Bioremoval of lead using Pennisetum purpureum augmented with Enterobacter cloacae-VITPASJ1: A pot culture approach

An insight on the plausible biological and non-biological detoxification of heavy metals in tannery waste: A comprehensive review

A key challenge for the tannery industries is the volume of tannery waste water (TWW) generated during the processing of leather, releasing various forms of toxic heavy metals resulting in uncontrolled discharge of tannery waste (TW) into the environment leading to pollution. The pollutants in TW includes heavy metals such as chromium (Cr), cadmium (Cd), lead (Pb) etc, when discharged above the permissible limit causes ill effects on humans. Therefore, several researchers have reported the application of biological and non-biological methods for the removal of pollutants in TW. This review provides insights on the global scenario of tannery industries and the harmful effects of heavy metal generated by tannery industry on micro and macroorganisms of the various ecological niches. It also provides information on the process, advantages and disadvantages of non-biological methods such as electrochemical oxidation, advanced oxidation processes, photon assisted catalytic remediation, adsorption and membrane technology. The various biological methods emphasised includes strategies such as constructed wetland, vermitechnology, phytoremediation, bioaugmentation, quorum sensing and biofilm in the remediation of heavy metals from tannery wastewater (TWW) with special emphasize on chromium.

Isolation and identification of a new Bacillus glycinifermentans strain from date palm rhizosphere and its effect on barley seeds under heavy metal stress

Soil contamination by heavy metals is one of the major problems that adversely decrease plant growth and biomass production. Inoculation with the plant growth-promoting rhizobacteria (PGPR) can attenuate the toxicity of heavy metals and enhancing the plant growth. In this study, we evaluated the potential of a novel extremotolerant strain (IS-2 T) isolated from date palm rhizosphere to improve barley seedling growth under heavy metal stress. The species-level identification was carried out using morphological and biochemical methods combined with whole genome sequencing. The bacterial strain was then used in vitro for inoculating Hordeum vulgare L. exposed to three different Cr, Zn, and Ni concentrations (0.5, 1, and 2 mM) in petri dishes and different morphological parameters were assessed. The strain was identified as Bacillus glycinifermentans species. This strain showed high tolerance to pH (6-11), salt stress (0.2-2 M), and heavy metals. Indeed, the minimum inhibitory concentrations at which bacterium was unable to grow were 4 mM for nickel, 3 mM for zinc, more than 8 mM for copper, and 40 mM for chromium, respectively. It was observed that inoculation of Hordeum vulgare L. under metal stress conditions with Bacillus glycinifermentans IS-2 T stain improved considerably the growth parameters. The capacity of the IS-2 T strain to withstand a range of abiotic stresses and improve barley seedling development under lab conditions makes it a promising candidate for use as a PGPR in zinc, nickel, copper, and chromium bioremediation.

Siderophores: an alternative bioremediation strategy?

Siderophores are small molecular weight iron scavengers that are mainly produced by bacteria, fungi, and plants. Recently, they have attracted increasing attention because of their potential role in environmental bioremediation. Although siderophores are generally considered to exhibit high specificity for iron, they have also been reported to bind to various metal and metalloid ions. This unique ability allows siderophores to solubilise and mobilise heavy metals and metalloids from soil, thereby facilitating their bioremediation. In addition, because of their redox nature, they can mediate the production of reactive oxygen species (ROS), and thus promote the biodegradation of organic contaminants. The aim of this review is to summarise the existing knowledge on the developed strategies of siderophore-assisted bioremediation of metals, metalloids, and organic contaminants. Additionally, this review also includes the biosynthesis and classification of microbial and plant siderophores.

Probiotic Characterization of Indigenous Kocuria flava Y4 Strain Isolated from Dioscorea villosa Leaves

This aim of the study was to isolate and screen potential probiotics from Dioscorea villosa leaves. The potential isolate Y4 was obtained from the Dioscorea villosa leaves, and its ability to grow in a medium containing high NaCl concentrations (2-10%) indicated its negative hemolytic activity. Furthermore, Y4 demonstrated inhibitory activity against human pathogens, such as Klebsiella pneumonia, Staphylococcus aureus, Citrobacter koseri, and Vibrio cholerae, as well as towards a plant pathogen isolate OR-2 (obtained from Citrus sinensis). Some biologically important functional groups of Y4 metabolites, such as sulfoxide; aliphatic ether; 1, 2, 3-trisubstituted, tertiary alcohol: vinyl ether; aromatic amine; carboxylic acid; nitro compound; alkene mono-substituted; and alcohol, were identified through FTIR analysis. The 16S rRNA sequencing and subsequent phylogenetic tree analysis indicated that Y4 and OR-2 are the closest neighbors to Kocuria flava (GenBank accession no. MT773277) and Pantoea dispersa (GenBank accession no. MT766308), respectively. The potential isolate Y4 was found to exhibit adhesion, auto-aggregation, co-aggregation, and weak biofilm activity. It also exhibited a high level of antimicrobial activity and antibiotic susceptibility. The safety of K. flava Y4 isolate, which is proposed to be a probiotic, was evaluated through acute oral toxicity test and biogenic amine production test. Moreover, the preservation potential of isolate Y4 was assessed through application on fruits under different temperatures. Thus, our results confirmed that Kocuria flava Y4 is a prospective probiotic and could also be used for the preservation of fruits.

Understanding the fundamentals of microbial remediation with emphasize on metabolomics

The post-genomic tool metabolomics is a great advancement in science and technology which acquires novel strategies and pathways to analyze various biological compounds. Metabolomics aids in retrieving the qualitative and quantitative data from the various biological system. The current review is focused on the application of metabolomics in bioremediation and helps to focus on the xenobiotic compounds which are discharged into the environment and have long term impact. The microbial based biodegradation can be effectively used along with the combination of metabolomic approach for a better understanding of the breakdown of certain recalcitrant. Additionally, this review also discusses the candidate gene approach which helps to comprehend the functional analysis of microbial genes in response to different contaminants. Therefore, this review intends to discuss the metabolomics in bioremediation by studying the complete set of metabolites involved during the process of degradation and their interaction with the environment.

Phytoremediation of Heavy Metals in Tropical Soils an Overview

The geomorphological characteristics of the materials inherent in tropical soils, in addition to the excessive use of fertilizers and pesticides, industrial waste and residues, and novel pollutants derived from emerging new technologies such as nanomaterials, affect the functionality and resilience of the soil-microorganism-plant ecosystem; impacting phytoremediation processes and increasing the risk of heavy metal transfer into the food chain. The aim of this review is to provide a general overview of phytoremediation in tropical soils, placing special emphasis on the factors that affect this process, such as nanoagrochemicals, and highlighting the value of biodiversity among plant species that have the potential to grow and develop in soils impacted by heavy metals, as a useful resource upon which to base further research.

Biodegradation and biosorption of Reactive Red 120 dye by immobilized Pseudomonas guariconensis: Kinetic and toxicity study

Reactive dyes are pernicious pollutants in textile effluent, which are to be treated passably before discharging into the environment. In the present study, a potential dye degrading bacterial strain Pseudomonas guariconensis was isolated from paddy rhizosphere and was characterized by 16S rRNA gene sequencing. The biodegradation ability of the strain was evaluated by time-based study with immobilized bacterial cells in calcium alginate biocarrier matrix and also with free cells. The results indicated that the strain exhibited maximum degradation of 91% when immobilized in the biocarrier matrix. The enzymatic study revealed the production of oxidoreductase enzymes. The degraded products were identified as 2-amino-3-phenylpropanoic acid and benzoquinone by gas chromatography-mass spectroscopy (GC-MS) analysis, and a degradative pathway was derived based on the enzymatic profile. A packed bed column was designed using P. guariconensis VITSAJ5 immobilized in calcium alginate beads as a biosorbent for the removal of Reactive Red 120. The immobilized bacterial cells exhibited 87% uptake of RR120, whereas the nonimmobilized bacterial cells exhibited a maximum uptake of 37%. The phytotoxicity analysis by seed germination assay revealed an enhanced plumule and radicle length, indicating the nontoxic byproducts after the treatment of Reactive Red 120 by VITSAJ5 compared to the untreated Reactive Red 120 solution. PRACTITIONER POINTS: Current study is the first report on Pseudomonas guariconensis capable of degrading reactive dyes (Reactive Red 120) It was observed that the degradation potential was maximum when cells were immobilized with Ca-Ag biocarrier matrix Breakdown metabolism of Reactive Red 120 was derived through pathway prediction Employing immobilized bacteria in a packed bed column found to possess a prominent biosorption ability on the matrix enhancing the degradation process Toxic reactive dye was converted into nontoxic compounds, evidenced by phytotoxicity studies.

Staphylococcus xylosus VITURAJ10: Pyrrolo [1,2α] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) (PPDHMP) producing, potential probiotic strain with antibacterial and anticancer activity

In the present study bacterial strain (VITURAJ10), isolated from goat milk was characterised for its probiotic potential. The various probiotic traits included tolerance to acidic pH (up to pH 3), bile salts (0.3%) and transit gut environment (simulated with digestive juices such as pepsin, Oxgall and pancreatin). The isolate could withstand high NaCl concentrations in the growth medium, showed inability to produce hemolysin and did not hydrolyse mucin. VITURAJ10 was capable of forming biofilm and produced exopolysachharide. The bioactive metabolites produced by the isolate were extracted and they showed growth suppressing activity towards pathogenic strains such as Escherichia coli, Salmonella enterica and Staphylococcus aureus. The crude extract was fractionated with solid phase extraction (SPE) chromatography and the fractions 10 and 12 were found to be effective against the bacterial pathogens. The fractions were further gauged for cytotoxic activity against MCF-7 cell line by MTT assay. The biologically significant compounds identified through GC-MS and FT-IR analysis in the fractions were, Actinomycin D, Pyrrolo [1,2α] Pyrazine-1,4-Dione, Hexahydro-3-(2-Methylpropyl)- (PPDHMP) and Didemnin B. The phylogenetic taxonomy of the isolate revealed the isolate to be the closest neighbour of Staphylococcus xylosus VITURAJ10 (GenBank accession no. KX770743.1) as per the16S rRNA gene sequencing and subsequent phylogenetic tree analysis.