Characterization of thermophilic halotolerant Aeribacillus pallidus TD1 from Tao Dam Hot Spring, Thailand

Competitive mechanism of salt-tolerance/degradation-performance of organic pollutant in bacteria: Na+/H+ antiporters contribute to salt-stress resistance but impact phenol degradation

Phenolic-laden wastewater is typically characterized by its high toxicity and high salinity, imposing serious limits on the application of bioremediation. Although a few halotolerant microorganisms have been reported to degrade phenol, their removal efficiency on high concentrations of phenol remains unsatisfactory. What's more, the deep interaction molecular mechanism of salt-tolerance/phenol-degradation performance has not been clearly revealed. Here, a halotolerant strain Aeribacillus pallidus W-12 employed a meta-pathway to efficiently degrade high concentration of phenol even under high salinity conditions. Investigation of salt-tolerance strategy indicated that four Na+/H+ antiporters, which are widely distributed in bacteria, synergistically endowed the strain with excellent salt adaptability. All these antiporters differentially but positively responded to salinity changes and induction of phenol, forming a synergistic transport effect on salt ions and phenol. In-depth analysis revealed a competitive relationship between salt tolerance and degradation performance, which significantly impaired the degradation efficiency at relatively high salinity. The efficient degradation performance of W-12 under different phenol concentrations and salinity conditions indicated its bioremediation potential for multiple types of phenolic wastewater. Collectively, the competitive mechanism of salt tolerance and degradation performance enlightens a new strategy of introducing or re-constructing Na+/H+ antiporters to further improve bioremediation efficiency of hypersaline organic wastewater.

Draft genome sequences of two thermophilic, spore-forming Aeribacillus pallidus strains isolated from dairy products

The presence of thermophilic spore-forming bacteria is challenging in industrial food processing. The presented genome sequences of Aeribacillus pallidus, isolated from raw milk and cocoa powder, provide insights into how to prevent damage to minimally processed foods and products with extended shelf life, such as milk products.

Effects of parasitism by a parasitoid wasp on the gut microbiota in a predaceous lady beetle host

BACKGROUND

The gut microbiota has an intimate relationship with insect hosts and this relationship can become complicated with parasitic organisms being involved with the host. To date there has been limited evidence for the relevance of parasitism of the host by parasitoids to host gut microbiota, especially in host insect predators. Here, our study examined gut microbiotas in larvae of the predaceous lady beetle, Coccinella septempunctata, in response to their parasitism by Homalotylus eytelweinii regarding the development progress of offspring parasitoids.

RESULTS

Overall 58.5% of gut bacterial operational taxonomic units (OTUs) in the parasitized lady beetle were different from those in the unparasitized host. The phylum Proteobacteria abundance increased while Firmicutes decreased in parasitized hosts compared to the unparasitized. The abundance of genus Aeribacillus decreased substantially in the parasitized lady beetle across all stages of the offspring development compared to the unparasitized host. The α-diversity of the gut microbiota in a parasitized lady beetle larva increased at the early stage of offspring parasitoids and then returned over the intermediate and later stages. Analyses of β-diversity indicated that the gut microbial community in a parasitized lady beetle was distinct from that in an unparasitized one and different between early or middle and late stages of offspring parasitoids in parasitized hosts.

CONCLUSION

Our results provide evidence for the relevance of the gut microbiota to interactions between a lady beetle host and its parasitoid. Our study provides a starting point for further investigations of the role the gut microbiota may play in host-parasitoid interactions. © 2023 Society of Chemical Industry.

Bacillales: From Taxonomy to Biotechnological and Industrial Perspectives

For a long time, the genus Bacillus has been known and considered among the most applicable genera in several fields. Recent taxonomical developments resulted in the identification of more species in Bacillus-related genera, particularly in the order Bacillales (earlier heterotypic synonym: Caryophanales), with potential application for biotechnological and industrial purposes such as biofuels, bioactive agents, biopolymers, and enzymes. Therefore, a thorough understanding of the taxonomy, growth requirements and physiology, genomics, and metabolic pathways in the highly diverse bacterial order, Bacillales, will facilitate a more robust designing and sustainable production of strain lines relevant to a circular economy. This paper is focused principally on less-known genera and their potential in the order Bacillales for promising applications in the industry and addresses the taxonomical complexities of this order. Moreover, it emphasizes the biotechnological usage of some engineered strains of the order Bacillales. The elucidation of novel taxa, their metabolic pathways, and growth conditions would make it possible to drive industrial processes toward an upgraded functionality based on the microbial nature.

Elucidating biofouling over thermal and spatial gradients in seawater membrane distillation in hot climatic conditions

Biofouling is a hurdle of seawater desalination that increases water costs and energy consumption. In membrane distillation (MD), biofouling development is complicated due to the temperature effect that adversely affects microbial growth. Given the high relevance of MD to regions with abundant warm seawater, it is essential to explore the biofouling propensity of microbial communities with higher tolerance to elevated temperature conditions. This study presents a comprehensive analysis of the spatial and temporal biofilm distribution and associated membrane fouling during direct contact MD (DCMD) of the Red Sea water. We found that structure and composition of the biofilm layer played a significant role in the extent of permeate flux decline, and biofilms that built up at 45°C had lower bacterial concentration but higher extracellular polymeric substances (EPS) content as compared to biofilms that formed at 55 °C and 65°C. Pore wetting and bacterial passage to the permeate side were initially observed but slowed down as operating time increased. Intact cells in biofilms dominated over the damaged cells at any tested condition emphasizing the high adaptivity of the Red Sea microbial communities to elevated feed temperatures. A comparison of microbial abundance revealed a difference in bacterial distribution between the feed and biofilm samples. A shift in the biofilm microbial community and colonization of the membrane surface with thermophilic bacteria with the feed temperature increase was observed. The results of this study improve our understanding of biofouling propensity in MD that utilizes temperature-resilient feed waters.

Effect of Temperature on Acetate Mineralization Kinetics and Microbial Community Composition in a Hydrocarbon-Affected Microbial Community During a Shift From Oxic to Sulfidogenic Conditions

Aquifer thermal energy storage (ATES) allows for the seasonal storage and extraction of heat in the subsurface thus reducing reliance on fossil fuels and supporting decarbonization of the heating and cooling sector. However, the impacts of higher temperatures toward biodiversity and ecosystem services in the subsurface environment remain unclear. Here, we conducted a laboratory microcosm study comprising a hydrocarbon-degrading microbial community from a sulfidic hydrocarbon-contaminated aquifer spiked with ¹³C-labeled acetate and incubated at temperatures between 12 and 80°C to evaluate (i) the extent and rates of acetate mineralization and (ii) the resultant temperature-induced shifts in the microbial community structure. We observed biphasic mineralization curves at 12, 25, 38, and 45°C, arising from immediate and fast aerobic mineralization due to an initial oxygen exposure, followed by slower mineralization at sulfidogenic conditions. At 60°C and several replicates at 45°C, acetate was only aerobically mineralized. At 80°C, no mineralization was observed within 178 days. Rates of acetate mineralization coupled to sulfate reduction at 25 and 38°C were six times faster than at 12°C. Distinct microbial communities developed in oxic and strictly anoxic phases of mineralization as well as at different temperatures. Members of the Alphaproteobacteria were dominant in the oxic mineralization phase at 12–38°C, succeeded by a more diverse community in the anoxic phase composed of Deltaproteobacteria, Clostridia, Spirochaetia, Gammaproteobacteria and Anaerolinea, with varying abundances dependent on the temperature. In the oxic phases at 45 and 60°C, phylotypes affiliated to spore-forming Bacilli developed. In conclusion, temperatures up to 38°C allowed aerobic and anaerobic acetate mineralization albeit at varying rates, while mineralization occurred mainly aerobically between 45 and 60°C; thermophilic sulfate reducers being active at temperatures > 45°C were not detected. Hence, temperature may affect dissolved organic carbon mineralization rates in ATES while the variability in the microbial community composition during the transition from micro-oxic to sulfidogenic conditions highlights the crucial role of electron acceptor availability when combining ATES with bioremediation.

Purification and characterization of a noble thermostable algal starch liquefying alpha-amylase from Aeribacillus pallidus BTPS-2 isolated from geothermal spring of Nepal

A thermophilic strain, Aeribacillus pallidus BTPS-2 was isolated from Bhurung geothermal spring of Nepal. The 16 s rRNA sequence showed 99.8 % similarity with the type strain Aeribacillus pallidus DSM 3670. The morphological, physiological and biochemical properties were similar to the type strain. Alpha-amylase from A. pallidus BTPS-2 was purified to 19-fold purification by DEAE-Cellulose ion exchange chromatography. The K_m value of amylase on starch was 0.51 ± 0.05 mg/mL. The optimum pH and temperature were 7.0 and 70 °C. SDS-PAGE analysis showed a single band at 100 kDa. The half-life of the enzyme at 80 °C was 2.81 h. The enzyme showed an inhibitory effect in the presence of Fe²⁺, Pb²⁺, Sn²⁺ and Hg²⁺ at 10 mM concentrations. TLC analysis showed that the enzyme is a liquifying alpha-amylase. The enzyme reduced the viscosity of algal biomass suspension up to 74.2 ± 0.17 % which was more efficient than Bacillus amyloliquefaciens alpha-amylase (80.5 ± 0.2 %).

Biodegradation of aliphatic and polycyclic aromatic hydrocarbons by the thermophilic bioemulsifier-producing Aeribacillus pallidus strain SL-1

The utilization of thermophilic hydrocarbon-degrading microorganisms is a suitable strategy for improving biodegradation of petroleum hydrocarbons and PAHs, as well as enhancing oil recovery from high-temperature reservoirs. In this study, the thermophilic strain Aeribacillus pallidus SL-1 was evaluated for the biodegradation of crude oil and PAHs at 60 °C. Strain SL-1 was found to preferentially degrade short-chain n-alkanes (<C17) and aromatic hydrocarbons from crude oil. The highest degradation rate of 84% was obtained with 1000 mg/l naphthalene as sole carbon source. Additionally, the strain was able to degrade 80% of phenanthrene (200 mg/l) and 50% of pyrene (50 mg/l) within 5 days at 60 °C. The SL-bioemulsifier produced by strain SL-1 was identified as a glycoprotein with stable emulsifying activity over a wide range of environmental conditions. Chemical composition studies exhibited that the SL-bioemulsifier consisted of polysaccharides (65.6%) and proteins (13.1%), among them, proteins were the major emulsifying functional substrates. Furthermore, the SL-bioemulsifier was able to enhance the solubility of PAHs. Thus, the bioemulsifier-producing strain SL-1 has great potential for applications in high-temperature bioremediation.

Draft Genome Sequence of Thermophilic Halotolerant Aeribacillus pallidus TD1, Isolated from Tao Dam Hot Spring, Thailand

Aeribacillus pallidus TD1 is a thermophilic bacterium isolated from a hot spring in Thailand. The genome sequence of A. pallidus TD1 contains a gene-encoded naphthalene dioxygenase, which is a key enzyme for naphthalene degradation.

Aeribacillus pallidus TD1 is a thermophilic bacterium isolated from a hot spring in Thailand. The genome sequence of A. pallidus TD1 contains a gene-encoded naphthalene dioxygenase, which is a key enzyme for naphthalene degradation. This 3.7-Mb draft genome sequence of A. pallidus TD1 will contribute to the understanding of polycyclic aromatic hydrocarbon (PAH) degradation in high-temperature environments.

Genome Sequence of Aeribacillus pallidus W-12, a Thermophilic Bacterium Containing Possible Biodesulfurization and Biodenitrification Pathways

Aeribacillus pallidus W-12 is a thermophilic bacterium isolated from Dagang oil reservoir sewage in northern China. The genome sequence of this strain reported here may provide insights into genomic characteristics regarding the biodegradation of organosulfur and organic nitrogen compounds under elevated temperature.

Purification and biochemical characterization of a novel thermostable serine alkaline protease from Aeribacillus pallidus C10: a potential additive for detergents

An extracellular thermostable alkaline serine protease enzyme from Aeribacillus pallidus C10 (GenBank No: KC333049), was purified 4.85 and 17. 32-fold with a yield of 26.9 and 19.56%, respectively, through DE52 anion exchange and Probond affinity chromatography. The molecular mass of the enzyme was determined through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), with approximately 38.35 kDa. The enzyme exhibited optimum activity at pH 9 and at temperature 60 °C. It was determined that the enzyme had remained stable at the range of pH 7.0-10.0, and that it had preserved more than 80% of its activity at a broad temperature range (20-80 °C). The enzyme activity was found to retain more than 70% and 55% in the presence of organic solvents and commercial detergents, respectively. In addition, it was observed that the enzyme activity had increased in the presence of 5% SDS. KM and Vmax values were calculated as 0.197 mg/mL and 7.29 μmol.mL-1.min-1, respectively.

Biofilm characteristics and evaluation of the sanitation procedures of thermophilic Aeribacillus pallidus E334 biofilms

The ability of Aeribacillus pallidus E334 to produce pellicle and form a biofilm was studied. Optimal biofilm formation occurred at 60 °C, pH 7.5 and 1.5% NaCl. Extra polymeric substances (EPS) were composed of proteins and eDNA (21.4 kb). E334 formed biofilm on many surfaces, but mostly preferred polypropylene and glass. Using CLSM analysis, the network-like structure of the EPS was observed. The A. pallidus biofilm had a novel eDNA content. DNaseI susceptibility (86.8% removal) of eDNA revealed its importance in mature biofilms, but the purified eDNA was resistant to DNaseI, probably due to its extended folding outside the matrix. Among 15 cleaning agents, biofilms could be removed with alkaline protease and sodium dodecyl sulphate (SDS). The removal of cells from polypropylene and biomass on glass was achieved with combined SDS/alkaline protease treatment. Strong A. pallidus biofilms could cause risks for industrial processes and abiotic surfaces must be taken into consideration in terms of sanitation procedures.

Development of an immunoFET biosensor for the detection of biotinylated PCR product

ImmunoFET (IMFET) biosensor is a simple platform for the detection of biotinylated products of polymerase chain reaction (PCR). Construction of the IMFET biosensor started with adsorption of 1.5 mg/mL of protein A (PA) onto the insulated gate surface of ISFET for 90 min. Next, the immobilized 1/500 dilution of anti-biotin antibody was adsorbed onto the PA layer for 60 min. The IMFET biosensor was subsequently ready for detection of the biotinylated amplicon. The IMFET biosensor showed highly specific binding to the biotinylated PCR product of the phaE gene of Haloquadratum walsbyi DSM 16854. The phaE gene is a biomarker of polyhydroxyalkanoate (PHA) producers that contain PHA synthase class III. The lowest amount of DNA template of H. walsbyi DSM 16854 that the IMFET biosensor could detect was 125 fg. The IMFET biosensor has a lower amount of detection compared with a DNA lateral flow biosensor from our previous study. The degree of linearity of the biosensor signal was influenced by the concentration of the biotinylated amplicon. The IMFET biosensor also has a short response time (approximately 30 times) to detect the phaE amplicon compared to an agarose gel electrophoresis. The IMFET biosensor is a promising tool for the detection of the biotinylated PCR product, and it can be integrated into a micro total analysis system (μTAS).

Draft Genome Sequence of Aeribacillus pallidus Strain 8m3, a Thermophilic Hydrocarbon-Oxidizing Bacterium Isolated from the Dagang Oil Field (China)

The draft genome sequence of Aeribacillus pallidus strain 8m3, a thermophilic aerobic oil-oxidizing bacterium isolated from production water from the Dagang high-temperature oil field, China, is presented here. The genome is annotated to provide insights into the genomic and phenotypic diversity of the genus Aeribacillus.

Suitability of the alkalistable carbonic anhydrase from a polyextremophilic bacterium Aeribacillus pallidus TSHB1 in biomimetic carbon sequestration

Carbonic anhydrase (CA) was produced from the polyextremophilic (halotolerant, moderately thermophilic and alkaliphilic) bacterium Aeribacillus pallidus TSHB1 isolated from water and sediment samples of Choti Anhoni hot spring of Pipariya, Madhya Pradesh (India), is being reported to be suitable for carbon sequestration. Growth and CA production were inhibited at higher CO2 concentration (5-10 %). Under optimized culture variables (tryptone 0.8 %, yeast extract 0.08 %, glucose 1 %, micronutrient solution 1 %, inoculums size 1.10 %, agitation 200 at pH 8, and temperature 55 °C), 3.7-fold higher CA production was attained than that under unoptimized conditions. The zymogram analysis of the partially purified CA revealed an activity band corresponding to 32 kDa. The enzyme is stable in the pH range between 8.0 and 11.0 with T 1/2 of 40, 15, and 8 min at 60, 70, and 80 °C, respectively. The CA of A. pallidus displayed a marked enhancement in the rate of CaCO3 precipitation from aqueous CO2. The CA-aided formation of CaCO3 was 42.5 mg mg(-1) protein. Scanning electron microscopy revealed the formation of rhomboid calcite crystals. This is the first report on the production and applicability of CA from the polyextremophilic A. pallidus in carbon sequestration.

Production and characterization of a new antibacterial peptide obtained from Aeribacillus pallidus SAT4

A novel thermophilic bacterial strain of the genus Aeribacillus was isolated from Thar Dessert Pakistan. This strain showed significant antibacterial activity against Micrococcus luteus, Staphylococcus aureus, and Pseudomonasaeruginosa. The strain coded as 'SAT4' resembled with Aeribacillus pallidus in the morphological, biochemical and molecular tests. The production of antibacterial metabolites by SAT4 was optimized. These active metabolites were precipitated by 50% ammonium sulphate and purified through sephadex G-75 gel permeation chromatography and reverse phase HPLC. The molecular weight of 37 kDa was examined by SDS-PAGE. The structural elucidation of the purified product was studied by FTIR, 1H and 13C NMR. The X-ray diffractions study showed that the crystals belonged to the primitive orthorhombic lattice (a = 12.137, b = 13.421, c = 14.097 Å) and 3D structure (proposed name: Aeritracin) was determined. This new peptide antibacterial molecule can get a position in pharmaceutical and biotechnological industrial research.

Genome Sequence of Aeribacillus pallidus Strain GS3372, an Endospore-Forming Bacterium Isolated in a Deep Geothermal Reservoir

The genome of strain GS3372 is the first publicly available strain of Aeribacillus pallidus. This endospore-forming thermophilic strain was isolated from a deep geothermal reservoir. The availability of this genome can contribute to the clarification of the taxonomy of the closely related Anoxybacillus, Geobacillus, and Aeribacillus genera.

A novel nucleic lateral flow assay for screening of PHA-producing haloarchaea

Polyhydroxyalkanoates (PHAs) are important for biodegradable plastic production, and prokaryotes play a very important role in PHA production. PHA synthase is a key enzyme for the polymerization of PHAs. There are four classes of PHA synthase. The phaC gene is necessary for the production of all classes of PHA synthase, whereas the phaE gene is necessary for the production of class III PHA synthase. This gene is a biomarker for microorganisms that contain class III PHA synthase, such as haloarchaea. Standard techniques for screening of PHA-producing haloarchaea require time for culturing and have poor specificity and sensitivity. Thus, the phaE biosensor was developed to overcome these issues. PCR and DNA lateral flow biosensor techniques were combined for construction of the phaE biosensor. The phaE biosensor has a high specificity for PHA-producing haloarchaea. The lowest amount of genomic DNA of Haloquadratum walsbyi DSM 16854 that the phaE gene could be detected by the biosensor was approximately 250 fg. The phaE biosensor can be applied for screening of PHA-producing haloarchaea from environmental samples. The phaE biosensor is easy to handle and dispose. For screening PHA-producing haloarchaea, the phaE biosensor requires less time and costs less than the standard methods.