Physico-Chemical Aspects and Complete Bacterial Community Composition Analysis of Wasp Nests

Wasps are a group of social insects that build a house, known as a nest, from locally available building materials cemented by their saliva and secretions. Similar to termite nests, there could be many beneficiary bacteria present in their house that can play an important part in maintaining sustainability in soil ecosystems. Thus, the present study was initiated with a physico-chemical characterization of wasp nests collected from residential and forest zones, followed by unconfined compressive strength (UCS) and X-ray diffraction (XRD) analysis to identify major associated minerals. Further, MiSeq Illumina sequencing of the 16S rRNA gene (V3–V4 regions) was carried out to analyze complete bacterial community composition of wasp nests. The resulting data showed a dominance of Actinobacteria followed by Proteobacteria in both nests. Kaistobacter and Phycicoccus were the dominant genera in each type of wasp nest. It was concluded that wasp nests are an abundant source to isolate bacteria that can potentially be helpful in soil biogeochemical cycling and fertility, antibiotics production and bioremediation

Biosurfactants: Eco-Friendly and Innovative Biocides against Biocorrosion

Corrosion influenced by microbes, commonly known as microbiologically induced corrosion (MIC), is associated with biofilm, which has been one of the problems in the industry. The damages of industrial equipment or infrastructures due to corrosion lead to large economic and environmental problems. Synthetic chemical biocides are now commonly used to prevent corrosion, but most of them are not effective against the biofilms, and they are toxic and not degradable. Biocides easily kill corrosive bacteria, which are as the planktonic and sessile population, but they are not effective against biofilm. New antimicrobial and eco-friendly substances are now being developed. Biosurfactants are proved to be one of the best eco-friendly anticorrosion substances to inhibit the biocorrosion process and protect materials against corrosion. Biosurfactants have recently became one of the important products of bioeconomy with multiplying applications, while there is scare knowledge on their using in biocorrosion treatment. In this review, the recent findings on the application of biosurfactants as eco-friendly and innovative biocides against biocorrosion are highlighted

The Potential of Microbial Fuel Cells for Remediation of Heavy Metals from Soil and Water—Review of Application

The global energy crisis and heavy metal pollution are the common problems of the world. It is noted that the microbial fuel cell (MFC) has been developed as a promising technique for sustainable energy production and simultaneously coupled with the remediation of heavy metals from water and soil. This paper reviewed the performances of MFCs for heavy metal removal from soil and water. Electrochemical and microbial biocatalytic reactions synergistically resulted in power generation and the high removal efficiencies of several heavy metals in wastewater, such as copper, hexavalent chromium, mercury, silver, thallium. The coupling system of MFCs and microbial electrolysis cells (MECs) successfully reduced cadmium and lead without external energy input. Moreover, the effects of pH and electrode materials on the MFCs in water were discussed. In addition, the remediation of heavy metal-contaminated soil by MFCs were summarized, noting that plant-MFC performed very well in the heavy metal removal

A biological route for producing low energy binders

Building materials almost certainly consist of some form of binders. Presently used binders, such as cement, consume a high amount of energy consumption in its manufacturing and transportation. This paper reports a biomimetic strategy for production of binders at ambient conditions based on microbially induced calcium carbonate precipitation (MICP). Microorganisms such as Sporosarcina pasteurii and Bacillus megaterium are used for precipitation of calcium carbonate on substrates such as concrete and brick. The deposition reduces permeability and corrosion in the substrate. The paper demonstrates the methods of increasing efficiency and cost reduction of the process. Effect of microbial action on strength, permeability of concrete, particularly near its surface, and ingress of moisture and chloride are discussed. Result of calcite deposition on reinforced concrete in terms of current passed when exposed to harsh corrosive conditions and Icorr is presented. Further, the role of MICP has been presented to develop highly efficient and durable soil-cement brick that requires very low embodied energy for production and also emit least CO2.The current work demonstrates that production of biocalcification by urease producing bacteria can at least partially replace the industrial binders and provide a more sustainable alternative

Biogenic treatment improves the durability and remediates the cracks of concrete structures

Microbially induced calcium carbonate precipitation is a naturally occurring biological process that has various applications in remediation and restoration of range of building materials. In the present study the role of bacteria Bacillus sp. on the durability properties and remediation of cracks in cementitious structures were studied. “Biocement” induced by a Bacillus sp. lead to more than 50% reduction in the porosity of mortar specimens, while chloride permeability of concrete changed from “moderate” to “very low” as indicated by rapid chloride permeability test. The bacteria successfully healed the simulated cracks of depths including 27.2 mm in cement mortars with increase in the compressive strength as high as 40% of that of control. The results clearly showed microbially induced calcium carbonate precipitation can be applied for various building materials for remediation of cracks and enhancement of durability.by Varenyam Achal, Abhijeet Mukerjee, M. Sudhakara Redd

A review on utilization of pozzolanic materials in microbial concrete

Microbial calcite precipitation has been intensively studied recently for the improvement of compressive strength and durability of concrete, including those with pozzolanic materials such as metakaolin (MK), fly ash (FA), and silica fume (SF). Such materials possess high pozzolanic activity and have become an essential part of high strength and high performance concrete mix design. However, when replacing cement at high proportion, it has been found that such materials can cause a decrease of freeze-thaw resistance and early age strength of concrete. To remedy the defects, microbial calcite precipitation, a continuous extracellular cementation process dominated by bacteria, has been used to improve the engineering properties of such concrete. This article gives an overview of the biocementation process for the improvement of compressive strength and durability of concrete where cement was partially replaced with mk, fa, and sf. It has been found that properties like compressive strength, and durability of pozzolanic concrete can be improved with microbial calcite precipitation

Contrasting Performance and Different Tolerance of Chestnut Rose and Grape to Excess Manganese

Grape (cultivar Jinshou) and chestnut rose (cultivar Gui 4) were exposed to excess manganese (Mn) treatments to characterize the physiological basis for Mn tolerance in woody plants. Chestnut rose exhibited a high sensitivity to this environmental constraint whereas grape appeared rather tolerant to Mn excess. Stomatal density and closure rate were affected by excess Mn in chestnut rose and brittleness of the leaf vein was reported as a novel Mn toxicity symptom in this species. Linear reductions in biomass accumulation and photosynthetic pigment concentrations with increasing Mn level were observed in chestnut rose but not in grape, except under the extremely high Mn concentration (118 mM). Our results showed that the contrasting performances between the two species were related to the differences in ion transfer and homeostasis. Mn was readily allocated to the photosynthetic organ in chestnut rose but was mainly restricted to the roots in grape. Excess Mn caused iron (Fe) and nitrogen (N) deficiencies in chestnut rose but not in grape. The synthesis of antioxidant phenylpropanoid compounds and chelating phytochelatins were activated in Mn-treated grape but strongly repressed in chestnut rose. The importance of these parameters in the overall strategy of Mn tolerance in grape is discussed. © 2012 Springer Science+Business Media, LLC