Hexanoic acid

Cyphos IL 101 (Merck Life Science Co., Ltd, Shanghai, China), Aliquat 336 (Alfa Aesar Chemical Co., Ltd, Beijing, China), CTA (cellulose triacetate) (Acros Organics, New Jersey, USA), and DCM (dichloromethane) (Sinopharm Chemical Reagent Co., Ltd, Shanghai, China) were used to cast the PIMs. Hexanoic acid was purchased from Merck Life Science Co., Ltd. (Shanghai, China). Acetic acid, HCl, H₂SO₄, NaOH, and Na₂CO₃ used in the experiments were of an analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). All chemicals were used without further purification. Deionized water was used to prepare all aqueous solutions. The commercial cation exchange membrane (CJMC-5) was obtained from Hefei Chemjoy Polymer Material Co. Ltd. (Hefei, China).

The pure samples of the following compounds: nonanal, 2,3-butanedione (diacetyl), acetic acid, 3-methylbutanal, butanoic acid, 2-methylpropanoic acid, 3-methylbutanoic acid, pentanoic acid, octanoic acid, and hexanoic acid were purchased from Merck (Darmstadt, Germany). (E)-2-nonenal, 2-nonanone, phenyl acetaldehyde, δ-decalactone, 2-methoxy-4-vinylphenol, 4,5-epoxy-(E)-2-decanal, (E,E)-2,4-decadienal, (Z)-2-nonenal, methional, and 4-hydroxy-2,5-dimethyl-3 (2H)-furanone were from Sigma–Aldrich (Taufkirchen, Germany). 1-Octen-3-one was from Symrise (Holzminden, Germany). The following labelled compounds were synthesized according to the literature cited; [²H₂]-butanoic acid [19 (link)]; 3-[²H₂]-methylbutanal [11 (link)]; [²H_2-5]-2-acetyl-1-pyrroline [20 (link)]; [¹³C₄]-2,3-butanedione [21 (link)]; [²H]-(E,E)-2,4-decadienal [22 ]; [¹³C₂]-acetic acid [22 ]; [²H₂]-3-methylbutanoic acid [23 (link)]; [²H₃]-2-methoxyphenol [24 (link)]; [²H₅]-phenyl acetaldehyde [25 (link)]; [¹³C₂]-4-hydroxy-2,5-dimethyl-3(2H)-furanone [26 (link)]; [²H₂]-δ-decalactone [27 (link)]; [²H₂]-methional [27 (link)]. Lastly, [²H₃]-hexanoic acid was from Cambridge Isotope Laboratories (Euriso-top GmbH, Saarbrucken, Germany).

The antibiotics (AB) used in this study were amoxicillin, ampicillin, doxycycline, lincomycin, neomycin, penicillin G, and colistin (all obtained from Alpha Aesar, Thermo Fisher GmbH, Kandel, Germany); AB stock solutions were prepared in BHI. Organic acids (OA) and nature-identical compounds (NIC) utilized in this study were citric acid, sorbic acid, benzoic acid, butyric acid, hexanoic acid, formic acid, fumaric acid, lactic acid, malic acid, and propionic acid (stocks prepared in BHI); and octanoic acid, decanoic acid, dodecanoic acid, thymol, carvacrol, eugenol, vanillin, α-pinene, eucalyptol, limonene, linalool, and menthol (stocks prepared in BHI supplemented with ethanol at a final concentration ≤ 3.5% to increase solubility); all OA and NIC were obtained from Merck KGaA, Darmstadt, Germany. Each solution was buffered to ensure a final pH of 6.5, filter-sterilized and diluted in sterile BHI to reach the final concentration tested.

All
chemicals were used
directly as provided commercially without additional purification.
Milli Q water was obtained using an IQ 7000 purifying system. P25
TiO₂, HAuCl₄·3H₂O, PdCl₂, acetone (99.9%, CH₃COCH₃), sodium
hydroxide (reagent grade, 97%, powder, NaOH), 1-phenylethanol (97%),
hexanoic acid (99%), pentane (99%), lauric acid (97%), palmitic acid
(99%), stearic acid (98%), oleic acid (97%), undecane (99%), pentadecane
(99%), heptadecane (99%), p-xylene (99.5%, as internal
GC standard), different solvents including dodecane (99%), PhMe (99%),
THF (99%), DMF (99%) and dichloroethane (99%) were purchased from
Sigma-Aldrich. Jatropha oil was purchased from the Shenyu company
in Yunnan Province, China. Wasted cooking oil and wasted hot-pot oil
were collected from Sichuan Province, China.

NAD, NADH, AICAR, hexanoic acid, octanoic acid, octanal, betaine aldehyde, betaine, and 2-aminoadipic acid were obtained (Sigma). Cholesterol, sphingomyelin, DOPC, DOPE, DOPS, and phosphatidic acid (PA) were obtained (Avanti). Alexa 546-conjugated transferrin (Tf), Alexa 555-conjugated forms of EGF, dextran, and CT were also obtained (Invitrogen). Fugene 6 Transfection Reagent was from Promega. RNAiMax was from Invitrogen. Preparations of coatomer, ARF1, ARFGAP1, BARS, Golgi membrane, and cytosol have been described^{14 (link),16 (link)}. To generate recombinant ALDH7A1, the human cDNA was expressed in bacteria (BL21) using the pET-15b vector (Novagen), followed by isolation of the 6×-his tagged form of ALDH7A1 using a nickel column. AMPK was purified from cells by transfection of a flag-tagged construct into HeLa cells, followed by immunoprecipitation of the tagged construct from cell lysates using an anti-flag antibody (M2).

Hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, polylactic acid (PLA), polycaprolactone (PCL) and polyethylene succinate (PES) was purchased from Sigma Chemical Co. (St. Louis, MO). All other analytical grade products, chemicals and dyes were from either Sigma Chemical Co. (St. Louis, MO) or Fisher Scientific (Toronto, ON). To prepare the various PHA polymers, the P. putidaLS46 was cultivated in Ramsay’s minimal medium (RMM) (Ramsay et al., 1994 (link)) at 30°C in 7 L Applicon Bioreactor with hexanoic, octanoic, nonanoic, or decanoic acid as the sole carbon source (Blunt et al., 2018 (link)). A copolymer of 3-hydroxybutyrate and 3-hydroxyvalrate [Poly (3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV] was prepared from biodiesel fatty acid supplemented with 0.5% valeric acid using CuprividusnecatorH16 (Sharma et al., 2016 (link)). The monomer compositions of these PHA polymers were determined (Sharma et al., 2011 (link)) and are shown in Table 1. Luria Bertani (LB) broth and agar were used for the growth of E. coli DH5α and E. coli BL21 (DE3) cells.

2-Ethyl-2-oxazoline (EOZ),
2-phenyl-2-oxazoline (PhOZ), chlorobenzene, methanol, and hexanoic
acid were purchased from Sigma-Aldrich. Monomers and chlorobenzene
were dried over calcium hydride (CaH₂), distilled, and
kept over 4 Å molecular sieves before their use in polymerizations.
Trifluoromethanesulfonic acid (TfOH) and oxalyl chloride were purchased
from Acros Organics. Butyronitrile and 2-chloroethylamine hydrochloride
were purchased from ABCR. Sodium hydroxide (NaOH) and potassium hydroxide
(KOH) were purchased from ISOLAB. Ethanolamine, CaH_2, dichloromethane
(DCM), zinc acetate dihydrate (Zn(OAc)₂·2H₂O), triethylamine (TEA), and sodium sulfate (Na₂SO₄) were purchased from Merck. Unless it is stated otherwise,
all chemicals were used as received.