Fermentation pH Research Articles

Propionic acid production from glycerol in immobilized cell bioreactor using an acid-tolerant strain of Propionibacterium acidipropionici obtained by adaptive evolution

Propionic acid (PA) production from agro-industrial residues using propionibacteria has gained interest as an alternative to fossil-based process. Microbial production is however characterized by product inhibition, lowering the product titers and productivity. In this study, Propionibacterium acidipropionici DSMZ4900 was subjected to adaptive evolution to tolerate higher acid concentrations. The strain adapted to growth in medium spiked with 20 g/L PA exhibited improved product titer (16.8 vs 8.72 g/L) and productivity (0.52 vs 0.17 g/L·h) with glycerol as carbon source in batch fermentations. It was immobilized on polyethyleneimine coated recycled glass beads Poraver® and used for fermentations in recycle batch mode with increasing glycerol concentration and decreasing pH, respectively. Doubling yeast extract concentration raised PA yield and productivity by >1.5 fold. Glycerol at 100 g/L was completely consumed to give ∼58 g/L PA at yield of 0.64 mol/mol and productivity of 0.28 g/L·h at pH 6.5. Decreasing fermentation pH to 5.0 increased PA productivity to 0.23 g/L·h from 0.14 g/L·h at pH 6.0 with 20 g/L glycerol, while immobilized cells exhibited no growth. The study shows combination of adaptive evolution and immobilization of cells to result in a robust system for PA fermentation at high glycerol concentration and lower pH.

Assessing the potential use of a feed additive based on biochar on broilers feeding upon productive performance, pH of digestive organs, cecum fermentation and bacterial community

This study was conducted to assess the influence of supplementing broiler diets with a commercial biochar on productive performance, pH of digestive organs, cecum short chain fatty acid (SCFA) profile and bacterial community. 720 one day-old male Ross 308 broilers were fed with the following diets at starter (1–21 days) and grower-finisher period (22–42 days): control diet (0 g/kg of inclusion on diet of biochar, CTR) or 30 g/kg of inclusion of biochar. Regarding performance results, at the starter period animals fed a diet with biochar showed lower daily weight gain (DWG, P = 0.045) and higher feed conversion ratio (FCR, P = 0.034) but similar feed intake (FI, P = 0.928) compared to CTR. At the grower-finisher period, feeding broilers with biochar promoted an increase on DWG (P < 0.001) and a reduction on FCR (P < 0.001) with similar FI (P = 0.579) compared to CTR. For the entire period of feeding, animals fed with biochar showed an increased DWG (P < 0.001), body weight (P < 0.001) and European production efficiency factor (P < 0.001), a reduced FCR (P < 0.001) and a similar FI (P = 0.577) compared to CTR. Regarding digesta pH of digestive organs the pH of digesta of crop (P = 0.834), proventriculus (P = 0.846), gizzard (P = 0.850), ileum (P = 0.750) or cecum (P = 0.467) were not affected by biochar. Animals fed with biochar showed increased acetic (P = 0.011) and caproic (P = 0.003) contents, and similar propionic (P = 0.724), butyric (P = 0.568), isobutyric (P = 0.436), valeric (P = 0.898) and isovaleric (P = 884) contents compared to CTR. Biochar did not influence cecal bacterial species richness and diversity but altered community structure by increasing relative abundance of [Ruminococcus], Ruminococcus, Blautia and undefined genera (family Ruminococcaceae, Lachnospiraceae and Erysipelotrichaceae) and decreasing Lactobacillus, Coprococcus, Desulfotomaculum, Oscillospira, Clostridium (family Clostridiaceae) and undefined genera (families Lachnospiraceae and Ruminococcaceae). In conclusion although the inclusion on diet of 30 g/kg biochar reduced the productive performance during the starter phase, an enhanced growth of animals during the grower-finisher period was observed, resulting in a greater performance and efficiency of production for the entire cycle without affecting the pH of digestive organs and increasing acetate contents in the caecum. The greater performance could be explained by minor microbiota shifts observed at OTU (Operational Taxonomic Unit) level without disturbing the native beneficial intestinal bacteria as expressed by the retained richness and diversity of the broilers caecal microbiota.

Screening and identifying microorganisms with feruloyl esterase activity in Chinese sesame-flavour baijiu fermentation materials (Jiupei)

Baijiu is a national beverage in China. Some functional compounds have been identified in baijiu, one of which is ferulic acid. One route for in situ ferulic acid synthesis is catalysed by feruloyl esterase from microorganisms using baijiu raw materials as substrates. However, few studies have focused on microorganisms obtained from baijiu that have feruloyl esterase activity. In this work, microorganisms with feruloyl esterase activity were screened in the fermented raw materials of baijiu. Four different microorganisms with feruloyl esterase activity were identified, and one strain, designated J1, showed high feruloyl esterase activity. The strain J1 belonged to the genus Acetobacter and showed the closest relationship with Acetobacter fabarum and Acetobacter lovaniensis. The feruloyl esterase production capacity of J1 was confirmed, and the fermentation conditions were optimised. The optimal enzyme production conditions for the highest feruloyl esterase activity required an initial fermentation pH of 7.0 at 30 °C, an inoculation volume of 10 %, and culturing for 24 h.

Studies on Bioethanol Production with Thermo Tolerant Yeast Isolates and their Co-Cultures using African Wild Cocoyam as Feedstock

In this work different ways of optimally producing bioethanol at various pH with thermotolerant yeasts and their cocultures using a non-human edible starchy food as feedstock was examined. African wild cocoyam, Xanthosoma roseum, sourced from abandoned farmlands in Obukpa, Nsukka, Nigeria was used as the substrate, while strains of Kluyveromyces marxianus and Pichia stipitis were used to ferment them. First the tubers were gelatinized by boiling under pressure above 100oC before hydrolysis with concentrated H2SO4. The hydrolysates were then fermented at 35oC with the thermotolerant yeasts for five days at different pH. Results obtained showed that gelatinized sample of the substrate gave optimum glucose yield when hydrolysed with 1M H2SO4 for 60 minutes. Kluyveromyces marxianus produced more ethanol than Pichia stipitis at all the four fermentation pH values tested. However, optimum ethanol production was obtained when the two yeast strains were used as coculture at pH 4.5. The peak time for ethanol production was 96 hours for the individual yeast cultures while that of their coculture was 72 hours. The results of the study indicated that wild cocoyam is an excellent feedstock for bioethanol production with many advantages including being non-edible, thereby eliminating concerns for food security, and containing high amount of carbohydrate. The study also revealed that fermenting sugar hydrolysates with a coculture of microorganisms during bioethanol production is a more efficient process than using individual cultures.

Possibility of wine production from karanda (Carissa carandas L.) fruit

Karanda (Carissa carandas L.) is an underutilized fruit with plenty therapeutic and functional properties. In fermentation, yeast metabolites soluble solids in fruit juice to produce energy, ethanol and carbon dioxide. The present research aimed to examine various parameters such as temperature, pH, sugar addition and inoculum size in the primary fermentation, and aging time in storage affecting to karanda wine quality. This research was conducted from 2019 to 2020. Results showed that supplementation of sugar 9 %, pH 3.6, temperature 28 oC, inoculum size 14% and aging in 10 weeks, karanda wine obtained high ethanol content (8.19±0.02 % v/v), total phenolic content (184.32±1.17 mg GAE/100 g) and overall acceptability (8.01±0.02). Wine from this valuable karanda fruit would be beneficial for health by moderate consumption.

Effect of Rye Grain Derived from Different Cultivars or Maize Grain Use in the Diet on Ruminal Fermentation Parameters and Nutrient Digestibility in Sheep

Abstract Six wether sheep with ruminal and duodenal cannulas were used in a replicated 3 × 3 Latin square to determine the effect of rye grain (from an open-pollinated or a hybrid cultivar) and maize grain from hybrid cultivar inclusion in the diet on ruminal fermentation parameters and nutrient digestion in different gastrointestinal tract compartments. The experimental diets consisted of meadow hay (800 g/day) and a concentrate mixture (300 g/day) that contained rye grain from an openpollinated cultivar (OPRG), rye grain from a hybrid cultivar (HRG), or maize grain from a hybrid cultivar (MG) as a main energy source. Each experimental period lasted 17 days and consisted of 10 days for diet adaptation and 7 days for data and sample collection. Ruminal fermentation (pH, short-chain fatty acids, and ammonia concentration) and nutrient digestion up to the duodenum (in reticulorumen, omasum, and abomasum), in the intestine, as well as in the total digestive tract was investigated. Mean ruminal pH was higher for MG compared to HRG and OPRG (P&lt;0.01) but did not differ between HRG and OPRG (6.45, 6.35, and 6.29 for MG, HRG, and OPRG, respectively). Treatment did not affect short-chain fatty acid concentration in the rumen, except for the molar proportions of valeric acid and of isovaleric acid of the total short-chain fatty acids, which was or tended to be higher (P≤0.06) for MG compared to HRG and OPRG. Less starch was digested in the gastrointestinal tract up to the duodenum and more in the intestine for MG compared to HRG and OPRG (P=0.01); however, total tract nutrient digestibility did not differ between treatments. In conclusion, usage of rye grain in sheep diets resulted in a lower ruminal pH compared to maize grain usage. No differences for ruminal fermentation, nutrient digestion up to the duodenum, in the intestine, as well as in the total digestive tract between rye grain from open-pollinated and hybrid cultivar usage in sheep diets were found.

Study on Processing Technology of Pickled Radish

The work aimed at the effects of salt, soybean oligosaccharide and perilla-bean sprout juice on pH, nitrite content and sensory quality during fermenting. On this basis, the effects of different proportion of lactic acid bacteria and yeast on the dynamic changes in the total number of lactic acid bacteria and the total number of yeast of fermentation broth, pH, nitrite content and sensory quality of pickled radish were studied. The results showed that the comprehensive effect of 4% salt, 5% soybean polysaccharide and 4% perilla-bean sprout juice was the best, the pH of pickled radish was 3.36, the content of nitrite was 1.5 mg/kg, and the sensory score was 78.7. Compared with natural fermentation, adding 0.2 g lactic acid bacteria powder and 0.2 g yeast powder for seven days, the lactic acid bacteria and yeast concentration of pickled radish reached 108.05 CFU/mL and 106.68 CFU/mL, respectively, the pH was 3.27, the nitrite content was 1.1 mg/kg, and the comprehensive sensory score was 79.1. The results of this study expanded the path to improve the processing technology of pickled radish with low sodium salt and low nitrite.

Process optimization for enhanced production of cellulases form locally isolated fungal strain by submerged fermentation

Cellulase has myriad applications in various sectors like pharmaceuticals, textile, detergents, animal feed and bioethanol production, etc. The current study focuses on the isolation, screening and optimization of fungal strain through one factor at a time technique for enhanced cellulase production. In current study sixteen different fungal cultures were isolated and the culture which quantitatively exhibits higher titers of cellulase activity was identified both morphologically and molecularly by 18S rDNA and designated as Aspergillus niger ABT11. Different parameters like fermentation medium, volume, temperature, pH and nutritional components were optimized. The highest CMCase and FPase activities was achieved in 100ml of M5 medium in the presence of 1% lactose and sodium nitrate at 30 oC, pH5 after 72 hours. The result revealed A. niger can be a potential candidate for scale up studies.

Enhanced antioxidant activity of Chenopodium formosanum Koidz. by lactic acid bacteria: Optimization of fermentation conditions.

In this study, different probiotics commonly used to produce fermented dairy products were inoculated independently for Chenopodium formosanum Koidz. fermentation. The strain with the highest level of antioxidant activity was selected and the fermentation process was further optimized via response surface methodology (RSM). Lactobacillus plantarum BCRC 11697 was chosen because, compared to other lactic acid bacteria, it exhibits increased free radical scavenging ability and can produce more phenolic compounds, DPPH (from 72.6% to 93.2%), and ABTS (from 64.2% to 76.9%). Using RSM, we further optimize the fermentation protocol of BCRC 11697 by adjusting the initial fermentation pH, agitation speed, and temperature to reach the highest level of antioxidant activity (73.5% of DPPH and 93.8% of ABTS). The optimal protocol (pH 5.55, 104 rpm, and 24.4°C) resulted in a significant increase in the amount of phenolic compounds as well as the DPPH and ABTS free radical scavenging ability of BCRC 11697 products. The IC50 of the DPPH and ABTS free radical scavenging ability were 0.33 and 2.35 mg/mL, respectively, and both protease and tannase activity increased after RSM. An increase in lower molecular weight (<24 kDa) protein hydrolysates was also observed. Results indicated that djulis fermented by L. plantarum can be a powerful source of natural antioxidants for preventing free radical-initiated diseases.

Effect of Dried Distillers Grains With Solubles and Red Osier Dogwood Extract on Fermentation Pattern and Microbial Profiles of a High-Grain Diet in an Artificial Rumen System.

The objective of this study was to evaluate the effect of dried distillers grains with solubles (DDGS) and red-osier dogwood (ROD) extract on in vitro fermentation characteristics, nutrient disappearance, and microbial profiles using the rumen simulation technique. The experiment was a completely randomized design with a 2 × 2 factorial arrangement of treatments and four replicates per treatment. A basal diet [10% barley silage, 87% dry-rolled barley grain, and 3% vitamin and mineral supplement, dry matter (DM) basis] and a DDGS diet (as per basal diet with 25% of wheat DDGS replacing an equal portion of barley grain) were supplemented with ROD extract at 0 and 1% (DM basis), respectively. The experimental period was 17 d, consisting 10 days of adaptation and 7 days of data and sample collection. The substitution of wheat DDGS for barley grain did not affect gas production; disappearances of DM, organic matter, and crude protein; total volatile fatty acid (VFA) production; and microbial protein production. However, replacing barley grain with wheat DDGS increased (P = 0.01) fermenter pH and molar proportion of branched-chain VFA, switched (P = 0.06) the fermentation pattern to higher acetate production due to increased (P = 0.01) disappearance of neutral detergent fiber (NDF), and decreased (P = 0.08) methane (CH4) production. In the basal barley diet, the ROD extract increased the acetate to propionate (A:P) ratio (P = 0.08) and reduced the disappearance of starch (P = 0.06) with no effect on any other variables. No effects of ROD in the DDGS diet were observed. The number of operational taxonomic unit (OTUs) and the Shannon diversity index of the microbial community had little variation among treatments. Taxonomic analysis revealed no effect of adding the ROD extract on the relative abundance of bacteria at the phylum level with either the basal diet or DDGS diet, while at the genus level, the microbial community was affected by the addition of both DDGS and the ROD extract. Prevotella and Fibrobacter were the most abundant genera in the basal diet; however, Treponema became the most abundant genus with the addition of the ROD extract. These results indicated that the substitution of wheat DDGS for barley grain may mitigate enteric CH4 emissions. The trend of reduced starch fermentability and increased NDF disappearance with the addition of ROD extract suggests a reduced risk of rumen acidosis and an improvement in the utilization of fiber for cattle-fed high-grain diet.

The influence analysis of cow dung additional at biogas production of Palm Oil Mill Effluent (POME)

Palm Oil Mill Effluent (POME) with the anaerobic fermentation method can be converted into biogas. The aim of this study was to determine the effect of adding cow dung to biogas production from POME. This study used a pure POME and mixture of POME and cow dung. The ratio used POME mixture: Cow dung 90:10, 80:20, and 70:30. This fermentation was carried out 25 days with a digester with a volume of 10 L which was equipped with a stirrer. Before fermentation, some measurements were done, initial measurements of pH, temperature, C levels, N levels, C / N ratio and total Volatile solid (TVS) POME and also a mixture of POME and cow dung to determine the chemical properties of the two materials. During the fermentation process, pH and temperature were reduced. The biogas produced was measured on the 10th, 15th, 20th and 25th day using a Gas Chromatography. From these measurements it was found that a mixture of POME and 70:30 cow manure on the 20th day produced the greatest levels of biogas which was 300.25 ppm. whereas pure POME with the same time only produces 210.4 ppm. This means that the addition of cow dung can increase biogas production.

Optimization of Antihypertensive Peptide Preparation by Lactobacillus plantarum Fermentation of Soy Whey

To optimize the process conditions of preparation of antihypertensive peptides from the soybean whey fermented by Lactobacillus plantarum, based on the single factor, the response surface method was used and its antihypertensive activity in vitro was studied. The results of variance analysis showed that the order affecting the polypeptide yield was: the initial pH &gt; fermentation time &gt; fermentation temperature &gt; glucose addition. The model regression analysis showed that the optimal conditions for the production of antihypertensive peptides by Lactobacillus plantarum were as follows: fermentation temperature was 37 °C, fermentation time was 17 h, the initial pH of fermentation was 6.4, the amount of glucose addition was 1.50%, the polypeptide yield was 62.53% and the predicted value was 61.61%, with no significant difference (P &gt; 0.05). In vitro, antihypertensive activity results showed that the angiotensin-converting enzyme (ACE) inhibition rate of fermented soy whey peptides was 85.77%. The results provided the theoretical basis for the high-value development and utilization of soy whey.

Scale-up fermentation of Escherichia coli for the production of recombinant endoglucanase from Clostridium thermocellum

Endoglucanase (EC 3.2.1.4) catalysing the hydrolysis of β-1.4-glycosidic linkage of cellulose molecules is an enzyme of tremendous industrial importance. The present study describes a response surface methodology based predicted model to deduce a set of fermentation conditions for optimum growth and activity of recombinant endoglucanase in E. coli BL21 (DE3). Numerous significant parameters including fermentation media composition, temperature (Celsius), pH and agitation rate (rpm) were analysed systemically by employing central composite design. This effort reports highly efficient recombinant endoglucanase overproduction (6.9 gl−1 of biomass) with 30% expression by E. coli in modified M9NG media incubated at 37 °C and pH 7 agitated at 200 rpm. Addition of 3 mM glucose and 24 mM glycerol in the M9NG media has shown positive effect on the enzyme yield and activity. The CMCase activity experimentally estimated was found to be 1185 U/mg with the optimized parameters. The outcomes of both the responses by the predicted quadratic model were found in consensus with the obtained values. Our results well depicted the favourable conditions to further scale-up the volumetric yield of other relevant recombinant enzymes and proteins.

Microbial mechanism of enhancing methane production from anaerobic digestion of food waste via phase separation and pH control

Phase separation and pH control are commonly used to improve methane production during anaerobic digestion (AD) of food waste, but their influencing mechanisms have not been fully discovered through microbial analysis. In this study, single-phase AD (SPAD), two-phase AD without pH control (TPAD-pHUC), and TPAD with fermentation pH controlled at 6.0 and 4.5 were conducted. The results showed that phase separation decreased the ratio of total bacteria to total archaea in the methanogenic phase. At the organic loading rate (OLR) of 1.9 g/(L·d), methanogenesis was dominated by acetoclastic Methanosaeta in both SPAD and TPAD-pHUC, while elevated Methanoculleus and active hydrogen production initiated a shift from the acetoclastic to hydrogenotrophic pathway in SPAD as OLR increased, eventually resulting in excessive acidification at OLR 3.2 g/(L·d). TPAD-pHUC was dominated by Methanosaeta with scarce hydrogen production genes, and thus maintained a delicate balance between fewer acidogens and methanogens at OLR 3.2–3.7 g/(L·d). TPAD with pH control exhibited higher methane yield (460–482 ml/g) at OLR 1.9 g/(L·d) due to the enhancement of protein degradation and the conversion from methylated compounds to methane by Methanosarcina. High Na+ concentration facilitated the proliferation of hydrogen production bacteria, but inhibited acetoclastic methanogenesis at OLR 2.4 g/(L·d). In comparison with SPAD and pH control, TPAD without pH control, integrating 4 d acidogenesis and 22 d methanogenesis, exhibited the best and steady performance at OLR 3.7 g/(L·d) with methane production exceeding 370 ml/g.

PREDOMINANCE OF BACILLUS SPP. DURING THE PRODUCTION OF MANTCHOUA, A TRADITIONAL KAPOK SEED FERMENTED CONDIMENT FROM BURKINA FASO

Mantchoua is a fermented seed condiment produced from kapok tree (Ceiba pentandra) seeds in Burkina Faso. In this study, the microbiology of Mantchoua from raw material to final product was investigated in samples from two production sites (Pô and Bobo-Dioulasso). Four processing methods of Mantchoua production were characterized by determination of numbers of Aerobic Mesophilic Bacteria (AMB), Bacillus spp. and pH. A total of 251 Bacillus spp. from 619 AMB isolates were identified using M13-PCR and ITS-PCR typing, 16S rRNA and gyrA gene sequencing. AMB and Bacillus spp. counts in raw material ranged between 4.2-4.7 log10 CFU/g and 3.8-4.1 log10 CFU/g in kapok seeds and between 2.2-2.3 log10 CFU/g and 1.1-1.8 log10 CFU/g in ash lye solution, respectively. Microbial counts in seeds mash during fermentation ranged between 9-10.9 log10 CFU/g for AMB and between 8.6-10.5 log10 CFU/g for Bacillus spp. In dried Mantchoua, AMB counts ranged between 7.7-10.4 log10 CFU/g while Bacillus spp. counts ranged between 7.5-10.3 log10 CFU/g.&#x0D; The fermentation of Mantchoua involved different species of Bacillus spp. At Bobo-Dioulasso pilot plant, B. subtilis subsp. subtilis dominated (50% of the Bacillus isolates) followed by B. cereus sensu lato (28% of the Bacillus isolates) while at Pô traditional production site, B. cereus sensu lato dominated (54% of the Bacillus isolates) followed also by B. subtilis subsp. subtilis (26% of the Bacillus isolates). For the Mantchoua processes including ash lye solution, pH were consistently higher during fermentation (pH 8.6-8.9), and the number of isolated B. cereus sensu lato were lower.

High-Efficiency Conversion of Ionic Liquid-Pretreated Woody Biomass to Ethanol at the Pilot Scale

With a diverse and widely distributed global resource base, woody biomass is a compelling organic feedstock for conversion to renewable liquid fuels. In California, woody biomass comprises the largest fraction of underutilized biomass available for biofuel production, but conversion to fuels is challenged both by recalcitrance to deconstruction and by toxicity toward downstream saccharification and fermentation due to organic acids and phenolic compounds generated during pretreatment. In this study, we optimize pretreatment and scale-up of an integrated one-pot process for deconstruction of California woody biomass using the ionic liquid (IL) cholinium lysinate [Ch][Lys] as a pretreatment solvent. By evaluating the impact of solid loading, solid removal, yeast acclimatization, fermentation temperature, fermentation pH, and nutrient supplementation on final ethanol yields and titers, we achieve nearly full conversion of both glucose and xylose to ethanol with commercial C5-utilizing Saccharomyces cerevisiae. We then demonstrate process scalability in 680 L pilot-scale fermentation, achieving >80% deconstruction efficiency, >90% fermentation efficiency, 27.7 g/L ethanol titer, and >80% ethanol distillation efficiency from the IL-containing hydrolysate post fermentation. This fully integrated process requires no intermediate separations and no intermediate detoxification of the hydrolysate. Using an integrated biorefinery model, current performance results in a minimum ethanol selling price of $8.8/gge. Reducing enzyme loading along with other minor process improvements can reduce the ethanol selling price to $3/gge. This study is the largest scale demonstration of IL pretreatment and biofuel conversion known to date, and the overall biomass-to-ethanol efficiencies are the highest reported to date for any IL-based biomass-to-biofuel conversion.

Effect of purple sweet potato levels (Ipomoea batatas L.) carbohydrate sources on fermentation kinetics and lactic acid production by Lactobacillus paracasei

This research aims to determine the effect of purple sweet potato extract level as a carbohydrate source substrate on the kinetics of fermentation and lactic acid production by Lactobacillus paracasei. Research using L. paracasei, which is a lactic acid bacteria (LAB) collection of the Laboratory of Nutrition Biochemistry of the Faculty of Animal Sciences UGM. Fermentation kinetics were observed with a graph of substrate degradation derived from the Michaelis-Menten equation. Purple sweet potato extract concentration (S) used to determine the value of Km and qmax of L. paracasei was 0,01; 0,05 and 0,1%. Purple sweet potato extract concentration (S), which was used for observing the kinetics fermentation and lactic acid production, was ½ Km, Km and 1,5 Km. Observation of substrate degradation was known by conducting the Antrone test. The results of the fermentation kinetics test in the form of slope values, as a parameter of the speed of substrate degradation L. paracasei. Lactic acid production was measured using the Barker and Summerson methods. Analysis data for the value of Km and qmax observed descriptively. While, the data of the fermentation kinetics test, pH values and production of lactic acid were analyzed using analysis of variance with a Completely Randomized Design (CRD) in a unidirectional pattern. The addition of purple sweet potato extract to liquid fermentation L. paracasei grading 1,5 Km (3 g/100ml) has shown the optimum pH value and lactic acid production but ½ Km concentration shows higher substrate efficiency.

Effect of yellow sweet potato extract (Ipomoea batatas L.) as a prebiotic source for the kinetics of fermentation and the production of lactic acid by Lactobacillus paracasei

This study aims to determine the effect of yellow sweet potato extract as a prebiotic source for fermentation kinetics L. paracasei. Bacteria L. paracasei, which is used here, is a collection of Laboratory Nutritional Biochemistry, Faculty of Animal Science UGM. Concentrations of yellow sweet potato extract used to determine the Km value L. paracasei were 0.01, 0.05, 0.1, and 0.2%. Lactic acid production and fermentation pH value of L. paracasei with different levels of yellow sweet potato extract (2 Km, Km, 1.5 Km) were measured after 24 hours incubation period. Km value bacteria L. paracasei obtained 2.1 g/100ml. Different concentrations of yellow sweet potato (2 Km, Km, 1.5 Km) as a treatment had a significant effect (P<0.05) on the increase in lactic acid produced and decrease in pH. Based on this experiment, it can be seen that level substrate with Km value have not produced optimal lactic acid.

“도초방” 의 제조 공정 개선을 통한 고산도 복숭아 식초 제조

According to the method described in the ancient literature “Imwonsipyukji”, ‘Dochobang’ was mainly composed of lactic acid (756.81 mg/100 mL) and acetic acid (473.66 mg/100 mL) as the main organic acids on the 14th day of fermentation. The acidity of ‘Dochobang’ was 1.09%, resulting in low marketability. Therefore, this study aimed to improve the manufacturing process of peach vinegar and optimize the conditions, including temperature and initial pH, for producing high-acidity vinegar using fermented seeds. We first selected yeasts (Saccharomyces cerevisiae YM27) with excellent alcohol fermentation ability and acetic acid bacteria (Acetobacter oryzifermentans (KACC19301)) with remarkable acid-producing ability and used these in the process-improved two-stage fermentation. The experiment was conducted by 3 treatments of tepmerature(20°C, 30°C and 35°C) and initial pH(3, 4 and 5) for acetic acid fermentation. ‘Dochobang’ fermented alcohol and acetic acid at the same time by natural fermentation. on the other hand, peach wine starter and seed vinegar were added before each fermentation step to increase acetic acid production. Wines fermented at 25°C and 30°C were found to be 9% alcoholic on days sixth and nine days, respectively. Organic acid analysis revealed that the level of acetic acid in vinegar fermented at pH 4 and 20°C increased steadily until day 14 (6,171.3 mg/100 mL). The acidity was 7% on the 21st day of fermentation. Furthermore, as the fermentation progressed, the umami and sourness of the peach vinegar increased. We expect that our findings could improve the quality of peach vinegar recorded in the old literature and can be used in small-scale agricultural companies.

Optimization of cultivation medium and cyclic fed-batch fermentation strategy for enhanced polyhydroxyalkanoate production by Bacillus thuringiensis using a glucose-rich hydrolyzate

The accumulation of petrochemical plastic waste is detrimental to the environment. Polyhydroxyalkanoates (PHAs) are bacterial-derived polymers utilized for the production of bioplastics. PHA-plastics exhibit mechanical and thermal properties similar to conventional plastics. However, high production cost and obtaining high PHA yield and productivity impedes the widespread use of bioplastics. This study demonstrates the concept of cyclic fed-batch fermentation (CFBF) for enhanced PHA productivity by Bacillus thuringiensis using a glucose-rich hydrolyzate as the sole carbon source. The statistically optimized fermentation conditions used to obtain high cell density biomass (OD600 of 2.4175) were: 8.77 g L−1 yeast extract; 66.63% hydrolyzate (v/v); a fermentation pH of 7.18; and an incubation time of 27.22 h. The CFBF comprised three cycles of 29 h, 52 h, and 65 h, respectively. After the third cyclic event, cell biomass of 20.99 g L−1, PHA concentration of 14.28 g L−1, PHA yield of 68.03%, and PHA productivity of 0.219 g L−1 h−1 was achieved. This cyclic strategy yielded an almost threefold increase in biomass concentration and a fourfold increase in PHA concentration compared with batch fermentation. FTIR spectra of the extracted PHAs display prominent peaks at the wavelengths unique to PHAs. A copolymer was elucidated after the first cyclic event, whereas, after cycles CFBF 2–4, a terpolymer was noted. The PHAs obtained after CFBF cycle 3 have a slightly higher thermal stability compared with commercial PHB. The cyclic events decreased the melting temperature and degree of crystallinity of the PHAs. The approach used in this study demonstrates the possibility of coupling fermentation strategies with hydrolyzate derived from lignocellulosic waste as an alternative feedstock to obtain high cell density biomass and enhanced PHA productivity.