1. Electrophysiological and Behavioral Responses of an Ambrosia Beetle to Volatiles of its Nutritional Fungal Symbiont
Christopher M Ranger, et al. J Chem Ecol. 2021 May;47(4-5):463-475. doi: 10.1007/s10886-021-01263-0. Epub 2021 Mar 24.
Ambrosia beetles (Coleoptera: Scolytinae) cultivate their fungal symbiont within host substrates as the sole source of nutrition on which the larvae and adults must feed. To investigate a possible role for semiochemicals in this interaction, we characterized electrophysiological and behavioral responses of Xylosandrus germanus to volatiles associated with its fungal symbiont Ambrosiella grosmanniae. During still-air walking bioassays, X. germanus exhibited an arrestment response to volatiles of A. grosmanniae, but not antagonistic fungi Beauveria bassiana, Metarhizium brunneum, Trichoderma harzianum, the plant pathogen Fusarium proliferatum, or malt extract agar. Solid phase microextraction-gas chromatography-mass spectrometry identified 2-ethyl-1-hexanol, 2-phenylethanol, methyl benzoate and 3-methyl-1-butanol in emissions from A. grosmanniae; the latter two compounds were also detected in emissions from B. bassiana. Concentration-responses using electroantennography documented weak depolarizations to A. grosmanniae fungal volatiles, unlike the comparatively strong response to ethanol. When tested singly in walking bioassays, volatiles identified from A. grosmanniae elicited relatively weak arrestment responses, unlike the responses to ethanol. Xylosandrus germanus also exhibited weak or no long-range attraction to the fungal volatiles when tested singly during field trials in 2016-2018. None of the fungal volatiles enhanced attraction of X. germanus to ethanol when tested singly; in contrast, 2-phenylethanol and 3-methyl-1-butanol consistently reduced attraction to ethanol. Volatiles emitted by A. grosmanniae may represent short-range olfactory cues that could aid in distinguishing their nutritional fungal symbiont from other fungi, but these compounds are not likely to be useful as long-range attractants for improving detection or mass trapping tactics.
2. Engineered microbial biofuel production and recovery under supercritical carbon dioxide
Jason T Boock, et al. Nat Commun. 2019 Feb 4;10(1):587. doi: 10.1038/s41467-019-08486-6.
Culture contamination, end-product toxicity, and energy efficient product recovery are long-standing bioprocess challenges. To solve these problems, we propose a high-pressure fermentation strategy, coupled with in situ extraction using the abundant and renewable solvent supercritical carbon dioxide (scCO2), which is also known for its broad microbial lethality. Towards this goal, we report the domestication and engineering of a scCO2-tolerant strain of Bacillus megaterium, previously isolated from formation waters from the McElmo Dome CO2 field, to produce branched alcohols that have potential use as biofuels. After establishing induced-expression under scCO2, isobutanol production from 2-ketoisovalerate is observed with greater than 40% yield with co-produced isopentanol. Finally, we present a process model to compare the energy required for our process to other in situ extraction methods, such as gas stripping, finding scCO2 extraction to be potentially competitive, if not superior.
3. Spectroscopic studies on the in vitro antioxidant capacity of isopentyl ferulate
Keylla C Machado, et al. Chem Biol Interact. 2015 Jan 5;225:47-53. doi: 10.1016/j.cbi.2014.11.008. Epub 2014 Nov 21.
Essential oils have played a prominent role in research on natural products, due to the high level of bioactive constituents, which include those derived from phenylpropanoids or terpenoids. This study aimed to evaluate the antioxidant capacity of isopentyl ferulate (IF) employing in vitro experimental models for elimination of the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS+), hydroxyl (OH) and nitric oxide (NO), as well as its capacity to electron transfer by reducing potential and inhibition of lipid peroxidation by TBARS (thiobarbituric acid reactive substances) method. In all in vitro antioxidants protocols, isopentyl ferulate showed to be potent in a concentration of 54.4 nM, presenting a percentage inhibition of 91.29±0.57, 92.63±0.28, 83.62±0.18, 77.07±0.72 and 79.51±0.32% for DPPH, ABTS+, hydroxyl, nitric oxide and TBARS level, respectively. The increase of absorbance at 700 nm in the concentrations of 3.4, 6.8, 13.6, 27.2 and 54.4 nM shows the reducing potential of IF. Similar results were obtained with Trolox (559 nM), a hydrophilic synthetic analogue of α-tocopherol, which is widely used as a standard antioxidant. The present study demonstrated that isopentyl ferulate has an antioxidant activity in vitro experimental models, suggesting that this compound could enhance the development of a new product with antioxidant properties. However, further in vivo studies are needed to assign possible implications in the treatment of diseases related with free radicals.
