recognized species. This study revealed that Pseudomonas sp. may provide a new microbial community that can be used for enhanced remediation of contaminated environment.

Pb-induced changes in roots of two cultivated rice cultivars grown in lead-contaminated soil mediated by smoke.

Nowadays, public concerns regarding deleterious effect of lead (Pb) is on rise due to its abundance and toxic effect on plants and other living organisms. In plants, it has no noticeable biological importance but can cause various morphological, physiological, and biochemical malfunctions. To evaluate the remediating potential of plant-derived smoke (Cymbopogon jwarancusa), a pot culture experiment was designed to investigate the physiological, biochemical, metabolic, and antioxidant parameters of roots in lead (0 (control), 500, 1000, and 1500 ppm)-contaminated soil. Under dark condition, seeds were primed in smoke solution with two dilutions (1:500 and 1:1000) for 24 h. With an increasing concentration of Pb stress, fresh and dry weight and total nitrogen and protein contents decreased significantly while an increase was observed in smoke-treated seed. With increasing Pb stress level, metabolites (i.e., proline, total soluble sugar, total soluble protein, glycine betaine), and antioxidants (i.e., superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, malonyldialdehyde, and H2O2), contents of roots were increased in non-treated (without smoke treatment) samples, whereas comparatively, a low level of alteration in aforementioned metabolites and antioxidative parameters was observed in the seeds treated with smoke solution. These results suggest a positive role of smoke in alleviating lead-induced changes in roots of two cultivated cultivars of rice grown in Pb-contaminated soil.

Bacillus safensis with plant-derived smoke stimulates rice growth under saline conditions.

Salinity is a worldwide environmental problem of agricultural lands. Smoke and plant growth-promoting bacteria (PGPR) are individually used to improve plant growth, but the combined effects of these have not been studied yet under saline conditions. The combined effect of plant growth-promoting bacteria Bacillus safensis and plant-derived smoke Cymbopogon jwarancusa was studied under different salinity level as 50, 100, and 150 mM on rice (cv. Basmati-385). Smoke dilutions of C. jwarancusa (C-500 and C-1000) and bacterial culture of B. safensis were used to soak seeds for 10 h. It was observed that the salt concentration decreases the germination percentage, vegetative growth, ion contents (K+ and Ca2+), and photosynthetic pigments (Chl "a," Chl "b," and carotene) while an increase occurred in Na+, total soluble protein (TSP), proline, total soluble sugar, catalase (CAT), and peroxidase (POD) contents. The combined effect of B. safensis and smoke primed seeds increased the germination percentage, seedling growth, ion contents (K+, Ca2+), and photosynthetic pigments (Chl "a," Chl "b," carotene) and reduced the Na+ ion content, total soluble protein, proline content, total soluble sugar, CAT, and POD activity by lowering the drastic effect of salt stress. It was concluded that combined effect of smoke and PGPR is more effective than individual effect.

Drinking Water Quality Status and Contamination in Pakistan.

Due to alarming increase in population and rapid industrialization, drinking water quality is being deteriorated day by day in Pakistan. This review sums up the outcomes of various research studies conducted for drinking water quality status of different areas of Pakistan by taking into account the physicochemical properties of drinking water as well as the presence of various pathogenic microorganisms. About 20% of the whole population of Pakistan has access to safe drinking water. The remaining 80% of population is forced to use unsafe drinking water due to the scarcity of safe and healthy drinking water sources. The primary source of contamination is sewerage (fecal) which is extensively discharged into drinking water system supplies. Secondary source of pollution is the disposal of toxic chemicals from industrial effluents, pesticides, and fertilizers from agriculture sources into the water bodies. Anthropogenic activities cause waterborne diseases that constitute about 80% of all diseases and are responsible for 33% of deaths. This review highlights the drinking water quality, contamination sources, sanitation situation, and effects of unsafe drinking water on humans. There is immediate need to take protective measures and treatment technologies to overcome unhygienic condition of drinking water supplies in different areas of Pakistan.