Sublethal acetamiprid affects reproduction, development and disrupts gene expression in Binodoxys communis.

At present, understanding of neonicotinoid toxicity in arthropods remains limited. We here evaluated the lethal and sublethal effects of acetamiprid in F0 and F1 generations of Binodoxys communis using a range of sublethal concentrations. The 10% lethal concentration (LC10) and half lethal concentration (LC25) of ACE had negative effects on the B. communis survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonged the duration of the developmental cycle. ACE also had intergenerational effects, with some biological indices affected in the F1 generation after pesticide exposure. Transcriptomic analysis demonstrated that differentially expressed genes were enriched in specific pathways including the amino acid metabolism, carbohydrate metabolism, energy metabolism, exogenous metabolism, signal transduction, and glutathione metabolism pathways. These results indicated strong contact toxicity of ACE to B. communis, which may inhibit their biological control capacity. These results improve our understanding of the toxicological mechanisms of parasitic natural enemies in response to insecticide exposure.

Moderate nitrogen application facilitates Bt cotton growth and suppresses population expansion of aphids (Aphis gossypii) by altering plant physiological characteristics.

Introduction: Excessive application of nitrogen fertilizer in cotton field causes soil and water pollution as well as significant increase of aphid population. Reasonable fertilization is an important approach to improve agricultural production efficiency and reduce agriculture-derived pollutions. This study was aimed to explore the effects of nitrogen fertilizer on the Bt cotton physiological characteristics and the growth and development of A. gossypii, a sap-sucking cotton pest. Methods: Five different levels of Ca(NO3)2 (0.0 g/kg, 0.3 g/kg, 0.9 g/kg, 2.7 g/kg and 8.1 g/kg) were applied into vermiculite as nitrogen fertilizer in order to explore the effects of nitrogen fertilizer on the growth and development of Bt cotton and aphids. Results: The results showed that the medium level of nitrogen fertilizer (0.9 g/kg) effectively facilitated the growth of Bt cotton plant and suppressed the population expansion of aphids, whereas high and extremely high nitrogen application (2.7 and 8.1 g/kg) significantly increased the population size of aphids. Both high and low nitrogen application benefited aphid growth in multiple aspects such as prolonging nymph period and adult lifespan, enhancing fecundity, and improving adult survival rate by elevating soluble sugar content in host Bt cotton plants. Cotton leaf Bt toxin content in medium nitrogen group (0.9 g/kg) was significantly higher than that in high (2.7 and 8.1 g/kg) and low (0.3 g/kg) nitrogen groups, but Bt toxin content in aphids was very low in all the nitrogen treatment groups, suggesting that medium level (0.9 g/kg) might be the optimal nitrogen fertilizer treatment level for promoting cotton seedling growth and inhibiting aphids. Discussion: Overall, this study provides insight into trophic interaction among nitrogen fertilizer levels, Bt cotton, and cotton aphid, and reveals the multiple effects of nitrogen fertilizer levels on growth and development of cotton and aphids. Our findings will contribute to the optimization of the integrated management of Bt cotton and cotton aphids under nitrogen fertilization.

Effects of sublethal fipronil exposure on cross-generational functional responses and gene expression in Binodoxys communis.

The effective systemic insecticide fipronil is widely used on a variety of crops and in public spaces to control insect pests. Binodoxys communis (Gahan) (Hymenoptera: Braconidae) is the dominant natural enemy of Aphis gossypii Glover (Homoptera: Aphididae), an important cotton pest, and has good efficiency in inhibiting aphid populations. The direct effects of environmental residues of sublethal fipronil doses on adult B. communis have not previously been reported. This study therefore aimed to evaluate the side effects and transcriptomic impacts of sublethal fipronil doses on B. communis. The results showed that exposure to the LC10 dose of fipronil significantly reduced the survival rate and parasitism rate of the F0 generation, but did not affect these indicators in the F1 generation. The LC25 dose did not affect the survival or parasitic rates of the F0 generation, but did significantly reduce the survival rate of F1 generation parasitoids. These results indicated that sublethal doses of fipronil affected B. communis population growth. Transcriptome analysis showed that differentially expressed genes (DEGs) in B. communis at 1 h after treatment were primarily enriched in pathways associated with fatty acid elongation, biosynthesis of fatty acids, and fatty acid metabolism. DEGs at 3 days after treatment were mainly enriched in ribosomal functions, glycolysis/gluconeogenesis, and tyrosine metabolism. Six DEGs (PY, ELOVL, VLCOAR, MRJP1, ELOVL AAEL008004-like, and RPL13) were selected for validation with real-time fluorescent quantitative PCR. This is the first report of sublethal, trans-generational, and transcriptomic side effects of fipronil on the dominant parasitoid of A. gossypii. The results of this study show that adaptation of parasitoids to high concentrations of pesticides may be at the expense of their offspring. These findings broaden our overall understanding of the intergenerational adjustments used by insects to respond to pesticide stress and call for risk assessments of the long-term impacts and intergenerational effects of other pesticides.

Biodegradation of pyrene by bacterial consortia: Impact of natural surfactants and iron oxide nanoparticles.

Polycyclic aromatic hydrocarbons (PAHs) are potentially hazardous compounds that could cause a severe impact on many ecosystems. They are very challenging to remove using conventional methods due to their hydrophobic nature. However, this issue can be resolved by utilizing surface-active molecules to increase their bioavailability. In this study, pyrene was chosen as the PAH compound to explore its degradability by the effect of individual bacterial strains (Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3) and mixed consortia (MC) along with natural surfactant derived from Sapindus mukorossi and iron oxide nanoparticles (NPs). Additionally, fatty acids esters, dipeptides, and sugar derivative groups were identified as potent bioactive components of natural surfactants. Various techniques, such as XRD, VSM, TEM, and FE-SEM with EDX, were utilized to characterize the pristine and Fenton-treated iron oxide NPs. The analytical results confirmed that the Fe3O4 crystal phase and spherical-shaped NPs exhibited excellent magnetic properties. The impact of natural surfactants and iron oxide NPs has significantly contributed to the biodegradation process, resulting in a prominent decrease in chemical oxygen demand (COD) levels. Gas chromatography-mass spectrometry (GC-MS) analysis showed that biodegradation systems produced primary hydrocarbon intermediates, which underwent oxidative degradation through Fenton treatment. Interestingly, synthesized iron oxide NPs effectively produced hydroxyl radical (•OH) during the Fenton reaction, which was confirmed by electron paramagnetic resonance (EPR) spectra, and the pristine iron oxide NPs underwent a material transformation observed. The study demonstrated an integrated approach for biodegradation and the Fenton reaction process to enhance the pyrene degradation efficiency (90%) compared to other systems. Using natural surfactants and iron oxide NPs in aquatic environments serves as a crucial platform at the interface of microorganisms and contaminated oil products. This interaction offers a promising solution for PAHs bioremediation.

Enhancement of cell migration and wound healing by nano-herb ointment formulated with biosurfactant, silver nanoparticles and Tridax procumbens.

Introduction: Ointments are generally used as a therapeutic agent for topical medication or transdermal drug delivery, such as wound healing and skin lesions. Methods: In this study, Tridax procumbens plant extract (0.7 g/mL) was used to prepare herbal-infused oil as the oil phase and gelatin-stabilized silver nanoparticle (G-AgNPs) (0.3 g/mL) as the aqueous phase. To blend the oil and aqueous phases, rhamnolipid biosurfactant with a critical micelle concentration of 55 mg/L from strain Pseudomonas aeruginosa PP4 has been used for herb ointment preparation. The average size of the synthesized G-AgNPs was observed between 10-30 nm and confirmed as spherical-shaped particles by TEM analysis. Subsequently, GC-MS and FTIR characterization are used to confirm herb ointment's chemical and functional characteristics. Results: Based on the antibacterial studies, the highest microbial growth inhibition was observed for herb ointment, about 19.5 mm for the pathogen Staphylococcus aureus at the concentration of 100 µg/mL, whereas 15.5 mm was obtained for Escherichia coli, respectively. In addition, the minimum inhibitory concentration (MIC) assay showed negligible bacterial growth at 100 µg/mL for S. aureus and E. coli, respectively. Moreover, the cell viability assay for herb ointment exhibited low cytotoxic activity at higher concentrations (100 µg/mL) in Vero cell lines. In this study, wound scratch assay showed a significant cell migration rate (90 ± 2%) in 3 days of incubation than the control (62 ± 2%). Discussion: As a result, the biosurfactant-based nano-topical herb ointment revealed a low cytotoxic and higher cell migration capacity. Altogether, these findings highlighted the utility of this herb ointment in therapeutic applications such as wound healing.

Detection of Neonicotinoids in agriculture soil and degradation of thiacloprid through photo degradation, biodegradation and photo-biodegradation.

The social and ecological influence of Neonicotinoids (NEOs) usage in agriculture sector is progressively higher. There are seven NEOs insecticides widely used for the insects control. Among the NEOs, thiacloprid (THD) was extensively used for insect control during crop cultivation. This study targets to analyse the contamination levels of NEOs in agricultural soil and identify photo-biodegradation of THD degradation using pure isolates and mixed consortium. The photo degradation (PD), biodegradation (BD) and photo-biodegradation (PBD) of THD were compared. The corn field agricultural soils were polluted by four NEOs, among them THD had greater contamination level (surface soil: 3901.2 ± 0.04 µg/g) and (sub-surface soil: 3988.6 ± 0.05 µg/g). Three soil free enriched bacterial strains following Bacillus atrophaeus (PB-2), Priestia megaterium (PB-3) (formerly known as Bacillus megaterium), and Peribacillus simplex (PB-4) (formerly known as Bacillus simplex) were identified by microbiological and molecular 16s rRNA gene sequencing. The PD, BD and PBD of THD were conducted and degradation rate was detected by instrument UPLC-MS-MS. The PBD process with blue-LEDs showed better THD degradation efficiency than PD and BD, where the specific THD degradation rate was 85 ± 0.2%, 87 ± 0.5%, and 89 ± 0.3%, respectively for PB-2, PB-3 and PB-4. Then, the photo-biodegradation performance is greater at 150, 175, 200 rpm, pH 7.0-9.0, and temperature 30-35 °C. After the PBD system deliver four intermediate metabolites, the THD degradation process maybe through nitro reduction, hydroxylation and oxidative cleavage pathway.

Impact of biosurfactant and iron nanoparticles on biodegradation of polyaromatic hydrocarbons (PAHs).

Polycyclic aromatic hydrocarbons (PAHs) are hazardous toxic contaminants and considered as primary pollutants due to their persistent nature and most of them are carcinogenic and mutagenic. The key challenge in PAHs degradation is their hydrophobic nature, which makes them one of the most complex materials and inaccessible by a broad range of microorganisms. This bioavailability can be increased by using a biosurfactant. In the present study mixed PAHs were degraded using the biosurfactant producing bacterial strains. In addition, iron nanoparticles were synthesized and the impact of iron nanoparticles on the growth of the mixed bacterial strains (Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3) was optimized. The mixed PAHs (anthracene, pyrene, and benzo(a)pyrene) degradation was enhanced by addition of biosurfactant (produced by Bacillus subtilis A1) and iron nanoparticles, resulting in 85% of degradation efficiency. The addition of the biosurfactant increased the bioavailability of the PAHs in the aqueous environment, which might help bacterial cells for the initial settlement and development. The addition of iron nanoparticles increased both bacterial biomass and PAHs adsorption over their surface. These overall interactions assisted in the utilization of PAHs by the mixed bacterial consortia. This study illustrates that this integrated approach can be elaborated for the removal of the complex PAHs pollutants from soil and aqueous environments.

Enhanced biodegradation of hydrophobic organic pollutants by the bacterial consortium: Impact of enzymes and biosurfactants.

Hydrocarbons and their derivative compounds are recalcitrant in nature and causing adverse impacts to the environment and are classified as important pollutants. Removal of these pollutants from the atmosphere is a challenging process. Hydrophobic organic pollutants (HOPs) including crude oil, diesel, dotriacontane (C32), and tetracontane (C40) are subjected to the biodegradation study by using a bacterial consortium consist of Bacillus subtilis, Pseudomonas stutzeri, and Acinetobacter baumannii. The impact of pH and temperature on the biodegradation process was monitored. During the HOPs biodegradation, the impact of hydrocarbon-degrading extracellular enzymes such as alcohol dehydrogenase, alkane hydroxylase, and lipase was examined, and found average activity about 47.2, 44.3, and 51.8 µmol/mg-1, respectively. Additionally, other enzymes such as catechol 1,2 dioxygenase and catechol 2,3 dioxygenase were found as 118 and 112 µmol/mg-1 Enzyme as an average range in all the HOPs degradation, respectively. Also, the impact of the extracellular polymeric substance and proteins were elucidated during the biodegradation of HOPs with the average range of 116.90, 54.98 mg/L-1 respectively. The impact of biosurfactants on the degradation of different types of HOPs is elucidated. Very slight changes in the pH were also noticed during the biodegradation study. Biodegradation efficiency was calculated as 90, 84, 76, and 72% for crude oil, diesel, C32, and C40, respectively. Changes in the major functional groups (CH, C-O-C, CO, =CH2, CH2, CH3) were confirmed by FTIR analysis and intermediated metabolites were identified by GCMS analysis. The surface-active molecules along with the enzymes played a crucial role in the biodegradation process.

Characterization of crude oil degrading bacterial communities and their impact on biofilm formation.

In the present study, produced water sample collected from the Indian crude oil reservoir is used to enrich the bacterial communities. The impact of these enriched bacterial communities on the biodegradation of crude oil, biofilm formation, and biocorrosion process are elucidated. A crude oil degradation study is carried out with the minimal salt medium and 94% of crude oil was utilized by enriched bacterial communities. During the crude oil degradation many enzymes including alkane hydroxylase, alcohol dehydrogenase, and lipase are playing a key role in the biodegradation processes. The role of enriched bacterial biofilm on biocorrosion reactions are monitored by weight loss studies and electrochemical analysis. Weight loss study revealed that the biotic system has vigorous corrosion attacks compared to the abiotic system. Both AC-Impedance and Tafel analysis confirmed that the nature of the corrosion reaction take place in the biotic system. Very less charge transfer resistance and higher corrosion current are observed in the biotic system than in the abiotic system. Scanning electron microscope confirms that the dense biofilm formation favoured the pitting type of corrosion. X-ray diffraction analysis confirms that the metal oxides formed in the corrosion systems (biotic). From the metagenomic analysis of the V3-V4 region revealed that presence of diverse bacterial communities in the biofilm, and most of them are uncultured/unknown. Among the known genus, Bacillus, Halomonas, etc are dominant in the enriched bacterial biofilm sample. From this study, we conclude that the uncultured bacterial strains are found to be playing a key role in the pitting type of corrosion and they can utilize crude oil hydrocarbons, which make them succeeded in extreme oil reservoir environments.

Photo-biodegradation of imidacloprid under blue light-emitting diodes with bacteria and co-metabolic regulation.

Imidacloprid (IMI) is existence in the soil environment with a half-life habitually more than hundred days. This study targets to determine, identify and characterize photo-biodegradation bacteria from neonicotinoids (NEOs) contaminated agricultural field soils. The sub-surface soil had a higher level contamination of NEOs, in specifically greater concentration of IMI (3445.2 ± 0.09 µg/g) and thiacloprid (4084.4 ± 0.09 µg/g) has been found. Three bacteria Ralstonia pickettii (PBMS-2), Bacillus cereus (PBMS-3) and Shinella zoogloeoides (PBMS-4) was identified from soil-free stable enrichment cultures. The biodegradability of IMI (50 mg L-1) by three bacteria under different colors of light-emitting diodes (LEDs) with a constant 12 V power supply was tested and found that the blue-LEDs had greatest efficiency in supporting biodegradation of IMI which is called photo-biodegradation. In specific, the rate of photo-biodegradation of IMI by Ralstonia pickettii (87%), Bacillus cereus (80%) and Shinella zoogloeoides (80%) was measured. Besides this study also tested the effect of aeration (rpm), pH, and temperature on photo-biodegradation of IMI. There were seven intermediate metabolites were measured as biodegradation products of IMI under photo-biodegradation conditions and they are; IMI-urea, IMI-desnitro, 6-chloronicotinic acid, 6-hydroxy nicotinic acid, IMI- aminoguanidine, IMI-nitrosoguanidine and 4,5-hydroxy IMI, these metabolites are may non-toxic to the environment.

Bacterial community analysis of biofilm on API 5LX carbon steel in an oil reservoir environment.

This study aimed to characterize the biofilm microbial community that causes corrosion of API 5LX carbon steel. API 5LX carbon steel coupons were incubated with raw produced water collected from two oil reservoir stations or filter-sterilized produced water. Biofilm 16S rRNA amplicon sequencing revealed that the bacterial community present in the biofilm was dominated by Proteobacteria, including Marinobacter hydrocarbonoclaustics and Marinobacter alkaliphilus. Electrochemical analysis such as impedance and polarization results indicated that Proteobacteria biofilm accelerated corrosion by ~ twofold (2.1 ± 0.61 mm/years) or ~ fourfold (~ 3.7 ± 0.42 mm/years) when compared to the control treatment (0.95 ± 0.1 mm/years). Scanning electron and atomic force microscopy revealed the presence of a thick biofilm and pitting corrosion. X-ray diffraction revealed higher amounts of the corrosion products Fe2O3, γ-FeOOH, and α-FeOOH, and confirmed that the microbial biofilm strongly oxidized the iron and contributed to the acceleration of corrosion of carbon metal API 5LX.

Heterogeneous electro-Fenton using three-dimension NZVI-BC electrodes for degradation of neonicotinoid wastewater.

Neonicotinoids (NEOs), as the most widely used pesticides, pose a serious threat to water ecosystems, especially clothianidin (CLO). However, the degradation behavior of CLO, as a new type of persistent organic pollutant, is rarely studied in wastewater treatment. To bridge this gap, heterogeneous electro-Fenton system using three-dimension electrodes made of biochar-supported zero-valent iron nanoparticle hybrid material (NZVI-BC), abbreviated as 3D-ICE-EF system, is invented and initially applied in CLO wastewater degradation, without the addition of Fenton reagent. NZVI-BC in 3D-ICE-EF system can concentrate CLO on electrodes by excellent adsorption and effectively eliminate it to achieve self-cleaning effect. In addition, the deposition of iron mud (Fe(OH)3) and the circular utilization of Fe in Fenton system is effectively improved by the addition of hydroquinone (HQ) in 3D-ICE-EF system. The pH applicable scope of Fenton system is extended to alkaline condition by the applications of NZVI-BC electrodes. The increase in the acidity of electrolyte is considered the primary reason of the high degradation efficiency of CLO in 3D-ICE-EF system at an initial pH of 9.0. The degradation performance of 3D-ICE-EF system tends to be promoted by the increase of current intensity and air flow rate. Seven plausible mechanisms of CLO degradation were identified in 3D-ICE-EF system. The ecotoxicity evaluation of degradation products indicated that CLO degradation in 3D-ICE-EF system exhibits a remarkable tendency to reduce toxicity levels.

Agricultural waste materials enhance protease production by Bacillus subtilis B22 in submerged fermentation under blue light-emitting diodes.

Bacillus bacteria have major utility in large-scale production of industrial enzymes, among which proteases have particular importance. B. subtilis B22, an aerobic and chemotrophic strain, was isolated from kimchi and identified by 16S rRNA gene sequencing. Extracellular protease production was determined in basic medium, with 1% (w/v) casein as substrate, by submerged fermentation at 37 °C under blue, green, red and white light-emitting diodes (LEDs), white fluorescent light and darkness. Fermentation under blue LEDs maximized protease production (110.79 ± 1.8 U/mL at 24 h). Various agricultural waste products enhanced production and groundnut oil cake yielded the most protease (334 ± 1.8 U/mL at 72 h). Activity and stability of the purified protease were optimum at pH 7-10 and 20-60 °C. Activity increased in the presence of Ca2+, Mg2+ and Mn2+, while Fe2+, Zn2+, Co2+ and Cu2+ moderated activity, and Ni2+ and Hg2+ inhibited activity. Activity was high (98%) in the presence of ethylenediaminetetraacetic acid (EDTA) but inhibited by phenylmethanesulfonyl fluoride (PMSF). The protease was unaffected by nonionic surfactants, tolerated an anionic surfactant and oxidizing agents, and was compatible with multiple organic solvents. These properties suggest utility of protease produced by B. subtilis B22 under blue LEDs for industrial applications.

Role of thermophilic bacteria (Bacillus and Geobacillus) on crude oil degradation and biocorrosion in oil reservoir environment.

Thermophilic bacterial communities generate thick biofilm on carbon steel API 5LX and produce extracellular metabolic products to accelerate the corrosion process in oil reservoirs. In the present study, nine thermophilic biocorrosive bacterial strains belonging to Bacillus and Geobacillus were isolated from the crude oil and produced water sample, and identified using 16S rRNA gene sequencing. The biodegradation efficiency of hydrocarbons was found to be high in the presence of bacterial isolates MN6 (82%), IR4 (94%) and IR2 (87%). During the biodegradation process, induction of the catabolic enzymes such as alkane hydroxylase, alcohol dehydrogenase and lipase were also examined in these isolates. Among them, the highest activity of alkane hydroxylase (130 µmol mg-1 protein) in IR4, alcohol dehydrogenase (70 µmol mg-1 protein) in IR2, and higher lipase activity in IR4 (60 µmol mg-1 protein) was observed. Electrochemical impedance spectroscopy and X-ray diffraction data showed that these isolates oxidize iron into ferrous/ferric oxides as the corrosion products on the carbon steel surface, whilst the crude oil hydrocarbon served as a sole carbon source for bacterial growth and development in such extreme environments.

Role of 2-mercaptopyridine on control of microbial influenced corrosion of copper CW024A metal in cooling water system.

In this present study, the biocorrosion behaviour of Bacillus thuringiensis EN2 and B. oleronius EN9 on copper metal CW024A (Cu) in cooling water system (1% chloride) were evaluated using weight loss, electrochemical impedance spectroscopy (EIS) and surface analysis. In presence of EN2 and EN9, the corrosion rates (CR) were higher, about 0.021 mm/y and 0.032 mm/y than control system (0.004 mm/y). On the other hand, the presence of corrosion inhibitor 2-mercaptopyridine (2-MCP) with bacteria (EN2 and EN9), the biofilm on metal surface was highly inhibited and thus reduces the corrosion rate (CR: 0.004 mm/y). The electrochemical behaviour of CW024A metal was correlated with the adsorbed corrosion inhibitor film and biofilm. Atomic force microscopy (AFM) analysis revealed that the presence of EN2 and EN9 more pits was observed on the metal surface rather than 2-MCP system. EIS confirms the inhibitor act as cathodic type of inhibitor and thus leads to the inhibition of CR. Overall, this work concluded that corrosion inhibitor (2-MCP) inhibits, the bacterial biofilm formation on the metal surface due to the formation of productive layer on metal surface as coordination of NH bond. Which leads to the reduction of bacterial attachment and thus higher corrosion inhibition efficiency (75%) obtained. This is the first work disclosing the role of 2-MCP formulations as potent anti-bacterial and corrosion inhibition efficiency on copper metal in cooling water tower environment.

Enhanced amylase production by a Bacillus subtilis strain under blue light-emitting diodes.

A chemotrophic, aerobic bacterial strain, Bacillus subtilis B2, was used to produce amylase by submerged fermentation under different light sources. SDS-PAGE indicated that the 55 kDa enzyme belonged to the α-amylase group. B2 was incubated in basal media with 1% soluble starch (pH 7.0) under blue, green, red, and white light-emitting diodes (LEDs), and white fluorescent light. Fermentation under blue LEDs maximized amylase production (180.59 ± 1.6 U/mL at 24 h). Production at 48 h increased to 310.56 ± 1.6 U/mL with 5% glucose as a simple carbon source and to 300.51 ± 1.7 U/mL with 5% groundnut oil cake as an agricultural waste substrate. Activity and stability of the amylase were greatest at pH 7.0 and 45-55 °C. Na+, Ca2+, Mg2+, Co2+, Ba2+, and K+ increased activity, while Ni2+, Hg2+, Mn2+, Cu2+, Fe3+, and Zn2+ inhibited activity. EDTA, PMSF and DTNB reduced activity by 50% or more, while tetrafluoroethylene and 1,10-phenanthroline reduced activity by 30%. The amylase was highly tolerant of the surfactants, compatible with organic solvents, oxidizing agents and the reducing agents reduced activity. These properties suggest utility of amylase produced by B. subtilis B2 under blue LED-mediated fermentation for industrial applications.

Red yeast rice fermentation with Bacillus subtilis B2 under blue light-emitting diodes increases antioxidant secondary products (Manuscript ID: BPBSE-18-0387).

Light and bacteria can be used in combination to enhance secondary metabolite production during fermentation. Red yeast rice powder (RYRP) was inoculated with Bacillus subtilis (B2) isolated from freshwater seafood and incubated under light-emitting diodes (LEDs) of different colors (blue, green, red, white), fluorescent white light, and in darkness. Blue LED-mediated fermentation with B2 significantly enhanced production of phenolic compounds (68.4 ± 1 mg GAE/g DW) and flavonoids (51.7 ± 1 mg QE/g DW) compared to white light and darkness. Total antioxidant activity of RYRP extract after fermentation with B2 was > 77%; hydroxyl radical and superoxide scavenging were > 66%. DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) and ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)) radical scavenging activities were 51% and > 67%, respectively. Reducing power was approximately twice that of extract from RYRP without B2. FTIR analysis showed a high content of hydroxyl, nitrile and carboxylic groups in the extract. Derivatives of cinnamic, benzoic and phophinodithioic acid, and quinazolinone were identified by GC-MS. Findings show that fermenting RYRP with B. subtilis B2 under blue LEDs enhances production of secondary metabolites, which should have applications in industrial fermentation processes.

Biosurfactant and enzyme mediated crude oil degradation by Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3.

The present study focuses on the optimization of biosurfactant (BS) production using two potential biosurfactant producer Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3 and role of enzymes in the biodegradation of crude oil. The optimal conditions for P. stutzeri NA3 and A. baumannii MN3 for biodegradation were pH of 8 and 7; temperature of 30 and 40 °C, respectively. P. stutzeri NA3 and A. baumannii MN3 produced 3.81 and 4.68 g/L of BS, respectively. Gas chromatography mass spectrometry confirmed that BS was mainly composed of fatty acids. Furthermore, the role of the degradative enzymes, alkane hydroxylase, alcohol dehydrogenase and laccase on biodegradation of crude oil are explained. Maximum biodegradation efficiency (BE) was recorded for mixed consortia (86%) followed by strain P. stutzeri NA3 (84%). Both bacterial strains were found to be vigorous biodegraders of crude oil than other biosurfactant-producing bacteria due to their enzyme production capabilities and our results suggests that the bacterial isolates can be used for effective degradation of crude oil within short time periods.

Enzyme-mediated biodegradation of long-chain n-alkanes (C32 and C40) by thermophilic bacteria.

Removal of long-chain hydrocarbons and n-alkanes from oil-contaminated environments are mere important to reduce the ecological damages, while bio-augmentation is a very promising technology that requires highly efficient microbes. In present study, the efficiency of pure isolates, i.e., Geobacillus thermoparaffinivorans IR2, Geobacillus stearothermophillus IR4 and Bacillus licheniformis MN6 and mixed consortium on degradation of long-chain n-alkanes C32 and C40 was investigated by batch cultivation test. Biodegradation efficiencies were found high for C32 by mixed consortium (90%) than pure strains, while the pure strains were better in degradation of C40 than mixed consortium (87%). In contrast, the maximum alkane hydroxylase activities (161 µmol mg-1 protein) were recorded in mixed consortium system that had supplied with C40 as sole carbon source. Also, the alcohol dehydrogenase (71 µmol mg-1 protein) and lipase activity (57 µmol mg-1 protein) were found high. Along with the enzyme activities, the hydrophobicity natures of the bacterial strains were found to determine the degradation efficiency of the hydrocarbons. Thus, the study suggested that the hydrophobicity of the bacteria is a critical parameter to understand the biodegradation of n-alkanes.

Airborne bacteria associated with corrosion of mild steel 1010 and aluminum alloy 1100.

A novel approach to measure the contribution of airborne bacteria on corrosion effects of mild steel (MS) and aluminum alloy (AA) as a function of their exposure period, and the atmospheric chemical composition was investigated at an urban industrial coastal site, Singapore. The 16S rRNA and phylogenetic analyses showed that Firmicutes are the predominant bacteria detected in AA and MS samples. The dominant bacterial groups identified were Bacillaceae, Staphylococcaceae, and Paenibacillaceae. The growth and proliferation of these bacteria could be due to the presence of humidity and chemical pollutants in the atmosphere, leading to corrosion. Weight loss showed stronger corrosion resistance of AA (1.37 mg/cm2) than MS (26.13 mg/cm2) over the exposure period of 150 days. The higher corrosion rate could be a result of simultaneous action of pollutants and bacterial exopolysaccharides on the metal surfaces. This study demonstrates the significant involvement of airborne bacteria on atmospheric corrosion of engineering materials.