In this review, we presented the industrial status of biomanufactured polyhydroxyalkanoates (PHA), including poly (3-hydroxybutyrate) (PHB), poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB)), and poly (3-hydroxybutyrate-3-hydroxycaproate) (PHBH). A lot of modification studies, aimed at solving problems of poor thermal stability, narrow processing window and other drawbacks of PHA, are discussed. The properties of PHA can be optimized by using proper modification method, in order to expand its applications.
3-Hydroxybutyric Acid ; Biotechnology ; Hydroxybutyrates ; Polyesters ; Polyhydroxyalkanoates ; chemistry

The present study aimed to unravel the carbon metabolism pathway of Acinetobacter sp. TAC-1, a heterotrophic nitrification-aerobic denitrification (HN-AD) strain that utilizes poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as a carbon source. Sodium acetate was employed as a control to assess the gene expression of carbon metabolic pathways in the TAC-1 strain. The results of genome sequencing demonstrated that the TAC-1 strain possessed various genes encoding carbon metabolic enzymes, such as gltA, icd, sucAB, acs, and pckA. KEGG pathway database analysis further verified the presence of carbon metabolism pathways, including the glycolytic pathway (EMP), pentose phosphate pathway (PPP), glyoxylate cycle (GAC), and tricarboxylic acid (TCA) cycle in the TAC-1 strain. The differential expression of metabolites derived from distinct carbon sources provided further evidence that the carbon metabolism pathway of TAC-1 utilizing PHBV follows the sequential process of PHBV (via the PPP pathway)→gluconate (via the EMP pathway)→acetyl-CoA (entering the TCA cycle)→CO₂+H₂O (generating electron donors and releasing energy). This study is expected to furnish a theoretical foundation for the advancement and implementation of novel denitrification processes based on HN-AD and solid carbon sources.
3-Hydroxybutyric Acid ; Carbon/metabolism* ; Polyesters ; Hydroxybutyrates ; Metabolic Networks and Pathways

Poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] belongs to the polyhydroxyalkanoates (PHA) family and possesses promising properties including biocompatibility and biodegradability. In this study, we directly synthesized P(3HB-co-LA) with glucose by introducing the β-ketothiolase and acetoacetyl-CoA reductase from Ralstonia eutropha, the engineered propionate CoA transferase from Clostridium propionicum and the engineered polyhydroxyalkanoate synthase from Pseudomonas fluorescens strain 2P24 into Escherichia coli. The polymer content was 83.9% (W/W), and the molar percentage of lactate reached 1.6%. On this basis, in order to accumulate lactate, we reduced the activity of respiratory chain by deleting the ubiX gene, which is involved in the synthesis of coenzyme Q8. Moreover, we removed the dld gene to avoid the conversion of lactate to pyruvate during the fermentation. With these manipulations, the molar percentage of lactate in the polymer was improved to 14.1%, with an 81.7% (W/W) of polymer content. The test results indicated that the strategy of reducing the activity of respiratory chain effectively increased the lactate units in the polymer, and it contributed a new approach to change the content of monomer components in the polymer.
3-Hydroxybutyric Acid ; Electron Transport ; Escherichia coli ; Lactic Acid ; Metabolic Engineering ; Polyesters

In this study, the Autokit Total Ketone Bodies kit (Wako Pure Chemical, Japan), a total ketone measurement assay using an enzymatic method, was evaluated using a Roche Cobas e702 instrument (Roche Diagnostics, Germany). Precision, linearity, carryover, and reference range verification were evaluated with reference to Clinical Laboratory Standards Institute guidelines. Standard materials provided by the manufacturer and patient samples were used for the evaluation. The precision and carryover of the evaluation result satisfied the acceptance criteria. Linearity was also acceptable at more than 0.99. The quantitative Autokit Total Ketone Bodies kit is precise, and can be widely used in clinical laboratories.
3-Hydroxybutyric Acid ; Evaluation Studies as Topic ; Humans ; Ketone Bodies* ; Methods ; Reference Values

Escherichia coli was metabolically engineered to produce poly(glycolate-co-lactate-co-3-hydroxybutyrate) using glucose and xylose as carbon sources. The combinatorial biosynthetic route was constructed by the overexpression of a series of enzymes including D-tagatose 3-epimerase, L-fuculokinase, L-fuculose-phosphate aldolase, aldehyde dehydrogenase, propionyl-CoA transferase, β-ketothiolase, acetoacetyl-CoA reductase, and polyhydroxyalkanoate synthase. Overexpression of polyhydroxyalkanoate granule associated protein significantly improved biopolymer synthesis, and the recombinant strain reached 3.73 g/L cell dry weight with 38.72% (W/W) biopolymer content. A co-culture engineering strategy was developed to produce biopolymer from a mixture of glucose and xylose, achieving 4.01 g/L cell dry weight containing 21.54% (W/W) biopolymer. The results of this work offer an approach for simultaneously utilizing glucose and xylose and indicate the potential for future biopolymer production from lignocellulosic biomass.
3-Hydroxybutyric Acid ; Escherichia coli ; Glucose ; Glycolates ; Lactates ; Metabolic Engineering ; Polyesters ; Xylose

PURPOSE: The ketogenic diet (KD) remains a therapy in search of explanation although it is an established treatment for patients with intractable seizures. It was designed to mimic the biochemical changes seen upon fasting, specifically the formation of ketone bodies: acetoacetate (ACA), beta-hydroxybutyrate (BHB), and to a lesser extent, acetone. The present study was designed to investigate the protective effect of BHB on flurothyl-induced seizures in rats. METHODS: Thirty-four male Sprague-Dawley rats were divided into two equal groups. Experimental rats (n=17) were injected intraperitoneally with BHB (20 mmol/kg), while control animals (n=17) with normal saline. Fifteen minutes later, seizures were chemically induced by flurothyl infusion (40 mL/min). Seizure susceptibility was defined as the latency from the start of flurothyl infusion to the onset of a generalized seizure. Shorter latencies reflected greater seizure susceptibility. RESULTS: The mean (+/- SEM) latency to the onset of a generalized seizure in the experimental animals treated with BHB was 476.5 +/- 13.9 seconds, which was significantly longer (P < 0.05) than the control (438.0 +/- 10.5 seconds). CONCLUSION: This study demonstrated the significant decrease in flurothyl-induced seizure susceptibility in rats treated with BHB. Our results suggest that BHB may be directly anticonvulsant.
3-Hydroxybutyric Acid ; Acetoacetates ; Acetone ; Animals ; Fasting ; Flurothyl ; Humans ; Hydrazines ; Ketogenic Diet ; Male ; Rats ; Rats, Sprague-Dawley ; Seizures

Polyhydroxyalkanoates (PHAs), as a novel class of biopolymer, are attracting more attention due to their diverse material properties and environment-independent biodegradability. Here we report the preparation of PHA exhibiting efficient antibacterial activity by embedding Nisin, a food additive generally recognized as safe, into poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), a type of PHA with high biocompatibility. We first prepared Nisin-containing PHBHHx films using solvent casting method. Confocal laser scanning microscopy analysis showed that a well-mixed integrated structure of the films with an even distribution of the Nisin particles in the PHBHHx matrices. Then the antimicrobial activity of PHBHHx/Nisin films against Micrococcus luteus was quantified on agar plate by measuring the size of inhibition zone. Cultivation in liquid media further confirmed the releasing of Nisin from the films and the long-time antibacterial activity. Results showed that the threshold of Nisin concentration for long-time and effective inhibition against bacteria growth is 25 μg/g. These results altogether establish a technological foundation for the application of PHA in biomedicine and food industry.
3-Hydroxybutyric Acid ; chemistry ; Anti-Bacterial Agents ; chemistry ; Caproates ; chemistry ; Micrococcus luteus ; drug effects ; Nisin ; chemistry ; Polyhydroxyalkanoates ; chemistry

PURPOSE: Despite decades of clinical experience with the ketogenic diet (KD), its efficacy and mechanisms of action have been examined in few animal studies. The present study was designed to investigate the effect of a KD on flurothyl-induced seizure susceptibility in rats. METHODS: Twenty male Sprague-Dawley rats were divided into two equal groups. Dietary treatment was initiated at P39. The experimental group was fasted for a day and then fed a KD consisting of [fat] : [protein + carbohydrate] ratio of 4.3 : 1, while the control group was fed a standard rodent chow. On treatment day 21, blood beta-hydroxybutyrate (BHB) levels were assayed and seizures were chemically induced by flurothyl (40 micro l/min). Seizure susceptibility was defined as the latency from the start of flurothyl infusion to the onset of a generalized seizure (loss of posture with bilateral hindlimb tonic extension). Shorter latencies reflect greater seizure susceptibility. RESULTS: Blood BHB levels in the KD-treated group were significantly higher than those of the control group (4.75+/-0.38 [n=10] vs. 0.19+/-0.02 [n=10] mM, respectively ; p<0.01). The latencies to the onset of a generalized seizure were 673.2+/-32.95 [n=10] and 523.0+/-31.11 [n=10] seconds for the KD-treated and control groups, respectively (p<0.01). CONCLUSION: This study demonstrates the significant decrease in the susceptibility of flurothyl-induced seizure in the KD-treated rats. Furthermore, we have established a working animal model from which future mechanistic studies can be based.
3-Hydroxybutyric Acid ; Animals ; Flurothyl ; Hindlimb ; Humans ; Ketogenic Diet* ; Male ; Models, Animal ; Posture ; Rats ; Rats, Sprague-Dawley ; Rodentia ; Seizures*

OBJECTIVETo observe the proliferation and differentiation capacities of mouse induced pluripotent stem cells (miPSCs) cultured in 3-hydroxybutyrate-co-3-hydroxyhexanoate(PHBHHx) three-dimensional films three-dimension films for the purpose of finding a suitable polymeric biomaterials for forming myocardial patches.

METHODSmiPSCs were recovered, passaged, cultured and identified, then miPSCs divided into the experimental and control groups. MiPSCs in the experimental group were cultured with PHBHHx three-dimension films. MiPSCs in the control group were cultured with traditional culture dish. Stem cell culture medium or differential medium were added to miPSCs to detecte cell vitality by CCK-8 after 72 hours or to measure the cTnT expression of miPSCs through immunofluorescence or the cTnT expression quantity through flow cytometry after 15 days.

RESULTSCell activity assay showed that the absorbance values were 0.836 ± 0.038 in the experimental group, 0.312 ± 0.004 in the control group (P<0.05). Scanning electron microscope (SEM) observation showed that miPSCs grew well on the PHBHHx dimensional films with normal shape. Immunofluorescence results demonstrated positive cTnT expression in both groups and flow cytometry measured cTnT expression was (60.32 ± 1.76)% in the experimental group and (47.54 ± 1.46)% in the control group (P<0.05).

CONCLUSIONSmiPSCs can survive, proliferate and differentiate on PHBHHx dimensional films. miPSCs proliferation and differentiation capacities are significantly higher in PHBHHx three-dimensional films culture compared with the traditional cell culture.

OBJECTIVE: To investigate the inhibitory effect of ketogenic diet (KD) on growth of neuroblastoma in mice. METHODS: BALB/c-nu mouse models bearing neuroblastoma xenografts were established by subcutaneous injection of human neuroblastoma cell line (SH-SY5Y). When the tumor volume reached 250 mm3, the mice were randomized into SD group with standard diet and PBS treatment, KD group with ketogenic diet and PBS treatment, and CP+KD group with ketogenic diet and cyclophosphamide (60 mg·kg·day) treatment, =8. The tumor volume, body weight, blood glucose, ketone body (β-Hydroxybutyrate) levels, and hepatic steatosis in the mice were assessed. The expressions of caspase-3 and caspase-8 were detected by Western blotting, and Ki67 expresison was detected using immunohistochemistry (IHC). Transmission electron microscopy (TEM) was employed for the autophagosomes, and the autophagic protein Beclin1, LC3A/B and P62 were detected by IHC and Western blotting. RESULTS: On day 28 post tumor cell injection, the mice in KD and CP+KD groups could prolong the overall survival rates than that in SD group ( < 0.001). On day 22 post the injection, the tumor volume in KD group was smaller than that in SD group ( < 0.05); on 16, 19, and 22 day post the injection, the tumor volume in CP+KD group was smaller than that in SD group ( < 0.01). The mice in SD group showed greater body weight on day 19 and higher blood glucose level on day 13 post the injection than those in the other two groups ( < 0.05). Blood ketone level and hepatic steatosis score were higher and glucose ketone index (GKI) was lower in KD and CP+KD groups than those in SD group (all < 0.05). The expressions of Ki67 and apoptotic proteins were detected in the tumor tissues of all groups. TEM revealed more autophagosomes in the tumor tissues of KD group than that of SD group. P62 expression was lowered ( < 0.01) and Beclin1 and LC3A/B expressions were up-regulated in the tumor tissues of KD group ( < 0.05), which is consisitent with IHC. CONCLUSIONS KD has a strong anti-tumor effect in the xenograft mouse model possibly by regulating cell autophagy.
3-Hydroxybutyric Acid ; Animals ; Blood Glucose ; Cell Line, Tumor ; Diet, Ketogenic ; Humans ; Mice ; Mice, Inbred BALB C ; Neuroblastoma