Fermentable sugar recovery from durian peel by using ultrasound-assisted chemical pretreatment

Durian peel, an abundant waste in Malaysia could be a potential substrate for fermentable sugar recovery for value-added biochemical production. Common pretreatment such as acid or alkaline pretreatment resulted in the need for extensive solid washing which generated wastewater. Herein, this study aims to introduce sonication on top of chemical pretreatment to destruct lignin and reduce the chemical usage during the durian peel pretreatment process. In this study, the morphology and the chemical composition of the pretreated durian peels were studied. The sugar yield produced from the chemical pretreatment and the combined ultrasound and chemical pretreatment were compared. The morphology and chemical structure of durian peels were investigated by Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) analysis and X-ray diffraction (XRD). The SEM images showed that the structural change became more significant when sonication was introduced. Second, XRD profile indicated a relatively higher crystallinity index and FTIR spectra displayed a lower intensity of lignin and hemicellulose for ultrasound plus alkaline (UB) pretreatment as compared to acid, alkaline and ultrasound plus acid (UA) pretreatment. UB and UA pretreatment portrayed higher yield (376.60 ± 12.14 and 237.38 ± 3.96 mg reducing sugar/g dry biomass, respectively) than their controls without the application of ultrasound. Therefore, it could be concluded that ultrasound was able to intensify the fermentable sugar recovery from durian peel by inducing physical and chemical effect of cavitation to alter the morphology of durian peel. Fermentation of UB treated durian peel resulted in 2.68 mol hydrogen/mol consumed sugar and 131.56 mL/Lmedium/h of hydrogen productivity. This study is important because it will shed light on a way to handle durian waste disposal problems and generate fermentable sugars for the production of high value-added products.

Exploring pineapple peel hydrolysate as a sustainable carbon source for xylitol production

This study explores utilizing pineapple peel (PP) hydrolysate as a promising carbon source for xylitol production, covering scopes from the pre-treatment to the fermentation process. The highest xylose concentration achieved was around 20 g/L via mild acid hydrolysis (5% nitric acid, 105 °C, 20-min residence time) with a solid loading of 10%. Two sets fermentability experiments were carried out of varying pH levels in synthetic media that includes acetic acid as the main inhibitors and hydrolysate supplemented with diverse nitrogen source. The results revealed that pH 7 exhibited the highest xylitol production, yielding 0.35 g/g. Furthermore, urea was found to be a highly promising and cost-effective substitute for yeast extract, as it yielded a comparable xylitol production of 0.31 g/g with marginal difference of only 0.01 g/g compared to yeast extract further highlights the viability of urea as the preferred option for reducing xylitol production cost. The absence of a significant difference between the synthetic media and hydrolysate, with only a marginal variance of 0.35 to 0.32 g/g, implies that acetic acid is indeed the primary constraint in xylitol production using PP hydrolysate. The study sheds light on PP biomass's potential for xylitol production, aligning economic benefits with environmental sustainability and waste management.

Biotechnological enhancement of lactic acid conversion from pretreated palm kernel cake hydrolysate by Actinobacillus succinogenes 130Z

The aim of this study was to establish an improved pretreatment and fermentation method i.e. immobilized cells for high recovery of fermentable sugars from palm kernel cake (PKC) and its effects on fermentability performance by Actinobacillus succinogenes 130Z in the conversion of the fermentable sugar to lactic acid. The effects of oxalic acid concentrations (1-6% w/v) and residence times (1-5 h) on the sugar recovery were initially investigated and it was found that the highest mannose concentration was 25.1 g/L at the optimum hydrolysis conditions of 4 h and 3% (w/v) oxalic acid. The subsequent enzymatic saccharification of the pretreated PKC afforded the highest enzymatic digestibility with the recovered sugars amounting to 25.18 g/L and 9.14 g/L of mannose and glucose, respectively. Subsequently, the fermentability performance of PKC hydrolysate was evaluated and compared in terms of cultivation phases (i.e. mono and dual-phases), carbonate loadings (i.e. magnesium and sodium carbonates), and types of sugars (i.e. glucose and mannose). The highest titer of 19.4 g/L lactic acid was obtained from the fermentation involving A. succinogenes 130Z in dual-phase cultivation supplemented with 30 g/L of magnesium carbonate. Lactic acid production was further enhanced by using immobilized cells with coconut shell-activated carbon (CSAC) of different sizes (A, B, C, and D) in the repeated batch cultivation of dual-phase fermentation producing 31.64 g/L of lactic acid. This work sheds light on the possibilities to enhance the utilization of PKC for lactic acid production via immobilized A. succinogenes 130Z.

Biotechnological enhancement of lactic acid conversion from palm kernel cake by immobilized Actinobacillus succinogenes 130Z.. [DOI: 10.21203/rs.3.rs-2469941/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The aim of this study was to establish an improved pretreatment and fermentation method i.e. immobilized cells for high recovery of fermentable sugars from PKC and its effects on fermentability performance by Actinobacillus succinogenes 130Z in the conversion of lactic acid. The effects of oxalic acid concentrations (1–6% w/v) and residence times (1–5 h) on the sugar recovery were initially investigated and it was found that the highest mannose concentration was 25.1 g/L at the optimum hydrolysis conditions of 4 h and 3% (w/v) oxalic acid. The subsequent enzymatic saccharification of the pretreated PKC afforded the highest enzymatic digestibility with the recovered sugars amounting to 25.18 g/L and 9.14 g/L of mannose and glucose, respectively. Subsequently, the fermentability performance of PKC hydrolysate was evaluated and compared in terms of cultivation phases (i.e. mono and dual-phases), carbonate loadings (i.e. magnesium and sodium carbonates), and types of sugars (i.e. glucose and mannose). The highest titer of 19.4 g/L lactic acid was obtained from the fermentation involving A. succinogenes 130Z in dual-phase cultivation supplemented with 30 g/L of magnesium carbonate. Lactic acid production was further enhanced by using immobilized cells with coconut shell-activated carbon (CSAC) of different sizes (A, B, C, and D) in the repeated batch cultivation of dual-phase fermentation producing 31.64 g/L of lactic acid. This work sheds light on the possibilities to enhance the utilization of PKC for lactic acid production via immobilized A. succinogenes 130Z.

Low cost nutrient-rich oil palm trunk bagasse hydrolysate for bio-succinic acid production by Actinobacillus succinogenes

Economical source of succinic acid (SA) is most sought-after as a key platform chemical for a wide range of applications. Low-cost production of bio-succinic acid (bio-SA) from a renewable biomass resource i.e., oil palm trunk (OPT) is reported in this paper. Apart from carbon source, nitrogen source and mineral salts are other important nutrients affecting microbial cell growth and bio-SA biosynthesis by Actinobacillus succinogenes 130Z. In order to access and optimize nutrient requirement of the latter two sources, their effects in terms of types and concentrations were investigated. The findings highlighted the importance of selecting proper nitrogen source in A. succinogenes fermentation. The possibility of producing bio-SA from OPT economically can be achieved through minimal supply of 5 g/L yeast extract compared to that generally supplemented 15 g/L with a similar yield (0.47 g/g). In addition, a higher bio-SA yield (0.49 g/g) was achieved without adding mineral salts, which could further reduce fermentation cost. The use of minimally supplemented hydrolysate resulted in 21.1 g/L of bio-SA with a satisfactory yield (0.58 g/g) in a batch bioreactor system with an estimated 56.4% in cost savings. Conclusively, OPT bagasse hydrolysate is a nutrient-rich feedstock that can be practically utilized for bio-SA production.

Multiple crystallization as a potential strategy for efficient recovery of succinic acid following fermentation with immobilized cells

This study aimed to enhance the crystallizability of bio-based succinic acid for its efficient recovery while maintaining the end product at the highest purity. Immobilization of Actinobacillus succinogenes was initially evaluated based on three different carriers: volcanic glass, clay pebbles, and silica particles. The adsorption capacity of metabolites with a low concentration (10 g/L) and a high concentration (40 g/L) was investigated. It was demonstrated that clay pebbles adsorbed the least succinic acid (< 11 mg/g clay pebbles). The repeated batch-fermentation trials with immobilized cells highlighted that succinic acid with an average concentration of up to 36.3 g/L with a metabolite-production ratio of 3:1 (succinic acid to by-products) could be attained within 130 h. Subsequently, the purification of succinic acid through crystallization was assessed in terms of pH, temperature, crystallization time, initial succinic acid concentration and multiple recrystallization processes. Increasing the crystallization time from 6 h to 9 h afforded an improvement of 17% in the recovery of succinic acid crystals. Moreover, a fourfold concentration coefficient of the broth yielded the highest purity percentage (99.9%). The crystallization in three consecutive stages at 9 h (with a fourfold concentration coefficient) successfully improved the total recovery percentage of succinic acid from 55.0 to 84.8%.

Compatibility of utilising nitrogen-rich oil palm trunk sap for succinic acid fermentation by Actinobacillus succinogenes 130Z

In this study, the potential of oil palm trunk (OPT) sap as a sole substrate for succinic acid (SA) production was evaluated using Actinobacillus succinogenes 130Z. After OPT sap was characterised, the effects of adding carbonate, yeast extract (YE) and minerals to this medium were investigated in an attempt to develop a low-cost fermentation medium. The OPT sap alone, gave comparable SA yield and productivity (0.54 g/g and 0.35 g/L/h) to those supplemented with YE (0.50 g/g and 0.36 g/L/h) and minerals (0.55 g/g and 0.40 g/L/h). The findings showed that OPT sap has sufficient amount of nutrients for SA biosynthesis by A. succinogenes 130Z and could potentially reduce cost without requiring expensive nutrients supplementation.

Mathematical models for growth in alligator (Alligator mississippiensis) embryos developing at different incubation temperatures

A variety of model-based (growth models) and model-free (cubic splines, exponentials) equations were fitted using weighted-nonlinear least squares regression to embryonic growth data from Alligator mississippiensis eggs incubated at 30 and 33 degrees C. Goodness of fit was estimated using a chi 2 on the sum of squared, weighted residuals, and run and sign tests on the residuals. One of the growth models used (Preece & Baines, 1978) was found to be superior to the classical growth models (exponential, monomolecular, logistic, Gompertz, von Bertalanffy) and gave an adequate fit to all longitudinal measures taken from the embryonic body and embryonic mass. However, measurements taken from the head could not be fitted by growth models but were adequately fitted by weighted least squares cubic splines. Data for the stage of development were best fitted by a sum of 2 exponentials with a transition point. Comparison of the maximum growth rates and parameter values, indicated that the growth data at 30 degrees C could be scaled to 33 degrees C to multiplying the time by a scaling factor of 1.2. This is equivalent to a Q10 of about 1.86 or, after solving the Arrhenius equation, an E++ of 46.9 kJmol-1. This may be interpreted as indicating a common rate-limiting step in development at the 2 temperatures.

The energy budget of Porcellio spinicornis Say (Porcellionidae, Isopoda) under laboratory conditions

The rate of energy flow in Porcellio spinicornis was investigated in a select group of a laboratory population. The consumption, assimilation and production were calculated to be 1 233, 1 002 and 304 cal/year, respectively, in the male, and 1 261, 1 198 and 429 cal/year, respectively, in the female. Ignoring loss due to mortality, and applying the population density of 2 295 m2 in the laboratory colony, the isopod population should consume 2 861.8 kcal m-2 year-1, resulting in an assimilation of 2 524.5 kcal m-2 year-1 and a total productivity of 841.1 kcal m-2 year-1.