Interactions between lemongrass and lavender essential oils in combination with ampicillin influencing antibacterial activity on Sporosarcina ureae and Serratia liquefaciens

The purpose of this study is to determine the effects of various combinations of essential oils (EOs) with antibiotics on bacterial growth. The molecular mechanisms behind the effects of individual phytochemicals in EOs and antibiotics is well understood, unlike the mechanisms behind the interactions between multiple phytochemicals and antibiotics in a mixture. Serratia liquefaciens and Sporosarcina ureae were exposed to various treatments of different combinations of Lavandula officinalis (lavender oil), Cymbopogon citratus (lemongrass oil) with ampicillin. For each treatment group, mean zones of inhibition (ZOI) were measured after exposure for 48 hours. Controls for both species did not yield any ZOI whereas all other treatments resulted in the inhibition of bacterial growth in both Serratia liquefaciens and Sporosarcina ureae. Statistical analyses showed that the combination of lemongrass oil and ampicillin was significantly more effective than all other treatments for Serratia liquefaciens. The lemongrass oil and ampicillin treatment was the only treatment that displayed additive effects. All treatments for Sporosarcina ureae, with the exception of the control and lavender oil treatments, showed a significantly higher mean ZOI when compared to control and lavender oil treatments. It was concluded that lemongrass oil was a better candidate to be included in antibacterial cocktails than lavender oil. However, further investigation is required to elucidate EOs that interact synergistically with ampicillin when acting on Serratia liquefaciens and Sporosarcina ureae. Additionally, further investigation into the molecular mechanisms behind the interactions of the components found in these EOs with ampicillin is required.

Improving the strength of sandy soils via ureolytic CaCO₃ solidification by <i>Sporosarcina ureae</i>

“Microbially induced carbonate precipitation” (MICP) is a biogeochemical process that can be applied to strengthen materials. The hydrolysis of urea by microbial catalysis to form carbonate is a commonly studied example of MICP. In this study, Sporosarcina ureae, a ureolytic organism, was compared to other ureolytic and non-ureolytic organisms of Bacillus and Sporosarcina genera in the assessment of its ability to produce carbonates by ureolytic MICP for ground reinforcement. It was found that S. ureae grew optimally in alkaline (pH ∼ 9.0) conditions which favoured MICP and could degrade urea (units U mL−1 represent µmol min−1 mL OD600) at levels (30.28 U mL−1) similar to S. pasteurii (32.76 U mL−1), the model ureolytic MICP organism. When cells of S. ureae were concentrated (OD600 ∼ 15–20) and mixed with cementation medium containing 0.5 M calcium chloride (CaCl2) and urea into a model sand, repeated treatments (3 × 24 h) were able to improve the confined direct shear strength of samples from 15.77 kPa to as much as 135.80 kPa. This was more than any other organism observed in the study. Imaging of the reinforced samples with scanning electron microscopy and energy-dispersive spectroscopy confirmed the successful precipitation of calcium carbonate (CaCO3) across sand particles by S. ureae. Treated samples were also tested experimentally according to model North American climatic conditions to understand the environmental durability of MICP. No statistically significant (p < 0.05, n= 3) difference in strength was observed for samples that underwent freeze–thaw cycling or flood-like simulations. However, shear strength of samples following acid rain simulations fell to 29.2 % of control MICP samples. Overall, the species S. ureae was found to be an excellent organism for MICP by ureolysis to achieve ground strengthening. However, the feasibility of MICP as a durable reinforcement technique is limited by specific climate conditions (i.e. acid rain).

Improving the Strength of Sandy Soils via Ureolytic CaCO₃ Solidification by <i>Sporosarcina ureae</i>

Microbial induced carbonate precipitation (MICP) is a biogeochemical process that can be applied to strengthen materials. The hydrolysis of urea by microbial catalysis to form carbonate is a commonly studied example of MICP. In this study, Sporosarcina ureae, a ureolytic organism, was compared to other ureolytic and non-ureolytic organisms of Bacillus and Sporosarcina in the assessment of its ability to produce carbonates by ureolytic MICP for ground reinforcement. It was found that S. ureae grew optimally in alkaline (pH ~ 9.0) conditions which favoured MICP and could degrade urea (30.28 U/mL) at levels similar to S. pasteurii (32.76 U/mL), the model ureolytic MICP organism. When cells of S. ureae were concentrated (OD600 ~ 15–20) and mixed with cementation medium containing 0.5 M calcium chloride (CaCl2) and urea into a model sand, repeated treatments (3 × 24 h) were able to improve the confined direct shear strength of samples from 15.77 kPa to as much as 135.8 kPa. This was more than any other organism observed in the study. Imaging of the reinforced samples with scanning electron microscopy and energy dispersive spectroscopy confirmed the successful precipitation of calcium carbonate (CaCO3), organized as calcite, across sand particles by S. ureae. Treated samples were also tested experimentally according to model North American climatic conditions to understand the environmental durability of MICP. No significant (p

Production, Secretion, and Cell Surface Display of Recombinant Sporosarcina ureae S-Layer Fusion Proteins in Bacillus megaterium

ABSTRACTMonomolecular crystalline bacterial cell surface layers (S-layers) have broad application potential in nanobiotechnology due to their ability to generate functional supramolecular structures. Here, we report thatBacillus megateriumis an excellent host organism for the heterologous expression and efficient secretion of hemagglutinin (HA) epitope-tagged versions of the S-layer protein SslA fromSporosarcina ureaeATCC 13881. Three chimeric proteins were constructed, comprising the precursor, C-terminally truncated, and N- and C-terminally truncated forms of the S-layer SslA protein tagged with the human influenza hemagglutinin epitope. For secretion of fusion proteins, the open reading frames were cloned into theEscherichia coli-Bacillus megateriumshuttle vector pHIS1525. After transformation of the respective plasmids intoBacillus megateriumprotoplasts, the recombinant genes were successfully expressed and the proteins were secreted into the growth medium. The isolated S-layer proteins are able to assemblein vitrointo highly ordered, crystalline, sheetlike structures with the fused HA tag accessible to antibody. We further show by fluorescent labeling that the secreted S-layer fusion proteins are also clustered on the cell envelope ofBacillus megaterium, indicating that the cell surface can servein vivoas a nucleation point for crystallization. Thus, this system can be used as a display system that allows the dense and periodic presentation of S-layer proteins or the fused tags.

Postdivisional Synthesis of the Sporosarcina ureae DNA Translocase SpoIIIE either in the Mother Cell or in the Prespore Enables Bacillus subtilis To Translocate DNA from the Mother Cell to the Prespore

ABSTRACT The differentiation of vegetative cells of Bacillus subtilis into spores involves asymmetric cell division, which precedes complete chromosome partitioning. The DNA translocase SpoIIIE is required to translocate the origin distal 70% of the chromosome from the larger mother cell into the smaller prespore, the two cells that result from the division. We have tested the effect of altering the time and location of SpoIIIE synthesis on spore formation. We have expressed the spoIIIE homologue from Sporosarcina ureae in B. subtilis under the control of different promoters. Expression from either a weak mother cell-specific (σE) promoter or a weak prespore-specific (σF) promoter partly complemented the sporulation defect of a spoIIIE36 mutant; however, expression from a strong prespore-specific (σF) promoter did not. DNA translocation from the mother cell to the prespore was assayed using spoIIQ-lacZ inserted at thrC; transcription of spoIIQ occurs only in the prespore. Translocation of thrC::spoIIQ-lacZ into the prespore occurred efficiently when spoIIIE Su was expressed from the weak σE- or σF-controlled promoters but not when it was expressed from the strong σF-controlled promoter. It is speculated that the mechanism directing SpoIIIE insertion into the septum in the correct orientation may accommodate slow postseptational, prespore-specific SpoIIIE synthesis but may be swamped by strong prespore-specific synthesis.