Vishal Tripathi

Remediation and management of POPs-contaminated soils in a warming climate: challenges and perspectives.

There is a growing global priority for the remediation and management of persistent organic pollutants (POPs)-contaminated soil since these POPs are one of the toxic groups of chemical pollutants and listed under the Stockholm Convention for global elimination. They are potentially hazardous to living organism because of their higher degree of halogenations, inclination to bioaccumulate in the lipid component, and their resistance to natural degradation (Weber and Varbelow 2013; Torres et al. 2013a, b; Weber et al. 2013; Götz et al. 2013; Younas et al. 2013; Nurzhanova et al. 2013; Sun et al. 2013; Aliyeva et al. 2013; Oliaei et al. 2013; Xu et al. 2013; Vijgen et al. 2013; Miguel et al. 2013; Meire et al. 2013; Domínguez-Cortinas et al. 2013; Wu et al. 2013). Once enter into the pedosphere, these compounds can redistribute and partition into other environmental compartments by various physical, chemical, and biological processes such as adsorption onto soil particles, adsorption onto plant root tissues, volatilization, long-range atmospheric transport, long-range marine transport, microbial degradation and leaching, etc. Recently, nine additional “new” POPs were included in the Stockholm Convention POPs list so that the current list is having a total of 21 pollutants (Vijgen et al. 2011). Among the POPs, organochlorine pesticides (OCPs) constitute a major group. Despite the fact that most of these OCPs are banned or restricted for use in many countries, the contaminated soils and obsolete stock piles continue to have a significant impact on a number of ecosystems worldwide and pose a serious problem of bioaccumulation of POPs in soil to grazing animals and other livestock (Perugini et al. 2012) and the potential to pollute milk/dairy products (Konuspayeva et al. 2011; Tato et al. 2011) and eggs (Helgason et al. 2008; Leat et al. 2011). Huge amount of POPs polluted soils are found in different parts of the world (Abhilash and Singh, 2009; Vijgen et al. 2011; Weber and Varbelow 2013; Torres et al. 2013a, b, c; Weber et al. 2013; Abhilash et al. 2013a, b). Although most of the developed countries have already initiated the clean-up of POPs-contaminated sites and developed suitable methodologies for the ecotoxicological risk profiling of such POPscontaminated soils (Fisk et al. 2005; Letcher et al., 2010; Riva et al. 2011), more global and regional efforts should be taken to assess the extent of POPs contamination in developing countries including India and suitable methodologies should be framed to assess the actual risk posed by these POPscontaminated soils to humans beings, livestock, and other ecosystems (Abhilash and Yunus 2011). However, on the other hand, the burgeoning world population exerts tremendous pressure on soil for food, biomass and bioenergy production, and many more (Banwart 2011). It is projected that in order to meet the food demand of a growing population, the agriculture has to be highly intensified to meet an expected 50 % increase in food demand by 2030, and possibly by doubling by 2050 (Banwart 2011; Godfray 2010). Therefore, there is a huge cry for the protection of our soil resources from further damage and the remediation and restoration of already contaminated soils in an urgent basis. Although a lot of chemicaland engineeringResponsible editor: Philippe Garrigues

Phytoextraction and dissipation of lindane by Spinacia oleracea L.

Remediation and management of organochlorine pesticide (OCPs) contaminated soil is becoming a global priority as they are listed in the Stockholm list of persistent organic pollutants (POPs) for global elimination. Lindane is a OCPs candidate recently included in the Stockholm list. However, India has an exemption to produce lindane for malaria control. Because of its widespread use during the last few decades, lindane contaminated soils are found in almost all parts of India. Since phytoremediation is widely acknowledged as an innovative strategy for the clean-up of contaminated soils; the present study was aimed to evaluate the phytoextraction and dissipation of lindane by a leafy vegetable Spinacia oleracea L (Spinach). The test plant was grown in different concentrations of lindane (5, 10, 15 and 20 mg kg(-1)) and harvested at 10, 30 and 45 days. At 45 days, the concentrations of lindane in root and leaf of Spinach growing in four different concentrations were reached up to 3.5, 5.4, 7.6 and 12.3 mg kg(-1) and 1.8, 2.2, 3 and 4.9 mg kg(-1), respectively. There was a significant difference (p<0.01) in the dissipation of lindane in vegetated and non-vegetated soil. Moreover, the residual lindane in four experiments was reduced to 81, 76, 69 and 61 percent, respectively. The experimental results indicate that Spinach can be used for the phytoremediation of lindane. However, more studies are required to prevent the toxicity of harvested parts.

Biotechnological Advances for Restoring Degraded Land for Sustainable Development

Global land resources are under severe threat due to pollution and unsustainable land use practices. Restoring degraded land is imperative for regaining ecosystem services, such as biodiversity maintenance and nutrient and water cycling, and to meet the food, feed, fuel, and fibre requirements of present and future generations. While bioremediation is acknowledged as a promising technology for restoring polluted and degraded lands, its field potential is limited for various reasons. However, recent biotechnological advancements, including producing efficient microbial consortia, applying enzymes with higher degrees of specificity, and designing plants with specific microbial partners, are opening new prospects in remediation technology. This review provides insights into such promising ways to harness biotechnology as ecofriendly methods for remediation and restoration.

Plant Growth-Promoting Microorganisms for Environmental Sustainability

Agrochemicals used to meet the needs of a rapidly growing human population can deteriorate the quality of ecosystems and are not affordable to farmers in low-resource environments. Here, we propose the use of plant growth-promoting microorganisms (PGPMs) as a tool for sustainable food production without compromising ecosystems services.

Bioremediation for Fueling the Biobased Economy

Increasing CO2 emission, land degradation, and pollution are major environmental challenges that need urgent global attention. Remediation strategies are essential for tackling these issues concurrently. Here we propose integrating bioremediation with CO2 sequestration for revitalizing polluted land while deriving bioproducts from renewable and waste biomass for fueling a sustainable bioeconomy.

Book Review: Principles of Plant-Microbe Interactions: Microbes for Sustainable Agriculture

The significance of plant-microbe interactions in sustainable agriculture is enormous. These interactions may be negative such as the host-pathogen interactions leading to the disease development in plants or positive likes the interaction of the plants with the beneficial soil microbiota for stimulating the plant growth, conferring biotic, and abiotic stress tolerance in plants and helping the plants for the revitalization of contaminated and degraded soils (Abhilash et al., 2012). Apart from that, the beneficial microorganisms influence the resource allocation between root and shoot, biodiversity and also mediate the above-ground below ground interactions with herbivores and other natural enemies of the plants. Moreover, such dialogues between plant and microbes can modify the chemical, physical, and biochemical properties of the soil. The root exudate secreted by the plant allocates carbon and nutrients to the soil in the form of low molecular weight sugars, amino acids, and organic acids, polymerized sugars (e.g., mucilage), root border cells and dead root cap cells. Plant secretes phytosiderophores that help in sequestration of metallic micronutrients from the soil. Root exudates also contains secondary metabolites which help in the communication of plant and microbes. However, these interactions are intriguingly complex and dynamic and quite difficult to decipher as they takes places at different interfaces such as rhizosphere, phyllosphere, and endosphere. Therefore, a deep understanding of the interwoven processes taking place at the above interfaces is essential for disentangling the contribution of the each and every player for the ecosystem wellbeing. Thus, it is imperative to understand the key processes of the plant-microbe interactions in relation to assessing the contribution of the plant associated microorganisms to sustainable agriculture, ecosystem restoration, biomass and bioenergy production and mitigating the adverse impacts of climate change (Saleem and Moe, 2014). In this context, the book “Principles of Plant-Microbe Interactions: Microbes for Sustainable Agriculture,” edited by Ben Lugtenberg (2015) is a topical and timely contribution on plant-microbe interactions and offers a great hope for harnessing such beneficial interactions for making agriculture as a sustainable enterprise. Though literature provides ample information on plant-microbe interactions, the current book is first of its kind to discuss not only the interactions of microbes with plants but also the interactions of other important but often ignored players such as nematodes, insects, and pests. The book also discusses various ecological, economic and social aspects related to the plant-microbe based packages right from exploiting the symbiotic relationship to the development of genetically modified organisms for enhancing the sustainability of agriculture. The editor did his level best to incorporating the views of leading scientists and industrial professionals working in the concerned area to give a complete package to students, teachers, academicians, policy makers, young entrepreneurs, biotech, and food industry specialists and policy makers for understanding the plant-microbe interactions and successful exploitation for the benefit of the society. Moreover, the simple and lucid presentation of the crosstalk between microbes and the plants taking place at different interface is good enough to quenches the thirst of the readers from basic to applied and advanced molecular developments in the area. The editor meticulously divided the book into eight parts for detailing the fundaments of plant-microbe interactions to the application level such as (i) the elucidation of the microbial diversity associated with the plant system and its specific role (ii) the diversity of the phytopathogens, pests mediated crop damage, plant defense, and dilemma about the transgenic crops in public (iii) role of biocontrol agents and transgenics in plant disease resistance and post-harvest loss (vi) mechanism of different plant growth promoting microorganism and arbuscular mycorrhizae in host plant nutrients, water use efficiency and rhizoremediation (v) merit and the challenges in recent techniques like culture independent molecular tools and confocal microscopy for unraveling the rhizosphere microbiome and its interaction with the host plant (vi) the commercialization of microbial inoculum for the plant growth and disease control (vii) harnessing of plant-microbe interactions as a low-input biotechnology and finally (viii) manipulating the plant-microbe interactions for human wellbeing. The book starts with the fundamentals of the plant-microbe interactions by unraveling the rhizospheric, phyllospheric, and endospheric microbial world associated with the plant system. The book helps in exploring the diverse microbial partners, its importances and mechanisms of the actions for proper understanding of the topic. It also elucidates the structural and functional details of microbial cell surfaces and its role in exchanging the signals from the exterior to the intracellular milieu. Interestingly, the book also exploring the role of myriad phytopathogens such as bacteria, fungi, nematodes, viruses, and pests its symptomatology, infections mechanisms along with plant immune response to infections and disease control mediated by the biocontrol agents. Apart from the biocontrol activity, the editor has also made an attempt to address the role of the plant associated microbiome for solubilizing the essential nutrients in soil and also for promoting the plant growth and yields even under adverse environmental conditions. The book also reminds that certain modifications in the microbial traits and rhizosphere environment will enhance the productivity of the agroecosystems. Importantly, the students and restoration workers will get in depth knowledge about various strategies for reshaping the rhizosphere microbiome. Similarly, transferring the genetic machinery of the nitrogen fixation in to non-legume plants also provides new vistas in sustainable agriculture. The book also unveil the concepts and issues related with the formulation, efficacy testing based on the European Plant Protection Organization, process of registration, and the global commercialization of the microbial inoculums in detail. The major global producers of the microbial inoculums are also detailed in this book. Although microbes like Pseudomonas sp., Bacillus sp., and Trichoderma sp. are the most suitable bio-inoculants, there are always outstanding concerns regarding the shell-life and field performance of these inoculums. Interestingly, the Editor has paid attention to detail the next generation ideal bioinoculants with the concepts of the enhanced stability, carrier suitability, spore forming capability, better inoculation strategies, seed–soil inoculation, microbial inoculants consortium application including bacteria, and fungi. It has been generally postulated that under changing climatic conditions, the increasing atmospheric CO2 will have a fertilization effect on plants and will increase the allocation of nutrients in above- and belowground parts. Hence, it is unclear that how such change will go to affect the plant-microbe interactions at ecosystem level (Abhilash and Dubey, 2014). Although such changing conditions will have a significant impact on plant-microbe interactions, the present book does not shed light on this important issue. Similarly, the exploitation of plant-microbe interactions for the clean-up of contaminated soils has been presented in accordance to the clean-up of organic pollutants with little emphasis on heavy metal and mixed pollutants (organic and inorganic) contaminated soil. Furthermore, in a time when next generation sequencing technologies have been completely revolutionized the microbial community analysis, the current book describes the microbial community analysis mainly on the basis of Denaturing Gradient Gel Electrophoresis. Nevertheless, we enjoyed reading this book as the editor tried to cover almost all fundamental and applied aspects of the plant-microbe interactions. As a final word, the book can be described as a book for all.