Fermentative Acid Production Research Articles

Kinetic study on ferulic acid production from banana stem waste via mechanical extraction

Banana is the tropical plants associated with lots of medicinal properties. It has been reported to be a potential source of phenolic compounds such as ferulic acid (FA). FA has excellent antioxidant properties higher than vitamin C and E. FA also have a wide range of biological activities, such as antioxidant activities and anti-microbial activities. This paper presents an experimental and kinetic study on ferulic acid (FA) production from banana stem waste (BSW) via mechanical extraction. The objective of this research is to determine the kinetic parameters in the ferulic acid production. The banana stem waste was randomly collected from the local banana plantation in Felda Lepar Hilir, Pahang. The banana stem juice was mechanically extracted by using sugarcane press machine (KR3176) and further analyzed in high performance liquid chromatography. The differential and integral method was applied to determine the kinetic parameter of the extraction process and the data obtained were fitted into the 0th, 1st and 2nd order of extraction process. Based on the results, the kinetic parameter and R2 value from were 0.05 and 0.93, respectively. It was determined that the 0th kinetic order fitted the reaction processes to best represent the mechanical extraction.

Nitrogen removal enhancement using lactic acid fermentation products from food waste as external carbon sources: Performance and microbial communities

In this study, nitrogen removal using the lactic acid fermentation products from food waste and other external chemical carbon sources (sodium acetate, sodium lactate and starch) was investigated. Similar to sodium acetate and lactate, the lactic acid-enriched fermentation liquid from food waste (FLFW) exhibited a high denitrification rate (5.5 mg NOx-N/(g-VSS h)) and potential (0.16 g NO3−-N/g COD), and could achieve high NH4+-N and total nitrogen (TN) removal efficiencies during long-term operation. Using FLFW as supplementary carbon sources reduced the extracellular polymeric substances (EPS) content, improved the settleability and achieved a satisfactory biomass yield of activated sludge. Additionally, the increased microbial metabolic activity and bacterial community diversity and the accumulation of unique bacteria in the activated sludge cultured with FLFW further promoted the organics utilization rate and nitrogen removal efficiency, indicating that the FLFW prepared from solid waste was an ideal carbon source for wastewater treatment.

Heterologous expression of two Aspergillus niger feruloyl esterases in Trichoderma reesei for the production of ferulic acid from wheat bran.

Feruloyl esterase (FAE)-encoding genes AnfaeA and AnfaeB were isolated from Aspergillus niger 0913. For overexpression of the two genes in Trichoderma reesei, constitutive and inductive expression plasmids were constructed based on parental plasmid pAg1-H3. The constructed plasmids contained AnfaeA or AnfaeB gene under the control of glyceraldehyde-3-phosphate dehydrogenase A gene (gpdA) promoter (from A. nidulans) or cellobiohydrolases I (cbh I) gene promoter (from T. reesei), and cbh I terminator from T. reesei. The target plasmids were transferred into T. reesei D-86271 (Rut-C30) by Agrobacterium tumefaciens-mediated transformation (ATMT), respectively. A high level of feruloyl esterase was produced by the recombinant fungal strains under solid-state fermentation, and the cbh I promoter was more efficient than the gpdA promoter in the expression of AnfaeA. The optimum temperatures and pH values were 50°C and 5.0 for AnFAEA, and 35°C and 6.0 for AnFAEB. The maximum production levels were 20.69 U/gsd for AnFAEA and 15.08 U/gsd for AnFAEB. The recombinant fungal enzyme systems could release 62.9% (for AnFAEA) and 52.2% (for AnFAEB) of total ferulic acids from de-starched wheat bran, which was higher than the 46.3% releasing efficiency of A. niger 0913. The supplement of xylanase from T. longibrachiatum in the enzymatic hydrolysis led to a small increment of the ferulic acids release.

Loop of Streptomyces Feruloyl Esterase Plays an Important Role in the Enzyme's Catalyzing the Release of Ferulic Acid from Biomass.

Feruloyl esterases (FAEs) are key enzymes required for the production of ferulic acid from agricultural biomass. Previously, we identified and characterized R18, an FAE from Streptomyces cinnamoneus NBRC 12852, which showed no sequence similarity to the known FAEs. To determine the region involved in its catalytic activity, we constructed chimeric enzymes using R18 and its homolog (TH2-18) from S. cinnamoneus strain TH-2. Although R18 and TH2-18 showed 74% identity in their primary sequences, the recombinant proteins of these two FAEs (recombinant R18 [rR18] and rTH2-18) showed very different specific activities toward ethyl ferulate. By comparing the catalytic activities of the chimeras, a domain comprised of residues 140 to 154 was found to be crucial for the catalytic activity of R18. Furthermore, we analyzed the crystal structure of rR18 at a resolution of 1.5 Å to elucidate the relationship between its activity and its structure. rR18 possessed a typical catalytic triad, consisting of Ser-191, Asp-214, and His-268, which was characteristic of the serine esterase family. By structural analysis, the above-described domain was found to be present in a loop-like structure (the R18 loop), which possessed a disulfide bond conserved in the genus Streptomyces Moreover, compared to rTH2-18 of its parental strain, the TH2-18 mutant, in which Pro and Gly residues were inserted into the domain responsible for forming the R18 loop, showed markedly high kcat values using artificial substrates. We also showed that the FAE activity of TH2-18 toward corn bran, a natural substrate, was improved by the insertion of the Gly and Pro residues.IMPORTANCEStreptomyces species are widely distributed bacteria that are predominantly present in soil and function as decomposers in natural environments. They produce various enzymes, such as carbohydrate hydrolases, esterases, and peptidases, which decompose agricultural biomass. In this study, based on the genetic information on two Streptomyces cinnamoneus strains, we identified novel feruloyl esterases (FAEs) capable of producing ferulic acid from biomass. These two FAEs shared high similarity in their amino acid sequences but did not resemblance any known FAEs. By comparing chimeric proteins and performing crystal structure analysis, we confirmed that a flexible loop was important for the catalytic activity of Streptomyces FAEs. Furthermore, we determined that the catalytic activity of one FAE was improved drastically by inserting only 2 amino acids into its loop-forming domain. Thus, differences in the amino acid sequence of the loop resulted in different catalytic activities. In conclusion, our findings provide a foundation for the development of novel enzymes for industrial use.

The phenylpropanoid pathway affects apple fruit resistance to Botrytis cinerea

AbstractApple fruits are rich in phenolic compounds that may enhance resistance to grey mould disease caused by Botrytis cinerea. Using Malus domestica Borkh. cultivars Fuji and Qinguan, we analysed the contents of total phenols, total flavonoids, eight individual phenolic compounds, H2O2 and O2.− as well as the activities of key enzymes in the phenylpropanoid pathway in the flesh of control and B. cinerea‐inoculated fruits. Chlorogenic acid contents increased for a short period in the less susceptible cultivar Qinguan fruits, but decreased in the disease‐susceptible Fuji fruits. Additionally, ferulic acid production was induced in both cultivars in response to B. cinerea. Furthermore, the activities of phenylalanine ammonia lyase, cinnamate 4‐hydroxylase, 4‐coumarate:coenzyme A ligase and cinnamyl alcohol dehydrogenase were differentially induced between the two apple cultivars. Remarkably, the contents of H2O2 and O2.− as well as the activities of enzymes in phenolic metabolism tested in this study were always higher in Qinguan fruits than in Fuji fruits. Our data imply that phenylpropanoid metabolism is closely associated with apple fruit resistance to grey mould disease. These findings may be useful for characterizing the mechanism(s) underlying plant resistance to B. cinerea, with potential implications for the screening of grey mould disease‐resistant apple varieties in breeding programmes.

A Method for Ferulic Acid Production from Rice Bran Oil Soapstock Using a Homogenous System

Ferulic acid (FA) is widely used as an antioxidant, e.g., as a Ultraviolet (UV) protectant in cosmetics and in various medical applications. It has been produced by the hydrolysis of γ-oryzanol found in rice bran oil soapstock. In this study, the base-catalyzed, homogenous hydrolysis of γ-oryzanol was conducted using various ratios of potassium hydroxide (KOH) to γ-oryzanol, initial concentrations of γ-oryzanol in the reaction mixture, and ratios of ethanol (EtOH) (as cosolvent)/ethyl acetate (EtOAc) (γ-oryzanol solution). Acceleration of the reaction using a planar type of ultrasound sonicator (78 and 130 kHz) at different reaction temperatures was explored. By using a heating method, the 80% yield of FA was attained at 75 °C in 4 h under homogeneous conditions (initial concentration of γ-oryzanol 12 mg/mL, the KOH/γ-oryzanol ratio (wt/wt) 10/1, and EtOH/EtOAc ratio (v/v) 5/1). With the assistance of 78 and 130 kHz irradiation, the yields reached 90%. The heating method was applied for the γ-oryzanol-containing extract prepared from rice bran oil soapstock. From soapstock, the 74.3% yield of FA was obtained, but 20% of the trans-FA in the reaction mixture was transformed into cis-form within one month.

Metabolite profile of koji amazake and its lactic acid fermentation product by Lactobacillus sakei UONUMA

The koji amazake is a traditional sweet Japanese beverage. It has been consumed for over a thousand years in Japan; nonetheless, little is yet known of the ingredients in koji amazake. Therefore, this study aimed to analyze the metabolites of koji amazake using a metabolomics approach. Additionally, we reformed the flavor of koji amazake by lactic acid fermentation (LAF-amazake) using Lactobacillus sakei UONUMA, which was isolated from snow caverns. The purpose of this article is to identify the ingredients in these beverages. In LAF-amazake and koji amazake, sugars, amino acids, organic acids, and vitamin B complex were determined in the two beverages, and over 300 compounds were detected in total. Thirteen saccharides were identified including two unknown trisaccharides, and there were no differences in these between the two beverages. In LAF-amazake, lactic acid, vitamin B2 (riboflavin), B3 (nicotinic acid and nicotinamide), and B6 (pyridoxine) were significantly increased as compared to koji amazake, whereas malate and glutamine decreased. These results suggested that LAF, malolactic fermentation, and glutamine deamidation occurred simultaneously in LAF-amazake. L.sakei UONUMA strains produced these vitamins. Moreover, it was surprising that acetylcholine, a well-known neurotransmitter, was newly generated in LAF-amazake. Here, we have succeeded in reforming the flavor of koji amazake and obtained these metabolic data on the two beverages. The present study could provide useful basic information for promoting functional analyses of koji amazake and LAF-amazake for human health.

Optimization of ferulic acid production from banana stem waste using central composite design

Abandoning banana stem waste (BSW) seems a loss since it is a good source of lignocelluloses to produce ferulic acid (FA). This study was conducted to optimize the production of FA via feruloyl polysaccharide hydrolysis from BSW by fermentation with a soil mixed culture. The optimization used response surface methodology (RSM) based on a five level‐two factor central composite design (CCD). Parameters studied were the ratio of water to BSW (v/v) and incubation time (hours). Range values for each factor were 0.5:1 to 1.5:1 ratio and 12–36 h, respectively. Interaction between these factors revealed that effect of time was greater than ratio of water to BSW, since a sufficient time is important for the mixed culture to fully use BSW during inoculation. The optimum condition was determined as 1:1 water to BSW ratio and 27 h incubation time. Under this optimized condition, the maximum FA produced was 1.17 mg FA/g BSW, which was in close agreement with predicted values (30%). This indicates that the suitability of the models was successfully developed by RSM‐CCD in optimizing the hydrolysis conditions for maximum FA production. That being said, BSW is proven useful and highly feasible for producing quality goods naturally. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1217–1223, 2017

MSG 첨가 비율을 달리한 섬애약쑥(Artemisia argyi H) 식혜의 유산균 발효에 따른 이화학적 특성

For the production of γ-aminobutyric acid (GABA) contents increased Seomaeyaksuk fermentant, 0, 0.25, 0.5 and 1.0% of monosodium galutamate (MSG) was added in Seomaeyaksuk water extract 15% contained Sikhye and inoculated with Lactobacillus brevis (KI271266). Physicochemical properties were sampling and analyzed at each 1 day during 3 days fermentation. Goes on fermentation periods, the turbidity was gradually reduced, but lightness and the yellowness was increased, redness was decreased. Soluble solid was also decreased. The reducing sugars content were also decreased during fermentation. pH was 4.65-4.83 before fermentation but it was lower 3.15-3.68 after three days fermentation. The GABA contents increased by fermentation periods and it was the highest in MSG 1.0% added sample (354.38 mg/L). Fructose, glucose and sucrose contents were 50-67% decreased at three days fermentation than before fermentation. Among the organic acids, propionic acid, oxalic acid, citric acid and fumaric acid contents were decreased and lactic acid, acetic acid and succinic acid were increased during fermentation periods. Contents of total polyphenol and DPPH radical scavenging activity were the highest in MSG 0.5% added sample. From these results, we confirmed that increasing of GABA content when the manufacturing of Seomaeyaksuk lactic acid fermentation product, is possibile by addition of MSG without affecting physicochemical characteristics.

Elicitation of Phenylpropanoids and Expression Analysis of PAL Gene in Suspension Cell Culture of Ocimum tenuiflorum L.

The accumulation of total phenylpropanoids and the real time expression of PAL genes in Ocimum tenuiflorum suspension cell cultures were investigated. A comprehensive analysis of the effects of various abiotic elicitors like jasmonic acid (JA), methyl jasmonate (MeJA), salicylic acid (SA) and precursor feeder L-phenylalanine (L-phe) was done in O. tenuiflorum suspension cell cultures during elicitation. Ultra performance liquid chromatography based metabolite profiling revealed differential accumulation of three pharmaceutically important phenylpropanoids: caffeic acid, vanillin and ferulic acid. This accumulation corroborated well with real time expression of PAL genes. Biomass analysis during elicitation showed L-phe and JA moderately and MeJA and SA marginally affected the cell growth. Single and repetitive feeding with L-phe induced 22.5 fold accumulations in caffeic acid, ferulic acid and vanillin on day 16 with PAL expression increasing by 9.8–12 fold. SA (1.5 mM) induced 61 fold increase in caffeic acid accumulation with PAL expressions raised by 4.5 fold. MeJA at 25 µM promoted ferulic acid production up to 62 fold having PAL expression raised by seven fold on day 16 of elicitor treatment. Enhanced accumulation of total phenylpropanoids and elevated expression of PAL gene were observed during the course of treatment with elicitors and precursor feeder. This stipulates that PAL may modulate the biosynthesis of phenylpropanoids especially vanillin, caffeic acid and ferulic acid. The present study is of particular significance for using suspension cell culture systems of O. tenuiflorum, a less explored plant, for biotechnological production of pharmaceutically important plant secondary metabolites.

Effects of agitation and volume of inoculum on ferulic acid production by co-culture

Response surface methodology (RSM) has been known as the best tool in evaluating the effects of several variables and their interactions of biochemical and biotechnological processes. The main focus of this research was to study the effects of agitation and volume of inoculum in influencing the ferulic acid production from banana stem waste by co-culture. The optimum conditions for the production process were also determined. RSM with five replicates at the center point was performed to evaluate the contribution of the factors. The p-values of 0.0249 and 0.0268 for agitation and volume of inoculum, respectively, indicate the importance of both factors in ferulic acid yield. Agitation at 150 rpm and volume of inoculum of 5% were found optimum in increasing the ferulic acid yield up to 510.24 mg/kg within 24 h. The results demonstrate that the use of RSM is very helpful to study the effects of interactions among the parameters for efficient production of biological products.

On the ecosystemic network of saliva in healthy young adults

A dysbiotic state is believed to be a key factor in the onset of oral disease. Although oral diseases have been studied for decades, our understanding of oral health, the boundaries of a healthy oral ecosystem and ecological shift toward dysbiosis is still limited. Here, we present the ecobiological heterogeneity of the salivary ecosystem and relations between the salivary microbiome, salivary metabolome and host-related biochemical salivary parameters in 268 healthy adults after overnight fasting. Gender-specific differences in the microbiome and metabolome were observed and were associated with salivary pH and dietary protein intake. Our analysis grouped the individuals into five microbiome and four metabolome-based clusters that significantly related to biochemical parameters of saliva. Low salivary pH and high lysozyme activity were associated with high proportions of streptococcal phylotypes and increased membrane-lipid degradation products. Samples with high salivary pH displayed increased chitinase activity, higher abundance of Veillonella and Prevotella species and higher levels of amino acid fermentation products, suggesting proteolytic adaptation. An over-specialization toward either a proteolytic or a saccharolytic ecotype may indicate a shift toward a dysbiotic state. Their prognostic value and the degree to which these ecotypes are related to increased disease risk remains to be determined.

Towards Biorefinery Production of Microalgal Biofuels and Bioproducts: Production of Acetic Acid from the Fermentation of <i>Chlorella</i> sp. and <i>Tetraselmis suecica</i> Hydrolysates

Successful commercialization of microalgal bio-industry requires the design of an integrated microalgal biorefinery system that facilitates the co-production of biofuels, high-value products and industrial chemicals from the biomass. In this study, we investigated the use of sugar hydrolysate obtained from enzymatic saccharification of microalgal biomass (Chlorella sp. and T. suecica) as fermentation feedstock to produce industrially important chemicals, in particular acetic acid and butyric acid. By using hydrolysate with low sugar content as substrate for the anaerobic fermentation (1.5 - 2.4 g/L), we were able to prevent the bacterium C. saccharoperbutylacetonicum from activating its solventogenesis pathway. As a result, the fermentation process generated a product stream that was dominated by organic acids (acetic acid and butyric acid) rather than solvents (butanol, ethanol and acetone). Acetic acid constituted up to 92 wt% of Chlorella’s fermentation products and 80 wt% of T. suecica’s fermentation products. For T. suecica, the fermentation consumed almost all of the sugar available in the hydrolysate (up to 92% of initial sugar) and produced a reasonable yield of fermentation products (0.08 g fermentation products/g sugar). The Gompertz equation was successfully used to predict the formation kinetics of acetic acid and other fermentation products across both species. The results in the study demonstrate the production of industrially important chemicals, such as acetic acid and butyric acid, from the fermentation of microalgal sugar. The process described in the study can potentially be used as a value-adding step to generate biochemicals from cell debris in an integrated microalgal biorefinery system.

High Benzoic Acid Production in a Grape-Based Ayurvedic Medicinal Wine (ASAVA)

Fermentative production of benzoic acid is seldom reported and the present report serendipitously expressed it, though in small quantity (~30 mg/l). Lipoxygenases (LOXs) catalyse the stereo-specific insertion of molecular oxygen into arachidonic acid, leading to hydroxy derivatives as end products. Ser-endipitously found LOX inhibitor was benzoic acid, produced in Ayurvedic-fermented medicated wine, pippalyasava. The present study reports the signifi-cance of the polyphenol derivatives in a traditional Ayurvedic therapeutic preparation where LOX inhibi-tion might have a role, besides its importance in fermented benzoic acid production.

Open Fermentative Production of L-Lactic Acid from Distillers’ Grains by Lactobacillus casei CICC 6056

Distillers’ grains (DG) are potential fermentable sugar substrates for the production of value-added products. This study focused on the development of an open fermentation process for the production of L-lactic acid from DG using Lactobacillus casei CICC 6056. The open fermentation process was feasible, resulting in an L-lactic acid yield similar to that obtained with sterilized fermentation. However, a decrease in pH below 5.0 after 24 h resulted in a poor L-lactic acid concentration of 9.18 g/L and an inferior reducing sugar conversion rate of 53.6%. Therefore, an optimal pH adjustment method was sought. A pH adjustment to 6.5 every 24 h effectively improved the L-lactic acid concentration to 21.3 g/L with a 97.8% reducing sugar conversion rate. Furthermore, the application of a simultaneous saccharification and fermentation process at 50 °C in open condition increased the L-lactic acid concentration to 25.0 g/L. This yield was superior to L-lactic acid fermentation from DG using a separate hydrolysis and fermentation method (21.3 g/L) and from a commercial sugar in batch culture (23.6 g/L). These results demonstrated that L. casei CICC 6056 has great industrial potential as a superior candidate strain for the production of L-lactic acid from DG due to its broad applicability in a wide temperature range (from 37 to 50 °C).

An unusual feruloyl esterase from Aspergillus oryzae: two tryptophan residues play a crucial role for the activity

The genome of Aspergillus oryzae encodes a hypothetical protein (annotated as AO090701000884), designated AoFaeD, which exhibits sequence identity to feruloyl esterases from Aspergillus clavatus, Coprinopsis cinerea, Neurospora crassa, and Pseudomonas fluorescens subsp. cellulosa. In this study, we cloned the AofaeD coding sequence into Pichia pastoris and demonstrated heterologous expression and secretion of active recombinant enzyme (rAoFaeD) as a 30-kDa protein in the culture medium. Purified rAoFaeD exhibited optimal activity at pH 7.0 and at 45°C, but was stable at a pH range of 7.0–10.0 and a temperature of 40°C. While wild-type rAoFaeD failed to cleave the methyl esters of ferulic acid (MFA), p-coumaric acid (MpCA), caffeic acid (MCA), and sinapic acid (MSA) and ethyl ester of ferulic acid (EFA), enzyme exhibited esterase activity when wheat arabinoxylan was used as a substrate, and this reaction was enhanced synergistically by the addition of xylanase. Notably, rAoFaeD variants in which one of the tryptophan residues (Trp142 or Trp144) located adjacent to the putative catalytic serine residue at position 143 (Ser143) was replaced with phenylalanine and tyrosine (W142F and W144Y), respectively, exhibited hydrolytic activity toward MFA, MpCA, MCA, MSA, and EFA. Moreover, these variants exhibited enhanced production of ferulic acid from wheat arabinoxylan compared to the wild-type protein, and the activity of these proteins was enhanced by the addition of xylanase.

The use of factorial design for ferulic acid production by co-culture

Several factors can influence the use of co-culture for ferulic acid production from banana stem waste. The aim of this study was to analyse factors of temperature, pH, agitation, water-to-substrate ratio, volume of inoculum, fermentation time, and type of co-culture by employing a 24 fractional factorial design (FFD). The results showed the order of contribution effects towards ferulic acid production: pH>type of co-culture>volume of inoculum>agitation>fermentation time>temperature>water-to-substrate ratio. Four factors including pH, agitation, type of co-culture, and volume of inoculum were shown to have significant effects on ferulic acid production. Among the determining factors, the main factor of pH and the interaction of temperature and fermentation time had the strongest effect on ferulic acid production. The result indicated that FFD was useful to improve the ferulic acid production by considering all the interactions of variables involved.

Antioxidant activity of liquid cultured Inonotus obliquus polyphenols using tween-20 as a stimulatory agent: Correlation of the activity and the phenolic profiles

Polyphenols are major functional components of the medicinal mushroom Inonotus obliquus. Compared with the wide application of surfactants in medicinal mushroom polysaccharide production, using surfactants to enhance mushroom polyphenol production and antioxidant activity is a relatively new approach. For the first time, in the present study, we evaluated the effect of Tween-20 on the growth-associated generation of different compositions and antioxidant activity expression of exo-polyphenol product (EPC) and endo-polyphenol product (IPC) of liquid cultured I. obliquus. The IC50 values against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals of EA-EPC, NB-EPC, and IPC from the Tween-20 (5.0g/l on Day 1) adding medium were between 40 and 47mg/l, significantly (p < 0.05) lower than the control group (96–112mg/l). Phenolic acids, i.e., ferulic acid and gallic acid, and flavonoids, i.e., epicatechin-3-gallate (ECG), epigallocatechin-3-gallate (EGCG), and naringin, were the main components in EPC and IPC analyzed by HPLC. The production of ferulic acid, ECG, EGCG, and naringin was significantly increased by 106.0%, 157.7%, 37.3%, 75.2% in EA-EPC, 372.9%, 133.7%, 117.3%, 19.4% in NB-EPC, and 10.4%, 102.7%, 57.7%, 322.2% in IPC. The antioxidant activity expression of EA-EPC, NB-EPC, and IPC from both the control and Tween-20 media was highly correlated with the growth-associated generation of these flavonoids during fermentation. The significantly higher antioxidant activity of EPC and IPC from the Tween-20 medium compared with the control was also attributed to the higher content of the flavonoids. The strategy of supplementation of surfactants has the potential for other medicinal mushroom fermentation processes to enhance the production of highly bioactive flavonoids.

A FACTORIAL ANALYSIS STUDY ON FACTORS CONTRIBUTION TO FERULIC ACID PRODUCTION FROM OIL PALM FROND WASTE

Enzymatic hydrolysis of fibre-pressed oil palm frond (FPOPF) was done using mix culture for the production of ferulic acid. Mix culture was prepared by acclimatizing the soil obtained from palm oil plantation with FPOPF substrate for 30 days. The substrate had a ratio of FPOPF to water of 1:10. Design Expert 7.1 was used to aid the experimental design. A half fractional two-level factorial analysis with five factors was selected for the experimental design resulting in a total of 16 runs. The factors controlled were temperature (A; 26°C and 40°C), pH value (B; 5 and 9), agitation speed (C; 0 and 150 rpm), inoculum percentage (D; 2% and 10%), and response time (E; 1 and 3 days). The result obtained showed that the experimental design model was significant with a coefficient of determination value of 0.8978. Two factors that contributed the most to the process were temperature and pH value. This model was proved to be repeatable with a validation test percentage error at 4.15% to 6.83%.

Relative fermentation of oligosaccharides from human milk and plants by gut microbes

Gut microbiota is important to human health. Specific dietary glycans promote favorable microbiota growth and inhibit pathobionts. Dietary glycans most relevant to adults and weaned infants are derived from plants or lactose; human milk oligosaccharides (HMOS) are most relevant to breastfed infants. Their efficacy in supporting bacterial growth is compared to determine their potential roles in the initiation and maintenance of colonization. Bioactivities of gluco-manno-oligosaccharides (GMOS), galacto-oligosaccharides (GOS), xylo-oligosaccharides (XOS), cellobiose (CBS), HMOS, and the most prominent individual HMOS, 2′-fucosyllactose (2′-FL) were contrasted. Two representative gut microbiota mutualists, Bifidobacteria longum ATCC15697 and Lactobacillus acidophilus NRRL B-4495, and two non-mutualists, Campylobacter jejuni S107 and Escherichia coli K12, were used to assess the in vitro prebiotic potential of these oligosaccharides. All oligosaccharides afforded growth of B. longum and L. acidophilus, with HMOS supporting the most robust growth, while none of these oligosaccharides afforded meaningful growth of non-mutualists. B. longum efficiently converted HMOS, GMOS, GOS, and XOS into organic acid fermentation products, and, to a lesser degree, L. acidophilus metabolized HMOS, GMOS, and GOS. Fermentation of these glycans by C. jejuni and E. coli was sparse. B. longum fermentation products inhibited C. jejuni and E. coli. Thus, HMOS most strongly promoted growth of the two mutualists, and both HMOS and GMOS were efficiently fermented by these mutualists into organic acids. This is consistent with a primary role of HMOS in guiding early colonization of the infant microbiota by mutualist symbionts, and of plant oligosaccharides, especially GMOS, in maintaining a favorable microbiota through adulthood.