Högskolan i Skövde

Exposure to toxic metals alters host response and that leads to disease development. Studies have revealed the effects of metals on microbial physiology, however, the role of metal resistant bacteria on host response to metals is unclear. The hypothesis that xenobiotic interactions between gut microbes and arsenic influence the host physiology and toxicity was assessed in a Caenorhabditis elegans model. The arsenic-resistant Lysinibacillus sphaericus B1CDA was fed to C. elegans to determine the host responses to arsenic in comparison to Escherichia coli OP50 food. L. sphaericus diet extended C. elegans lifespan compared to E. coli diet, with an increased expression of genes involved in lifespan, stress response and immunity (hif-1, hsp-16.2, mtl-2, abf-2, clec-60), as well as reduced fat accumulation. Arsenic-exposed worms fed L. sphaericus also had a longer lifespan than those fed E. coli and had an increased expression of genes involved in cytoprotection, stress resistance (mtl-1, mtl-2) and oxidative stress response (cyp-35A2, isp-1, ctl-2, sod-1), together with a decreased accumulation of reactive oxygen species (ROS). In comparison with E. coli, L. sphaericus B1CDA diet increased C. elegans fitness while detoxifying arsenic induced ROS and extending lifespan.

Microbial technologies play an extremely crucial role in wastewater treatment. In the last few decades, the focus was on wastewater treatment; however, with the consumption of already finite resources, this focus has now shifted to wastewater remediation and recycling. The latest technologies are more robust at wastewater treatment and the recovery of useful compounds from the wastewaters. This chapter compiles the latest technologies in which microbial/bacterial biomass was used for wastewater treatment and remediation. This chapter also gives a special focus on remediation of wastewaters contaminated with heavy metals, describing the basic technologies as well as smart technologies. Emphasis is given to circular bioeconomy and how it can be implemented in wastewater treatment. A circular model incorporating key areas such as point source detection of pollutants, characterization of wastewaters, choice of the remedial technology, and type of treatment is explained in the chapter.

Air pollution is a serious health concern that affects many people across the globe. The major air pollutants are particulate matter, carbon oxides, nitrogen oxides, sulphur oxides, volatile organic compounds, polycyclic aromatics and free radicals which cause severe respiratory distress and infections. The existing air cleaning systems suffer from drawbacks of high cost and generation of secondary pollutants. A novel biological air filter “Biosmotrap” which is a laminate composite of sponge gourd and algae was developed. Biosmotrap placed in a carrier assembly on exhaust of vehicles, could remove carbon monoxide, nitric oxide, nitrogen dioxide, and fine particulate matter (PM2.5) from the vehicular emissions resulting in cleaner emissions. Biosmotrap decreased carbon monoxide from 1,423,992 μg/m3 to 76,756 μg/m3, nitric oxide from 71,128 μg/m3 to 9982 μg/m3, nitrogen dioxide from 565 μg/m3 to 188 μg/m3 and PM2.5 from 3200 μg/m3 to 60 μg/m3 from a polluting vehicle. Biosmotrap removed 60–80% of indoor pollutants from cigarette smoke and incense-stick smoke. Biosmotrap could protect the human cells from oxidative DNA damage induced by indoor air pollutants. Hibiscus rosa-sinensis plants exposed to air filtered through Biosmotrap were healthy as compared to the plants directly exposed to polluted air. Biosmotrap is an economic, efficient, eco-friendly filter that is superior to existing air filtration methods. 

This study characterizes different MTP1 (metal tolerance protein)/ZAT (zinc transporter) homologs involved in zinc (Zn) homeostasis in plants. BLAST analysis of AtMTP1 protein against 15 plant species showed 21 MTP1 homologs. These MTP1 protein homologs generally contain ~400 residues, six transmembrane helices and cation transmembrane transporter activity (GO:0008324), which can be utilized in predicting Zn uptake and tolerance mechanisms. These MTP1 genes having 1 exon are located on chromosomes 2, 7, and 14. Motifs contain conserved sequences of 41–50 residues belonging to the cation efflux family, which may help target binding sites and transcription factors. Further, AtMTP1 shows close similarities with Glycine max and Medicago trunculata. Interactome analysis suggests the association of AtMTP1 with cadmium/zinc-transporting ATPase and ZIP metal ion transporter. The AtMTP1 network is predominantly connected to cadmium/zinc-transporting ATPase (heavy metal ATPase 2, HMA2; heavy metal ATPase 3, HMA3; heavy metal ATPase 4, HMA4), cation efflux protein (MTP11), and metal tolerance protein C3 (AT4G58060). The Genevestigator predicts the high expression potential of AtMTP1 in the apical root during senescence, seedling, and bolting stages in an association with 11 co-expressed genes, mainly linked to estradiol toxicity and heat stress. Besides, AtMTP1 protein homologs possess conserved N-glyco motifs and physicochemical properties. The similarity and interactions of AtMTP1 gene with other genes suggest that Zn homeostasis in plants is associated with the regulation of different genes. These findings may advance our understanding to further develop plants capable of maintaining Zn homeostasis under adverse conditions. © 2021 Elsevier Inc.

Mercury (Hg) is toxic to plants, but the effect of glutathione in Hg alleviation was never studied in alfalfa, an important forage crop. In this study, Hg toxicity showed morphological retardation, chlorophyll reduction, and PSII inefficiency, which was restored due to GSH supplementation in alfalfa plants treated with Hg. Results showed a significant increase of Hg, but Fe and S concentrations substantially decreased in root and shoot accompanied by the downregulation of Fe (MsIRT1) and S (MsSultr1;2 and MsSultr1;3) transporters in roots of Hg-toxic alfalfa. However, GSH caused a significant decrease of Hg in the shoot, while the root Hg level substantially increased, accompanied by the restoration of Fe and S status, relative to Hg-stressed alfalfa. The subcellular analysis showed a substantial deposition of Hg in the root cell wall accompanied by the increased GSH and PC and the upregulation of MsPCS1 and MsGSH1 genes in roots. It suggests the involvement of GSH in triggering PC accumulation, causing excess Hg bound to the cell wall of the root, thereby reducing Hg translocation in alfalfa. Bioinformatics analysis showed that the MsPCS1 protein demonstrated one common conserved motif linked to the phytochelatin synthase domain (CL0125) with MtPCS1 and AtMCS1 homologs. These in silico analysis further confirmed the detoxification role of MsPCS1 induced by GSH in Hg-toxic alfalfa. Additionally, GSH induces GSH and GR activity to counteract oxidative injuries provoked by Hg-induced H2O2 and lipid peroxidation. These findings may provide valuable knowledge to popularize GSH-derived fertilizer or to develop Hg-free alfalfa or other forage plants. 

Polluted waters are an important reservoir for antibiotic resistance genes and multidrug-resistant bacteria. This report describes the microbial community, antibiotic resistance genes, and the genetic profile of extended spectrum β-lactamase strains isolated from rivers at, Pune, India. ESBL-producing bacteria isolated from diverse river water catchments running through Pune City were characterized for their antibiotic resistance. The microbial community and types of genes which confer antibiotic resistance were identified followed by the isolation of antibiotic-resistant bacteria on selective media and their genome analysis. Four representative isolates were sequenced using next generation sequencing for genomic analysis. They were identified as Pseudomonas aeruginosa, Escherichia coli, and two isolates were Enterobacter cloacae. The genes associated with the multidrug efflux pumps, such as tolC, macA, macB, adeL, and rosB, were detected in the isolates. As MacAB-TolC is an ABC type efflux pump responsible for conferring resistance in bacteria to several antibiotics, potential efflux pump inhibitors were identified by molecular docking. The homology model of their MacB protein with that from Escherichia coli K12 demonstrated structural changes in different motifs of MacB. Molecular docking of reported efflux pump inhibitors revealed the highest binding affinity of compound MC207-110 against MacB. It also details the potential efflux pump inhibitors that can serve as possible drug targets in drug development and discovery. 

Fresh vegetables are potential source of lactic acid bacteria (LAB). In the present study, LAB were isolated from the fresh vegetables from Pune region. Total 266 LAB were isolated from the edible parts of fresh vegetables viz. cauliflower, gherkins, cluster beans, fenugreek, cow pea, bitter gourd, french beans, tomato, ridged gourd, cucumber and bottle gourd. On phenotypic and molecular characterization predominant genera obtained were Lactobacillus, Enterococcus and Weissella. Twenty one isolates exhibited tolerance to bile salt, acidic pH and pancreatin. Cellular extracts of several isolates with ability to survive in artificial intestinal condition additionally showed antioxidant potential and cell free supernatants xhibited antibacterial potential against selected plant and human pathogens. Bacteriocin and bacteriocin like substances (BLS) substances secreted by these isolates can be used for food preservation.

Rhizobium spp. was isolated from root nodules of Pigeon pea (Cajanus cajan L.), Sweet pea (Lathyrus sativus L.), Chickpea (Cicer arietinum L.). The isolates ware rod shaped, aerobic, gram negative, motile and non-spore forming. Isolates were positive to Catalase, Citrate utilization, Urea hydrolysis, Congored, Nitrification, Oxidase, Triple sugar iron and MacConkey agar test. The isolates can ferment all nine sugars. Then, the isolates identified as Rhizobium spp. Depending on above results were subjected to 16S rRNA sequencing for further confirmation and identification. Surprisingly, theisolates were same strain or member of same cluster of Rhizobium and identified as Rhizobium sp.CCNWYC119 strain based on 16S rRNA sequence (98% similarity). Then, different parameters of soil quality enrichment and plant growth viz.plant height; weight of pods and seeds; number, fresh and dry weight of nodules were studied to test the efficacy of the isolate as biofertilizer. Here, inoculant of Rhizobium sp. isolated from Pigeon pea was used as biofertilizer. The results showed the significant increase of nodulation, enrichment of soil of rhizosphere, plant growth and yield for all three types of inoculated peas as compared with non-inoculated control peas indicating that the isolated strain could be used as a common efficient biofertilizer for Pigeon pea, Sweet pea and Chick pea. It was also found that the isolate grew optimally at temperature 28°C and pH 7.0.Moreover, the isolate was sensitive to the higher concentration of NaCl (>1%) and to antibiotics- Mecillinam, Ciprofloxacin,Cotrimoxazole, Pefloxacin, Ceftazidime and Tetracycline.

Arsenic (As) is a phytotoxic element causing health hazards. This work investigates whether and how silicon (Si) alleviates As toxicity in wheat. The addition of Si under As-stress significantly improved morphophysiological characteristics, total protein, and membrane stability compared to As-stressed plants, suggesting that Si does have critical roles in As detoxification in wheat. Analysis of arsenate reductase activity and phytosiderophore (PS) release reveals their no involvement in the Si-mediated alleviation of As in wheat. Furthermore, Si supplementation in As-stressed plants showed a significant increase of As in roots but not in shoots compared with the plants grown under As stress. Further, gene expression analysis of two chelating molecules, TaPCS1 (phytochelatin synthase) and TaMT1 (metallothionein synthase) showed significant induction due to Si application under As stress compared with As-stressed plants. It is consistent with the physiological observations and suggests that alleviation of As toxicity in rice might be associated with As sequestration in roots leading to reduced As translocation in shoots. Furthermore, increased catalase, peroxidase, and glutathione reductase activities in roots imply the active involvement of reactive oxygen species scavenging for protecting wheat plants from As-induced oxidative injury. The study provides mechanistic evidence on the beneficial effect of Si on As toxicity in wheat plants.

Food-based exposure to arsenic is a human carcinogen and can severely impact human health resulting in many cancerous diseases and various neurological and vascular disorders. This project is a part of our attempts to develop new varieties of crops for avoiding arsenic contaminated foods. For this purpose, we have previously identified four key genes, and molecular functions of two of these, AtACR2 and AtPCSl, have been studied based on both in silico and in vivo experiments. In the present study, a T-DNA tagged mutant, (SALK-143282C with mutation in AtACR2 gene) of Arabidopsis thaliana was studied for further verification of the function of AtACR2 gene. Semi-quantitative RT-PCR analyses revealed that this mutant exhibits a significantly reduced expression of the AtACR2 gene. When exposed to 100 μM of arsenate (AsV) for three weeks, the mutant plants accumulated arsenic approximately three times higher (778 μg/g d. wt.) than that observed in the control plants (235 μg/g d. wt.). In contrast, when the plants were exposed to 100 μM of arsenite (AsIII), no significant difference in arsenic accumulation was observed between the control and the mutant plants (535 μg/g d. wt. and 498 μg/g d. wt., respectively). Also, when arsenate and arsenite was measured separately either in shoots or roots, significant differences in accumulation of these substances were observed between the mutant and the control plants. These results suggest that AtACR2 gene is involved not only in accumulation of arsenic in plants, but also in conversion of arsenate to arsenite inside the plant cells. © 2017 Institute of Molecular Biology, Slovak Academy of Sciences.