Application of Response Surface Methodology (RSM) in the statistical evaluation of biodiesel production from the neutral lipids of the Coelastrella-Nannochloropsis consortium.

The paramount challenge in economically workable microalgal biodiesel production is the selection of a competent catalyst to improve the fatty acid methyl ester yield with desirable fatty acid composition. Though countless researchers have explored different homogeneous and heterogeneous catalysts to improve the transesterification efficacy, achieving greater biodiesel production from the neutral lipids of the microalgal consortium using a statistical tool, response surface methodology is scarce. Thus, the present study applied Response surface methodology to statistically analyze the biodiesel production from the neutral lipids of the indigenous Coelastrella-Nannochloropsis consortium (CNC) on the way to commercial feasibility. Onset of the study, the neutral lipids and acid value of the CNC were determined to be 18.74% and 2.73%, respectively. The transesterification of the neutral lipids of CNC was optimized through the coded factors in the RSM for various reaction parameters as combined influence viz., (i) Catalyst dose: methanol volume, (ii) Catalyst dose: reaction time; (iii) Catalyst dose: reaction temperature, (iv) Time: temperature, (v) time: methanol volume, (vi) temperature: methanol volume. Based on the ANOVA, coefficient determination, 2% KOH, 2 h time, 70 °C temperature, and 9 mL methanol volume were ascertained to be optimal values to accomplish 92% biodiesel production. Further, the biodiesel has desirable palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids, with palmitic acid as the prevalent fatty acid contributing 16-18%. In addition, the tested fuel properties of CNC biodiesel satisfy international biodiesel standards.

Bubble column photobioreactor (BCPR) for cultivating microalgae and microalgal consortium (Co-CC) with additional CO2 supply for enhancing biomass, lipid, and preferable fatty acids production.

The present study has designed and developed a 5 L bubble column photobioreactor (BCPR) to investigate two microalgal strains Chlorella sp. S-01, Chlorella sp. S-02 and their consortium Co-CC (Chlorella sp. S-01 + Chlorella sp. S-02) at 0.03, 5, and 10% CO2 supply for biomass and lipid production. The dry cell weight of Chlorella sp. S-01, Chlorella sp. S-02 and Co-CC were, respectively about 1.41, 1.32, and 1.39 g/L on the 20th day without CO2 supply, while it was 1.76, 1.61, and 1.87 g/L, respectively at 10% CO2 supply and similarly, chlorophyll-a content was higher in 10% CO2 supplied condition over control. Interestingly, Co-CC grown at all the CO2 concentrations showed similar lipid content between 19.30 and 1F9.41%. As an integrated refinery approach, de-oiled biomass of Co-CC was subjected to carbohydrates and protein estimation and found that 46.2% and 30.80% in 10% CO2 supply condition in BCPR. Lipid extracted from the Co-CC grown under 0.03, 5, and 10% CO2 supply in 5L BCPR was converted to biodiesel, and the biodiesel yield was estimated to be 62.78%. Further, the fatty acid profile of Co-CC grown at 10% CO2 showed higher levels of C16:0, C16:1, C18:1, and monounsaturated fatty acids contents over other CO2 supplied conditions. Biodiesel of Co-CC showed favourable fuel properties such as density, higher heating value, oxidative stability, CFPP, viscosity, degree of unsaturation, saponification value, and cetane number, which were also in accordance with ASTM, and EN, biodiesel standards.

Comprehensive Review on the Use of Biocides in Microbiologically Influenced Corrosion.

A microbiologically influenced corrosion (MIC) causes huge economic losses and serious environmental damage every year. The prevention and control measures for MIC mainly include physical, chemical, and biological methods. Among them, biocide application is the most cost-effective method. Although various biocides have their own advantages in preventing and treating MIC, most biocides have the problem of polluting the environment and increasing microorganism resistance. Therefore, it has stimulated the exploration of continuously developing new environmentally friendly and efficient biocides. In this review, the application advantages and research progress of various biocides used to prevent and control MIC are discussed. Also, this review provides a resource for the research and rational use of biocides regarding MIC mitigation and prevention.

Review on Microbially Influenced Concrete Corrosion.

Microbially influenced concrete corrosion (MICC) causes substantial financial losses to modern societies. Concrete corrosion with various environmental factors has been studied extensively over several decades. With the enhancement of public awareness on the environmental and economic impacts of microbial corrosion, MICC draws increasingly public attention. In this review, the roles of various microbial communities on MICC and corresponding protective measures against MICC are described. Also, the current status and research methodology of MICC are discussed. Thus, this review aims at providing insight into MICC and its mechanisms as well as the development of protection possibilities.

Exopolymeric substances production by Bacillus cereus KMS3-1 enhanced its biosorption efficiency in removing Cd2+ and Pb2+ in single and binary metal mixtures.

The present study investigated the growth, exopolymeric substance (EPS) production, and biosorption efficiency of strain Bacillus cereus KMS3-1 in the Cd2+ and Pb2+ ions containing single and binary metal-treated broth (50 mg/L). In addition, the interaction of the KMS3-1 strain with Cd2+ and Pb2+ ions in single and binary metal-treated broths was investigated using SEM-EDS, FTIR, and XRD analyses. The results showed that the biosorption efficiency (%) and EPS production of KMS3-1 biomass in both single and binary metal-treated broths had increased with increasing incubation time and were higher for Pb2+ ions than for Cd2+ ions. In the single and binary metal-treated broths, the maximum biosorption efficiency of KMS3-1 for Pb2+ ions were 70.8% and 46.3%, respectively, while for Cd2+ ions, they were 29.3% and 16.8%, respectively, after 72 h. Moreover, the biosorption efficiency of strain KMS3-1 for both metal ions was dependent on its EPS production and peaked at the maximum EPS production. The copious EPS production by KMS3-1 was observed in metal-treated media (50 mg/L), in the following order: Pb2+ ions (1925.7 µg/mL) > binary metal mixtures (1286.8 µg/mL) > Cd2+ ions (1185.5 µg/mL), > control (1099 µg/mL) after 72 h of incubation. This result indicates that the metal biosorption efficiency of the KMS3-1 strain was enhanced by the increased EPS production in the surrounding metal-treated broth. SEM-EDS and FTIR characterization studies revealed that the KMS3-1 biomass effectively adsorbed Cd2+ and Pb2+ ions from the medium by interacting with their surface functional groups (hydroxyl, carbonyl, carboxyl, amide, and phosphate). Moreover, the biosorbed Cd2+ and Pb2+ ions were transformed into CdS and PbS, respectively, by the KMS3-1 biomass. This study suggests that the Bacillus cereus KMS3-1 strain may be a promising candidate for the treatment of metal contamination.

Multifarious extraction methodologies for ameliorating lipid recovery from algae.

Amongst the current alternatives, algae were proven to be a promising source of biofuel, which is renewable and capable of meeting world demand for transportation fuels. However, a suitable lipid extraction method that efficiently releases the lipids from different algal strains remains a bottleneck. The multifarious pretreatment methods are prevalent in this field of lipid extraction, and therefore, this article has critically reviewed the various lipid extraction methods for ameliorating the lipid yield from algae, irrespective of the strains/species. Physical, mechanical, and chemical are the different types of pretreatment methods. In this review, methodologies such as homogenization, sonication, Soxhlet extraction, microwave treatment, and bead-beating, have been studied in detail and are the most commonly used methods for lipid extraction. Specific advanced/emerging processes such as supercritical CO2 extraction, ionic liquid, and CO2 switchable solvent-based algal lipid extraction are yet to be demonstrated at pilot-scale, though promising. The extraction of lipids has to be financially conducive, environmentally sustainable, and industrially applicable for further conversion into biodiesel. Hence, this paper discusses variable pretreatment for lipid extraction and imparts a comparative analysis to elect an efficient, economically sound lipid extraction method for pilot-scale biodiesel production.

Biosynthesis of copper oxide nanoparticles using Rubia cordifolia bark extract: characterization, antibacterial, antioxidant, larvicidal and photocatalytic activities.

Rubia cordifolia represents the pivotal plant resource belonging to traditional Chinese medicine and Indian Ayurveda. The present study aims to synthesize biocompatible copper oxide nanoparticles (CuONPs) using R. cordifolia bark extracts, characterize the incumbent chemical transitions, and explore their biomedical and environmental applications. The absorbance peak between 250 and 300 nm clearly demonstrates the formation of CuONPs in the UV-visible spectrum. Fourier transform infrared spectroscopy results showed the presence of functional groups essential for copper ion reduction. Field emission scanning electron microscopy (FE-SEM) and dynamic light scattering analysis revealed that the CuONPs are spherical-shaped with a mean particle size of 50.72 nm. Additionally, the zeta potential demonstrates its robustness at 11.2 mV. X-ray diffraction pattern showed mixed phases (Cu, Cu2O, and CuO) of cubic monoclinic crystalline nature. CuONPs exhibited noticeable antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus cereus) pathogenic bacteria. Bacterial cell damages were affirmed through FE-SEM imaging when treated with CuONPs. Further, CuONPs demonstrated considerable antioxidant activities by quenching free radicals such as DPPH (60.75%), ABTs (70.88%), nitric oxide (65.48%) and reducing power (71.44%) in a dose-dependent way. CuONPs showed significant larvicidal activity against Aedes aegypti (65 ± 8.66%), Anopheles stephensi (80 ± 13.69%), and Culex quinquefasciatus (72 ± 13.04%) mosquito larvae. The photocatalytic activity of the CuONPs demonstrates the methylene blue (81.84%) and crystal violet (64.0%) dye degradation potentials, indicating the environmental bioremediation efficacy. Hence the present study is the first report in accounting for the versatile applications of the phyto-CuONPs. Moreover, the green synthesis of CuONPS has future applications in designing the drug for life-threatening diseases and various environmental issues.

Soil microbial community assembly model in response to heavy metal pollution.

Heavy metal pollution affected the stability and function of soil ecosystem. The impact of heavy metals on soil microbial community and the interaction of microbial community has been widely studied, but little was known about the response of community assembly to the heavy metal pollution. In this study, we collected 30 soil samples from non (CON), moderately (CL) and severely (CH) contaminated fields. The prokaryotic community was studied using high-throughput Illumina sequencing of 16s rRNA gene amplicons, and community assembly were quantified using phylogenetic-bin-based null approach (iCAMP). Results showed that diversity and composition of both bacterial and archaeal community changed significantly in response to heavy metal pollution. The microbial community assembly tended to be more deterministic with the increase of heavy metal concentration. Among the assembly processes, the relative importance of homogeneous selection (deterministic process) increased significantly (increased by 16.2%), and the relative importance of drift and dispersal limitation (stochastic process) decreased significantly (decreased by 11.4% and 5.4%, respectively). The determinacy of bacterial and archaeal community assembly also increased with heavy metal stress, but the assembly models were different. The deterministic proportion of microorganisms tolerant to heavy metals, such as Thiobacillus, Euryarchaeota and Crenarchaeota (clustered in bin 32, bin59 and bin60, respectively) increased, while the stochastic proportion of microorganisms sensitive to heavy metals, such as Koribacteraceae (clustered in bin23) increased. Therefore, the heavy metal stress made the prokaryotic community be deterministic, however, the effects on the assembly process of different microbial groups differed obviously.

Integrated network analysis reveals that exogenous cadmium-tolerant endophytic bacteria inhibit cadmium uptake in rice.

Most previous studies have focused on the diversity and species richness of microbial communities, however, understanding the interactions between species and detecting key functional members of the community can help us better understand how microorganisms perform their functions. In this study, the response of the rice plant microbial community to the inoculation of cadmium-resistant endophytic bacterium R5 (Stenotrophomonas) was investigated for the first time using a microbial phylogenetic molecular ecological network. The results showed that inoculation of R5 changed the topological characteristics of the microbial network in rice plants, with the resulting network displaying stronger complexity and interaction in roots and aboveground parts, indicating that inoculation of R5 provided favorable conditions for microbial interactions. In addition, these interactions may be related to the absorption and transportation of cadmium by rice. Under the exogenous addition of R5, the network interactions of the rice plant microbial community were more inclined to cooperation. Both in the roots and aboveground parts of rice, the plant Cd content showed a decrease as the complexity and connectivity of the network increased, suggesting that complex microbial networks may be more beneficial to rice than simple microbial networks because as they were more adaptive and resistant to unfavorable environments. After inoculation with the R5 strain, the negative interaction with Cd content in rice plants increased significantly, and there might be more synergy between the microbial community and plants to jointly inhibit the absorption and transportation of Cd.

Exopolysaccharide Produced by Probiotic Bacillus albus DM-15 Isolated From Ayurvedic Fermented Dasamoolarishta: Characterization, Antioxidant, and Anticancer Activities.

An exopolysaccharide (EPS) was purified from the probiotic bacterium Bacillus albus DM-15, isolated from the Indian Ayurvedic traditional medicine Dasamoolarishta. Gas chromatography-mass spectrophotometry and nuclear magnetic resonance (NMR) analyses revealed the heteropolymeric nature of the purified EPS with monosaccharide units of glucose, galactose, xylose, and rhamnose. Size-exclusion chromatography had shown the molecular weight of the purified EPS as around 240 kDa. X-ray powder diffraction analysis confirmed the non-crystalline amorphous nature of the EPS. Furthermore, the purified EPS showed the maximum flocculation activity (72.80%) with kaolin clay and emulsification activity (67.04%) with xylene. In addition, the EPS exhibits significant antioxidant activities on DPPH (58.17 ± 0.054%), ABTS (70.47 ± 0.854%) and nitric oxide (58.92 ± 0.744%) radicals in a concentration-dependent way. Moreover, the EPS showed promising cytotoxic activity (20 ± 0.97 µg mL-1) against the lung carcinoma cells (A549), and subsequent cellular staining revealed apoptotic necrotic characters in damaged A549 cells. The EPS purified from the probiotic strain B. albus DM-15 can be further studied and exploited as a potential carbohydrate polymer in food, cosmetic, pharmaceutical, and biomedical applications.

Bacterial adaptive strategies to cope with metal toxicity in the contaminated environment - A review.

Heavy metal contamination poses a serious environmental hazard, globally necessitating intricate attention. Heavy metals can cause deleterious health hazards to humans and other living organisms even at low concentrations. Environmental biotechnologists and eco-toxicologists have rigorously assessed a plethora of bioremediation mechanisms that can hamper the toxic outcomes and the molecular basis for rejuvenating the hazardous impacts, optimistically. Environmental impact assessment and restoration of native and positive scenario has compelled biological management in ensuring safety replenishment in polluted realms often hindered by heavy metal toxicity. Copious treatment modalities have been corroborated to mitigate the detrimental effects to remove heavy metals from polluted sites. In particular, Biological-based treatment methods are of great attention in the metal removal sector due to their high efficiency at low metal concentrations, ecofriendly nature, and cost-effectiveness. Due to rapid multiplication and growth rates, bacteria having metal resistance are advocated for metal removal applications. Evolutionary implications of coping with heavy metals toxicity have redressed bacterial adaptive/resistance strategies related to physiological and cross-protective mechanisms. Ample reviews have been reported for the bacterial adaptive strategies to cope with heavy metal toxicity. Nevertheless, a holistic review summarizing the redox reactions that address the cross-reactivity mechanisms between metallothionein synthesis, extracellular polysaccharides production, siderophore production, and efflux systems of metal resistant bacteria are scarce. Molecular dissection of how bacteria adapt themselves to metal toxicity can augment novel and innovative technologies for efficient detoxification, removal, and combat the restorative difficulties for stress alleviations. The present comprehensive compilation addresses the identification of newer methodologies, summarizing the prevailing strategies of adaptive/resistance mechanisms in bacterial bioremediation. Further pitfalls and respective future directions are enumerated in invigorating effective bioremediation technologies including overexpression studies and delivery systems. The analysis will aid in abridging the gap for limitations in heavy metal removal strategies and necessary cross-talk in elucidating the complex cascade of events in better bioremediation protocols.

In-vitro biotransformation of tea using tannase produced by Enterobacter cloacae 41.

Tannase is a widely used enzyme that improves the quality of tea by facilitating the release of water-soluble polyphenolic compounds, as well as reduces the formation of tea creams. The microbial tannase enzymes are often employed for tea biotransformation by hydrolyses esters of phenolic acids, including the gallated polyphenols found in blacks teas. The study was focused to investigate the tannase enzyme mediated biotransformation of black tea such as CTC-(Crush, tear, curl) & Kangra orthodox which are commonly used by the south Indian peoples. HPLC spectral analysis revealed that tannase treatment on tea cream formation (CTC & Kangra orthodox tea) allows the hydrolysis of the EGC, GA, ECG, and EGCG. A significant reduction in the formation of tea cream and increased antioxidant activity has been observed in the CTC (1.62 fold) and Kangra orthodox (1.55 fold). The results revealed that tannase treatment helps to improve the quality of black tea infusions with respect to cream formation, the intensity of colour, and sensory characteristics of tea. The result of this study indicates that E. cloacae 41 produced tannase can be used to improve the quality of both tea samples.

Production and functionality of exopolysaccharides in bacteria exposed to a toxic metal environment.

In this study, the production and compositional analysis of exopolysaccharides produced by Bacillus cereus KMS3-1 grown in metal amended conditions were investigated. In addition, the metal adsorption efficacy of exopolysaccharides (EPS) produced by KMS3-1 strain was evaluated in a batch mode. Increased production of exopolysaccharides by KMS3-1 strain was observed while growing under metal amended conditions (100 mg/L) and also, the yield was in the order of Pb(II)>Cu(II)>Cd(II)>Control. Characterization of EPS using FT-IR, XRD, and SEM analysis revealed that the EPS can interact with metal ions through their functional groups (O‒H, CH, CË­O, C‒O, and C‒CË­O) and assist the detoxification process. Further, equilibrium results were fitted with the Langmuir model and notably, the maximum adsorption capacity (Qmax) of EPS for Cd(II), Cu(II), and Pb(II) found to be 54.05, 71.42, and 78.74 mg/g, respectively. To the best of our knowledge, EPS demonstrating proficient metal adsorption was substantiated by XRD analysis in this study. Owing to good adsorbing nature, the exopolysaccharides could be used as chelating substances for wastewater treatment.

Structural characterization, functional and biological activities of an exopolysaccharide produced by probiotic Bacillus licheniformis AG-06 from Indian polyherbal fermented traditional medicine.

An exopolysaccharide (EPS) was purified from the probiotic bacterium Bacillus licheniformis AG-06 isolated from the polyherbal fermented traditional medicine (Ashwagandharishta) of Indian Ayurveda. High-performance liquid chromatography (HPLC) based compositional analysis exhibits the heteropolymeric nature of the EPS consisting of galactose, rhamnose, xylose, mannose, and glucose, as the monomeric units. Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic analyses confirm the presence of typical carbohydrate polymer functional groups and structural units, respectively. The purified EPS demonstrates the web-like fibrous and porous nature in scanning electron microscopic and atomic force microscopic studies. The purified EPS had shown 71.83% and 67.79% of flocculation and emulsification activities, respectively. Antioxidant activity was evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), nitric oxide, and superoxide free radicals and the scavenging actions were increased in a dose-dependent manner. Moreover, the purified EPS exhibits a significant cytotoxic activity against the human lung carcinoma cells (A549), which strongly suggests the anticancer potential of the EPS derived from B. licheniformis AG-06.