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Poly-β-hydroxybutyrate (PHB) is a biodegradable polymer, synthesized as carbon and energy reserve by bacteria and archaea. To the best of our knowledge, this is the first report on PHB production by a rare actinomycete species, Rhodococcus pyridinivorans BSRT1-1. Response surface methodology (RSM) employing central composite design, was applied to enhance PHB production in a flask scale. A maximum yield of 3.6 ± 0.5 g/L in biomass and 43.1 ± 0.5 wt% of dry cell weight (DCW) of PHB were obtained when using RSM optimized medium, which was improved the production of biomass and PHB content by 2.5 and 2.3-fold, respectively. The optimized medium was applied to upscale PHB production in a 10 L stirred-tank bioreactor, maximum biomass of 5.2 ± 0.5 g/L, and PHB content of 46.8 ± 2 wt% DCW were achieved. Furthermore, the FTIR and 1 H NMR results confirmed the polymer as PHB. DSC and TGA analysis results revealed the melting, glass transition, and thermal decomposition temperature of 171.8, 4.03, and 288 °C, respectively. In conclusion, RSM can be a promising technique to improve PHB production by a newly isolated strain of R. pyridinivorans BSRT1-1 and the properties of produced PHB possessed similar properties compared to commercial PHB.

In this study, the performance of a near-infrared (NIR) fiber-optic probe coupled with stability competitive adaptive reweighted sampling (SCARS) was investigated for the analysis of acetic acid, ethanol, total soluble solids, caffeic acid, gallic acid, and tannic acid in the broth of pineapple vinegar during fermentation. The NIR spectra of the broth samples in the region of 11,536–3956 cm−1 were collected during vinegar fermentation promoted by Acetobacter aceti. This continuous biological process led to changes in the concentrations of all analytes studied. SCARS provided optimized and stabilized NIR spectral variables for the construction of a partial least squares (PLS) model for each analyte using a small number of optimal variables (under 88 variables). The SCARS-PLS model outperformed the conventional PLS model, and achieved excellent accuracy in accordance with ISO 12099:2017 for the four prediction models of acetic acid, ethanol, caffeic acid, and gallic acid, with root-mean-square error of prediction values of 0.137%, 0.178%, 0.637 μg/mL and 0.640 μg/mL, respectively. In contrast, only an acetic acid content prediction model constructed via the conventional PLS method and using the whole spectral region (949 variables) could pass with acceptable accuracy. These results indicate that the NIR optical probe coupled with SCARS is an appropriate method for the continuous monitoring of multianalytes during vinegar fermentation, particularly acetic acid and ethanol contents, which are indicators of the finished fermentation of pineapple vinegar.

Ganoderma sichuanense, a unique antler-type variant of the Ganoderma genus, is renowned for its bioactive compounds, including polysaccharides, triterpenoids, and phenolic compounds, which offer several health benefits. This study aimed to optimize the growth of G. sichuanense and the production of bioactive compounds using different types and concentrations of fruit peels as substrates in both solid and liquid media. The results indicate that durian peel was the most effective for mycelial growth on solid medium, with a maximum observed mycelium growth rate of 9.4 mm/day. In the liquid medium, when using mango, durian, and mangosteen peels as substrates, there was no significant difference in the maximum dry mycelium yield among the three types of fruit peels, ranging from 10.98 to 11.12 g/ L ( p  ≥ 0.05). In a 21-day liquid culture using various fruit peels, 0.1% (w/v) durian peel exhibited the most significant impact on the production of polysaccharides and phenolic compounds in the dried mycelium, with contents of 74.25 mg/g and 57.26 mg GAE/g, respectively. Employing 0.1% (w/v) durian peel for 21 days resulted in the achievement of 21.52 mg/g of triterpenoids as a secondary metabolite. Therefore, the use of fruit peel as a supplement to grow mushrooms can add value to the production of bioactive compounds by an antler-type variant of the G . sichuanense . This work highlights the benefits of enhancing biotechnological production, promoting sustainable waste management, and utilizing fruit peels, a byproduct of the food industry, for bioactive compound production. Graphical abstract

This research investigated the impact of the concentration of pineapple juice on the characteristics of pineapple wine during fermentation with Saccharomyces cerevisiae var. burgundy. Three ratios of fresh pineapple juice to water were mixed to obtain three treatments, which were T1—2:1, T2—1:1, and T3—1:2. The °Brix and pH of all pineapple juice and water ratios were adjusted to 25 and 4, respectively. The results showed that changes in alcohol, pH, Total Soluble Solids (TSS), Total Titratable Acidity (TAA, as citric acid), and Volatile Acidity (VA, as acetic acid) during the 10-day fermentation among three treatments were significantly different. The highest alcohol content was obtained from the 2:1 with values of 10.71% (v/v). The mixed ratio at 1:1 and 1:2 obtained the alcohol value of 9.61 and 8.35% (v/v), respectively. After ten days of fermentation, TSS, pH values, TAA, and VA were in the range of 9.7–13 °Brix, 3.56–3.82, 0.384–0.448, and 0.0013–0.0016, respectively. However, the appearance, aroma, and taste of all ratios were not significantly different. Sweetness and overall liking, wine with pineapple juice/water ratio at 2:1 had the highest score (p ≤ 0.05). The total antioxidant activities determined by DPPH and total phenolic content were 0.91 mmol/L TE and 365.80 mg/L GAE, respectively, as confirmed by FTIR spectral analyses.

Pineapples are a tropical fruit with high nutritional value and high vitamin and sugar contents. In this study, low-grade pineapples were fermented to produce vinegar using surface culture fermentation (SCF), which involved the addition of dragon fruit juice, to compare the quality and antioxidant activity of different preparations of vinegar. The highest acetic acid concentration (7.35%) was obtained from pineapple vinegar after 20 days of incubation. Vinegar made from mixed pineapple and dragon fruit juice without peel and vinegar with pineapple and dragon fruit juice with peel had acetic acid concentrations of up to 6.20% and 4.50%, respectively. The mixed-fruit vinegar of pineapple and dragon fruit juice with peel displayed the highest antioxidant activity at 210.74 µg/g TE, while no significant difference was found between the other two vinegars (189.52 vs. 187.91 µg/L TE). Notably, the volatile compounds detected in the vinegars were alcohols and esters, which may contribute to the distinct aroma. Overall, the addition of dragon fruit juice with peel to pineapple vinegar increased the phenolic content and antioxidant activity; however, fermentation was slightly slower than that of the other two test materials.

Oil palm empty fruit bunches (EFBs) are an attractive lignocellulosic material that can be used as a cheap renewable feedstock to produce organic acids and many other value-added products. This research is aimed at investigating the potential of steam-exploded oil palm EFBs for the production of fumaric acid, a food additive widely used for flavor and preservation, through a separate hydrolysis and fermentation process using the selected fungal isolate Rhizopus oryzae K20. To develop an efficient method for the recovery and purification of fumaric acid from fermented oil palm EFBs, a two-stage precipitation protocol was employed, followed by an activated carbon-mediated polishing step to remove contaminants. After these two processes were accomplished, a recovery yield of 81.2% and a purity of 83.5% were achieved.

This study used Fourier transform-near-infrared (FT-NIR) spectroscopy equipped with the liquid probe in combination with an efficient wavelength selection method named searching combination moving window partial least squares (SCMWPLS) for the determination of ethanol, total soluble solids, total acidity, and total volatile acid contents in pineapple fruit wine fermentation using Saccharomyces cerevisiae var. burgundy. Two fermentation batches were produced, and the NIR spectral data of the calibration samples in the wavenumber range of 11,536–3952 cm−1 were obtained over ten days of the fermentation period. SCMWPLS coupled with second derivatives searched and optimized spectral intervals containing useful information for building calibration models of four parameters. All models were validated by test samples obtained from an independent fermentation batch. The SCMWPLS models showed better predictions (the lowest value of prediction error and the highest value of residual predictive deviation) with acceptable statistical results (under confidence limits) among the results achieved by using the whole region. The results of this study demonstrated that FT-NIR spectroscopy using a liquid probe coupled with SCMWPLS could select the optimized wavelength regions while reducing spectral points and increasing accuracy for simultaneously monitoring the evolution of four chemical parameters in pineapple fruit wine fermentation.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] is a bacterial copolymer in the polyhydroxyalkanoates (PHAs) family, a next-generation bioplastic. Our research team recently engineered a newly P(3HB-co-3HHx)-producing bacterial strain, Cupriavidus necator PHB 4/pBBR_CnPro-phaC . This strain can produce P(3HB-co-2 mol% 3HHx) using crude palm kernel oil (CPKO) as a sole carbon substrate. However, the improvement of P(3HB-co-3HHx) copolymer production by this strain has not been studied so far. Thus, this study aims to enhance the production of P(3HB-co-3HHx) copolymers containing higher 3HHx monomer compositions using response surface methodology (RSM). Three significant factors for P(3HB-co-3HHx) copolymers production, i.e., CPKO concentration, sodium hexanoate concentration, and cultivation time, were studied in the flask scale. As a result, a maximum of 3.6 ± 0.4 g/L of P(3HB-co-3HHx) with 4 mol% 3HHx compositions was obtained using the RSM optimized condition. Likewise, the higher 3HHx monomer composition (5 mol%) was obtained when scaling up the fermentation in a 10L-stirrer bioreactor. Furthermore, the produced polymer's properties were similar to marketable P(3HB-co-3HHx), making this polymer suitable for a wide range of applications.

In this study, we report the inhibition of Kluyveromyces marxianus TISTR5925 growth and ethanol fermentation in the presence of furan derivatives and weak acids (acetic acid and lactic acid) at high temperatures. Cassava pulp, obtained as the waste from starch processing, was collected from 14 starch factories located in several provinces of Thailand. At a high temperature (42 °C), the cassava pulp hydrolysate from some starch factories strongly inhibited growth and ethanol production of both K. marxianus (strain TISTR5925) and Saccharomyces cerevisiae (strain K3). HPLC detected high levels of lactic acid and acetic acid in the hydrolysates, suggesting that these weak acids impaired the growth of K. marxianus at high temperature. We isolated Trp-requiring mutants that had reduced tolerance to acetic acid compared to the wild-type. This sensitivity to acetic acid was suppressed by supplementation of the medium with tryptophan.

This study focused on decolorization of 2 reactive dyes; Reactive Blue 19 (RBBR) and Reactive Black 5 (RB5), by selected white-rot fungus Datronia sp. KAPI0039. The effects of reactive dye concentration, fungal inoculum size as well as pH were studied. Samples were periodically collected for the measurement of color unit, Laccase (Lac), Manganese Peroxidase (MnP), and Lignin Peroxidase (LiP) activity. Eighty-six percent of 1,000 mg L−1 RBBR decolorization was achieved by 2% (w/v) Datronia sp. KAPI0039 at pH 5. The highest Lac activity (759.81 UL−1) was detected in the optimal condition. For RB5, Datronia sp. KAPI0039 efficiently performed (88.01% decolorization) at 2% (w/v) fungal inoculum size for the reduction of 600 mg L−1 RB5 under pH 5. The highest Lac activity (178.57 UL−1) was detected, whereas the activity of MnP and LiP was absent during this hour. The result, therefore, indicated that Datronia sp. KAPI0039 was obviously able to breakdown both reactive dyes, and Lac was considered as a major lignin-degradation enzyme in this reaction.