Optimization Of Fermentation Conditions Research Articles

Efficient synthesis of limonene production in Yarrowia lipolytica by combinatorial engineering strategies

BackgroundLimonene has a variety of applications in the foods, cosmetics, pharmaceuticals, biomaterials, and biofuels industries. In order to meet the growing demand for sustainable production of limonene at industry scale, it is essential to find an alternative production system to traditional plant extraction. A promising and eco-friendly alternative is the use of microbes as cell factories for the synthesis of limonene.ResultsIn this study, the oleaginous yeast Yarrowia lipolytica has been engineered to produce d- and l-limonene. Four target genes, l- or d-LS (limonene synthase), HMG (HMG-CoA reductase), ERG20 (geranyl diphosphate synthase), and NDPS1 (neryl diphosphate) were expressed individually or fused together to find the optimal combination for higher limonene production. The strain expressing HMGR and the fusion protein ERG20-LS was the best limonene producer and, therefore, selected for further improvement. By increasing the expression of target genes and optimizing initial OD, 29.4 mg/L of l-limonene and 24.8 mg/L of d-limonene were obtained. We also studied whether peroxisomal compartmentalization of the synthesis pathway was beneficial for limonene production. The introduction of d-LS and ERG20 within the peroxisome improved limonene titers over cytosolic expression. Then, the entire MVA pathway was targeted to the peroxisome to improve precursor supply, which increased d-limonene production to 47.8 mg/L. Finally, through the optimization of fermentation conditions, d-limonene production titer reached 69.3 mg/L.ConclusionsIn this work, Y. lipolytica was successfully engineered to produce limonene. Our results showed that higher production of limonene was achieved when the synthesis pathway was targeted to the peroxisome, which indicates that this organelle can favor the bioproduction of terpenes in yeasts. This study opens new avenues for the efficient synthesis of valuable monoterpenes in Y. lipolytica.

Fermentation of Soy-based dairy substitutes by lactic acid bacteria: focus on the process of soy protein hydrolysis

Soy-based dairy substitutes (SBDS) made from soybeans are becoming increasingly popular due to the nutritional benefits of soybeans. The use of lactic acid bacteria (LAB) fermentation to enhance the quality of SBDS is a reasonable strategy, in which protein hydrolysis is one of the key biochemical reaction processes in the fermentation process. However, a systematic analysis is yet to be conducted to comprehensively assess the current impact and potential mechanisms of LAB hydrolyzed soy protein on the quality of SBDS. This review summarizes the effects of LAB hydrolyzed soy proteins on the flavor, texture, nutrient digestion and absorption, bioactive peptide production, and allergenicity of SBDS. In addition, measures to improve the ability of LAB to hydrolyze soy protein were presented, including pretreatment of raw materials, screening of suitable strains, optimization of fermentation conditions, and an outlook on future research directions. From the perspective of protein hydrolysis, this review effectively highlights the significant role of LAB in shaping the quality of SBDS during fermentation. It offers an invaluable reference for those involved in the development of high-caliber SBDS production.

Enhancing the yield of Xenocoumacin 1 in Xenorhabdus nematophila YL001 by optimizing the fermentation process

Xenocoumacin 1 (Xcn 1), antibiotic discovered from secondary metabolites of Xenorhabdus nematophila, had the potential to develop into a new pesticide due to its excellent activity against bacteria, oomycetes and fungi. However, the current low yield of Xcn1 limits its development and utilization. To improve the yield of Xcn1, response surface methodology was used to determine the optimal composition of fermentation medium and one factor at a time approach was utilized to optimize the fermentation process. The optimal medium composed of in g/L: proteose peptone 20.8; maltose 12.74; K2HPO4 3.77. The optimal fermentation conditions were that 25 °C, initial pH 7.0, inoculum size 10%, culture medium 75 mL in a 250 mL shake flask with an agitation rate of 150 rpm for 48 h. Xenorhabdus nematophila YL001 was produced the highest Xcn1 yield (173.99 mg/L) when arginine was added to the broth with 3 mmol/L at the 12th h. Compared with Tryptic Soy Broth medium, the optimized fermentation process resulted in a 243.38% increase in Xcn1 production. The obtained results confirmed that optimizing fermentation technology led to an increase in Xcn1 yield. This work would be helpful for efficient Xcn1 production and lay a foundation for its industrial production.

Metabolic and process engineering of Clostridium tyrobutyricum for efficient hydrogen production from sugarcane molasses

Clostridia is the dominant microorganism in dark-fermentative biohydrogen production, but there have been relatively few studies on hydrogen production by Clostridium tyrobutyricum using cheap biomass. In this study, the important process parameters for hydrogen fermentation, such as substrate concentration, pH and temperature, were optimized systematically. Then, the effect of endogenous hydrogenases overexpression on hydrogen production was studied. To achieve economical hydrogen production from cheap substrate sugarcane molasses, the sucrose metabolic pathway was further introduced into C. tyrobutyricum. As a result, the engineered C. tyrobutyricum produced 1098.4 mL hydrogen with a yield of 248.2 mL/g sugar and productivity of 199.6 mL/L/h under the optimum fermentation conditions, which is the highest hydrogen production (910.37 mmol/L) reported so far using molasses. This study demonstrates that C. tyrobutyricum is a promising cell factory for hydrogen production from cheap and renewable biomass resources.

Optimization of coffee vinegar production from cherry Pulp as by product of arabica coffee processing

Abstract The current high consumption of coffee globally has an impact on the abundance of by-products of coffee processing in the form of cherry pulp which are considered waste and cause environmental problems. The waste from arabica coffee is potential economic value products such as fermented vinegar because of its rich nutrients. The aim of this research was to determine the optimal conditions for acetic acid fermentation and the influence of yeast concentration and nitrogen sources fermented for 60 days. The research was carried out in two stages of fermentation using the Orleans method. Anaerobic alcohol fermentation (20 days) followed by aerobic acetic acid fermentation (40 days). A Randomized Block Factorial Design was used with 2 factors, namely yeast concentration (S15% and S210%) and NPK (N10g, N25g, and N310g), repeated 3 times. Observations on alcoholic fermentation were carried out every 5 days for 20 days regarding ethanol levels. Meanwhile, in acetic acid fermentation, 2.5% vinegar starter was added for each treatment and observations were made every 10 days for 40 days regarding the yield, acetic acid content, pH value and total dissolved solids. The results showed that the highest formation of acetic acid was obtained on day 30 of fermentation. The highest acetic acid content was obtained in the treatment S210%: N25g of 5.27%, pH value of 3.46, TSS value of 0.49 °Bx with a total yield of 42.93%. This is in line with the ethanol content previously formed on day 20 of 11.04% in the same treatment. This value meets the quality standards for fermented vinegar according to SNI 01-4371-1996 by at least 4%.

Microbial Ecology and Fermentation Dynamics of Traditional and Novel Fermented Yogurt in Brazil

Purpose: The aim of the study was to examine microbial ecology and fermentation dynamics of traditional and novel fermented yogurt in Brazil Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study revealed that traditional yogurt production relies on well-established microbial species such as Lactobacillus bulgaricus and Streptococcus thermophilus, which undergo dynamic shifts in population composition throughout fermentation. These shifts are influenced by factors such as temperature, pH, and substrate composition, highlighting the importance of controlling fermentation parameters to optimize product quality and consistency. Novel fermented yogurt products introduce innovative fermentation techniques, starter cultures, and ingredients, resulting in diverse microbial communities and fermentation dynamics. Incorporating prebiotics, specific starter cultures, or probiotics can enhance fermentation efficiency, promote the growth of beneficial microbial species, and improve product texture and flavor. Unique Contribution to Theory, Practice and Policy: Ecological Succession Theory & Metabolic Theory of Ecology may be used to anchor future studies on microbial ecology and fermentation dynamics of traditional and novel fermented yogurt in Brazil. Yogurt producers can optimize fermentation conditions, such as temperature, pH, and fermentation time, to enhance product quality and consistency. Controlling these parameters can promote the growth of desirable microbial species, inhibit the growth of pathogens, and ensure the production of high-quality yogurt. Regulatory agencies should establish guidelines and standards for ensuring the safety of fermented yogurt products. This includes monitoring microbial safety aspects, such as the presence of pathogenic microorganisms and microbial toxins, throughout the production process.

Synergistic Fermentation of Pichia kluyveri and Saccharomyces cerevisiae Integrated with Two-Step Sugar-Supplement for Preparing High-Alcohol Kiwifruit Wine.

Wild yeast suitable for kiwifruit wine fermentation was isolated and purified, and the fermentation process was optimized to increase the alcohol content of the kiwifruit wine. Pichia kluyveri was isolated from kiwifruit pulp by lineation separating, screened by morphological characteristics in Wallerstein Laboratory Nutrient Agar (WL) medium and microscope observation, and further identified by 26S rDNA D1/D2 domain sequence analysis. Taking alcohol content and sensory evaluation as two indexes, the fermentation condition for kiwifruit wine was optimized by single factor and response surface experiment. The optimal fermentation conditions were optimized as follows: the fermentation temperature was at 24 °C, the initial pH was 3.8, the sugar dosage in second step was 8% (w/w), and the inoculating quantity of Pichia kluyveri and Saccharomyces cerevisiae was 0.15 g/L at equal proportion. Under these optimal conditions, the maximum estimated alcohol content was 15.6 vol%, and the kiwifruit wine was light green in color with strong kiwifruit aroma and mellow taste.

Optimization of High-Density Fermentation Conditions for Saccharomycopsis fibuligera Y1402 through Response Surface Analysis.

Saccharomycopsis fibuligera, which produces enzymes like amylase and protease as well as flavor substances like β-phenyl ethanol and phenyl acetate, plays a crucial role in traditional fermented foods. However, this strain still lacks a high-density fermentation culture, which has had an impact on the strain's industrial application process. Therefore, this study investigated the optimization of medium ingredients and fermentation conditions for high-density fermentation of S. fibuligera Y1402 through single-factor design, Plackett-Burman design, steepest ascent test, and response surface analysis. The study found that glucose at 360.61 g/L, peptone at 50 g/L, yeast extract at 14.65 g/L, KH2PO4 at 5.49 g/L, MgSO4 at 0.40 g/L, and CuSO4 at 0.01 g/L were the best medium ingredients for S. fibuligera Y1402. Under these conditions, after three days of fermentation, the total colony count reached 1.79 × 108 CFU/mL. The optimal fermentation conditions were determined to be an initial pH of 6.0, an inoculum size of 1.10%, a liquid volume of 12.5 mL/250 mL, a rotation speed of 120 r/min, a fermentation temperature of 21 °C and a fermentation time of 53.50 h. When fermentation was conducted using the optimized medium and conditions, the total colony count achieved a remarkable value of 5.50 × 109 CFU/mL, exhibiting a substantial increase of nearly 31 times the original value in the optimal culture medium. This significant advancement offers valuable insights and a reference for the industrial-scale production of S. fibuligera.

Preparation and characterization of grouper bone peptides-calcium complex by lactic acid bacteria fermentation

In this study, grouper bone peptides-calcium complex (GPs-Ca) was prepared by lactic acid bacteria fermentation, and its structure and stability were analyzed. Response surface methodology (RSM) optimization was used to determine the optimal fermentation conditions as follows: 4% (v/v) inoculum size, 4.5 g/100 mL glucose addition and fermentation time 75 h,under which the soluble calcium content was 5953.61 mg/L and the peptide content was 21.75 mg/mL. The results of ultraviolet–visible absorption spectroscopy (UV) and fluorescence spectroscopy (Fs) showed a significant spectral shift for GPs-Ca relative to grouper bone peptides (GPs), indicating that peptide combined with calcium to produce a new substance after fermentation. Fourier transform infrared spectroscopy (FTIR) showed that carboxyl groups participated in the formation of GPs-Ca. Scanning electron microscopy (SEM) showed that calcium ions were embedded or adsorbed on the peptide surface. According to the stability analysis, GPs-Ca was stable during heating, alkaline environment and intestinal digestion, but easily dissociated in acidic environment. GPs-Ca prepared by lactic acid bacteria fermentation has the potential to be used as a new type of calcium supplement product, which provides a scientific basis for the high-value utilization of grouper bone.

Transdisciplinary Tactics and Prospects for Medical and Commercial Advancement in Kefir

Background: Kefir, a fermented milk beverage with a rich cultural heritage, has garnered significant attention due to its health benefits and commercial potential. This study explores the convergence of medical science, technology, and market dynamics to position kefir as a functional food with therapeutic applications. Objective: The study aimed to evaluate the health benefits of kefir, optimize its production processes, and investigate its therapeutic potential in chronic diseases and injuries. Methods: A randomized controlled trial was conducted with participants divided into kefir and control groups. Pre- and post-intervention health assessments were performed, measuring cardiovascular health, blood sugar levels, immune response markers, and neurological function. Biochemical analyses of blood samples were conducted to identify changes due to kefir consumption. Statistical analyses were performed using SPSS version 25. For process optimization, Response Surface Methodology (RSM) was applied to optimize fermentation conditions. Experimental studies included in vitro cell culture experiments and in vivo animal models to assess kefir’s effects on diabetes, Alzheimer's disease, and cancer. Microbial analysis was performed using genomic and proteomic techniques, and consumer sensory evaluations were conducted for new kefir formulations. Results: The kefir group showed a significant reduction in mean blood sugar levels from 96.62 mg/dL to 85.18 mg/dL (t-statistic=5.16, p=0.000004), while the control group showed no significant change. Optimized production conditions were determined to be a temperature of 25°C, fermentation time of 24 hours, and a grain-to-milk ratio of 0.1, achieving a quality score of 500. In the diabetes model, the kefir-treated group had a significant reduction in HbA1c levels (6.75) compared to the control group (7.41) (t-statistic=6.14, p=8.12×10^-8). For Alzheimer's disease, amyloid plaque deposition decreased significantly in the kefir group (37.34) versus the control group (50.13) (t-statistic=5.70, p=4.29×10^-7). In the cancer model, tumor growth was significantly reduced in the kefir group (64.18) compared to the control group (98.10) (t-statistic=7.45, p=5.09×10^-10). Microbial counts were highest and most stable under Condition A (11.05×10^7, SD=6.33×10^5). Consumer sensory evaluations of soymilk-based kefir resulted in a mean score of 3.1 (SD=1.32). Conclusion: Kefir demonstrates significant health benefits, including blood sugar regulation, and therapeutic potential in managing diabetes, Alzheimer's disease, and cancer. Optimized production conditions enhance its commercial viability. Future research should focus on long-term effects and real-world applications to validate these findings.

Improvement of nucleotide content of Cordyceps tenuipes by Schisandra chinensis: fermentation process optimization and application prospects.

Nucleotides are important components and the main indicators for judging Cordyceps quality. In this paper, the mixed fermentation process of Schisandra chinensis and Cordyceps tenuipes was systematically studied, and it was proposed that the fermentation products aqueous extract (S-ZAE) had antioxidant activity and anti-AChE ability. Herein, the results of a single factor showed that S. chinensis, yeast extract, inoculum amount, and pH had significant effects on nucleotide synthesis. The fermentation process optimization results were 3% glucose, 0.25% KH2PO4, 2.1% yeast extract, and S. chinensis 0.49% (m/v), the optimal fermentation conditions were 25℃, inoculum 5.8% (v/v), pH 3.8, 6 d. The yield of total nucleotides in the scale-up culture was 0.64 ± 0.027mg/mL, which was 10.6 times higher than before optimization. S-ZAE has good antioxidant and anti-AChE activities (IC50 0.50 ± 0.050mg/mL). This fermentation method has the advantage of industrialization, and its fermentation products have the potential to become good functional foods or natural therapeutic agents.

Functional Characterization of F3H Gene and Optimization of Dihydrokaempferol Biosynthesis in Saccharomyces cerevisiae.

The 1092 bp F3H gene from Trapa bispinosa Roxb., which was named TbF3H, was cloned and it encodes 363 amino acids. Bioinformatic and phylogenetic tree analyses revealed the high homology of TbF3H with flavanone 3-hydroxylase from other plants. A functional analysis showed that TbF3H of Trapa bispinosa Roxb. encoded a functional flavanone 3-hydroxylase; it catalyzed the formation of dihydrokaempferol (DHK) from naringenin in S. cerevisiae. The promoter strengths were compared by fluorescence microscopy and flow cytometry detection of the fluorescence intensity of the reporter genes initiated by each constitutive promoter (FITC), and DHK production reached 216.7 mg/L by the promoter adjustment strategy and the optimization of fermentation conditions. The results presented in this study will contribute to elucidating DHK biosynthesis in Trapa bispinosa Roxb.

Co-fermentation and post-processing: development of a novel myrtle rice beverage, and analysis of its product characteristics

ABSTRACT To fully develop the medicinal and edible value of myrtle and improve the market visibility, myrtle berries and glutinous rice were used as raw materials and co-fermented using rice leaven. Uniform design method was used to determine the optimal fermentation conditions. The co-fermentation product was then underwent post-processing, including blending, grinding and homogenization, to produce a novel myrtle rice beverage, which was analyzed for product characteristics. Results showed that the optimal fermentation conditions were a myrtle berries of 24%, a rice leaven of 1%, a water addition amount of 100%, a fermentation temperature of 22°C, a fermentation time of 96 h. The co-fermented product was diluted 1:3 with water, ground, and homogenized with 0.1% agar and 0.2% xanthan gum to produce the final myrtle rice beverage. The beverage boasts a low sugar and alcohol content, along with a moderate level of acidity, making it a healthy beverage with antioxidant properties.

Optimization of fermentation conditions for the production of γ-aminobutyric acid by Lactobacillus hilgardii GZ2 from traditional Chinese fermented beverage system.

γ-Aminobutyric acid (GABA) is a crucial neurotransmitter with wide application prospects. In this study, we focused on a GABA-producing strain from a traditional Chinese fermented beverage system. Among the six isolates, Lactobacillus hilgardii GZ2 exhibited the greatest ability to produce GABA in the traditional Chinese fermented beverage system. To increase GABA production, we optimized carbon sources, nitrogen sources, temperature, pH, and monosodium glutamate and glucose concentrations and conducted fed-batch fermentation. The best carbon and nitrogen sources for GABA production and cell growth were glucose, yeast extract and tryptone. Gradual increases in GABA were observed as the glucose and monosodium glutamate concentrations increased from 10g/L to 50g/L. During fed-batch fermentation, lactic acid was used to maintain the pH at 5.56, and after feeding with 0.03g/mL glucose and 0.4g/mL sodium glutamate for 72h, the GABA yield reached 239g/L. This novel high-GABA-producing strain holds great potential for the industrial production of GABA, as well as the development of health-promoting functional foods and medical fields.

Optimization of fermentation process and characterization of non-alcoholic functional beverage from pigmented rice varieties

Traditional foods have recently gained importance because of their role in the United Nations’ sustainable development goals (SDG), ensuring health benefits and economic development. Fermented rice water (FRW) is a popular traditional drink among low socio-economic groups, especially in Southeast Asia. This study focused on optimizing fermentation conditions for sustainable food production and consumption of FRW using pigmented rice, followed by analyzing the nutritional, physicochemical and phytochemical properties. Fermenting cooked rice in water for 16 h at 37 °C produced bubbles, mild sourness and zero alcohol content. Flavors and sugar were added to optimized FRW as food additives to enhance palatability. Nutritional profiling showed that black flavored fermented rice water (FFRW) had the highest protein (0.06%), carbohydrate (13.25 g/100 mL) and calorific value (78.09 kcal/100 mL). However, brown FFRW had the highest vitamin B3 (3.12 mg/L) and mineral content. Phenolic and antioxidant activity was highest in black FFRW, followed by red and brown, with maximum bio-accessibility of polyphenols found in black FFRW (75.25%). All FFRW were microbiologically safe and stable during a storage period of 30 days at 4 °C. All FRW had >8 log CFU count, with black FFRW having the highest LAB count, indicating their possible probiotic potential in addressing malnutrition and undernourishment. Thus, FFRW holds the potential to be commercialized in the food and beverage sector due to its rich nutritional and functional properties. Furthermore, the consumption of FFRW will preserve traditional knowledge, ensure sustainable livelihoods and contribute to achieving development goals.

Promising Application, Efficient Production, and Genetic Basis of Mannosylerythritol Lipids.

Mannosylerythritol lipids (MELs) are a class of glycolipids that have been receiving increasing attention in recent years due to their diverse biological activities. MELs are produced by certain fungi and display a range of bioactivities, making them attractive candidates for various applications in medicine, agriculture, and biotechnology. Despite their remarkable qualities, industrial-scale production of MELs remains a challenge for fungal strains. Excellent fungal strains and fermentation processes are essential for the efficient production of MELs, so efforts have been made to improve the fermentation yield by screening high-yielding strains, optimizing fermentation conditions, and improving product purification processes. The availability of the genome sequence is pivotal for elucidating the genetic basis of fungal MEL biosynthesis. This review aims to shed light on the applications of MELs and provide insights into the genetic basis for efficient MEL production. Additionally, this review offers new perspectives on optimizing MEL production, contributing to the advancement of sustainable biosurfactant technologies.

High production of ectoine from methane in genetically engineered Methylomicrobium alcaliphilum 20Z by preventing ectoine degradation

BackgroundMethane is a greenhouse gas with a significant potential to contribute to global warming. The biological conversion of methane to ectoine using methanotrophs represents an environmentally and economically beneficial technology, combining the reduction of methane that would otherwise be combusted and released into the atmosphere with the production of value-added products.ResultsIn this study, high ectoine production was achieved using genetically engineered Methylomicrobium alcaliphilum 20Z, a methanotrophic ectoine-producing bacterium, by knocking out doeA, which encodes a putative ectoine hydrolase, resulting in complete inhibition of ectoine degradation. Ectoine was confirmed to be degraded by doeA to N-α-acetyl-L-2,4-diaminobutyrate under nitrogen depletion conditions. Optimal copper and nitrogen concentrations enhanced biomass and ectoine production, respectively. Under optimal fed-batch fermentation conditions, ectoine production proportionate with biomass production was achieved, resulting in 1.0 g/L of ectoine with 16 g/L of biomass. Upon applying a hyperosmotic shock after high–cell–density culture, 1.5 g/L of ectoine was obtained without further cell growth from methane.ConclusionsThis study suggests the optimization of a method for the high production of ectoine from methane by preventing ectoine degradation. To our knowledge, the final titer of ectoine obtained by M. alcaliphilum 20ZDP3 was the highest in the ectoine production from methane to date. This is the first study to propose ectoine production from methane applying high cell density culture by preventing ectoine degradation.

Combinatorial metabolic engineering of Escherichia coli for de novo production of structurally defined and homogeneous Amino oligosaccharides

Amino oligosaccharides (AOs) possess various biological activities and are valuable in the pharmaceutical, food industries, and agriculture. However, the industrial manufacturing of AOs has not been realized yet, despite reports on physical, chemical, and biological approaches. In this study, the de novo production of chitin oligosaccharides (CHOS), a type of structurally defined AOs, was achieved in Escherichia coli through combinatorial pathway engineering. The most suitable glycosyltransferase for CHOS production was found to be NodCL from Mesorhizobium Loti. Then, by knocking out the nagB gene to block the flow of N-acetyl-d-glucosamine (NAG) to the glycolytic pathway in E. coli and adjusting the copy number of NodCL-coding gene, the CHOS yield was increased by 6.56 times. Subsequently, by introducing of UDP-N-acetylglucosamine (UDP-GlcNAc) salvage pathway for and optimizing fermentation conditions, the yield of CHOS reached 207.1 and 468.6 mg/L in shake-flask cultivation and a 5-L fed-batch bioreactor, respectively. Meanwhile, the concentration of UDP-GlcNAc was 91.0 mg/L, the highest level reported in E. coli so far. This study demonstrated, for the first time, the production of CHOS with distinct structures in plasmid-free E. coli, laying the groundwork for the biosynthesis of CHOS and providing a starting point for further engineering and commercial production.

Bacillus velezensis strain NA16 shows high poultry feather-degrading efficiency, protease and amino acid production

Isolated Bacillus velezensis strain NA16, which produces proteases, amino acids and the transcription levels of different keratinolytic enzymes and disulfide reductase genes in whole gene sequencing, was evaluated during feather degradation. The result shows under optimum fermentation conditions, chicken feather fermentation showed total amino acid concentration of 7599 mg/L, degradation efficiency of 99.3% at 72 h, and protease activity of 1058 U/mL and keratinase activity of 288 U/mL at 48 h. Goose feather fermentation showed total amino acid concentration of 4918 mg/L (96 h), and degradation efficiency was 98.9% at 120 h. Chicken feather fermentation broth at 72 h showed high levels of 17 amino acids, particularly phenylalanine (1050 ± 1.90 mg/L), valine (960 ± 1.04 mg/L), and glutamic (950 ± 3.00 mg/L). Scanning electron microscopy and Fourier transform infrared analysis revealed the essential role of peptide bond cleavage in structural changes and degradation of feathers. Protein purification and zymographic analyses revealed a key role in feather degradation of the 39-kDa protein encoded by gene1031, identified as an S8 family serine peptidase. Whole genome sequencing of NA16 revealed 26 metalloproteinase genes and 22 serine protease genes. Among the proteins, S8 family serine peptidase (gene1031, gene1428) and S9 family peptidase (gene3132) were shown by transcription analysis to play major roles in chicken feather degradation. These findings revealed the transcription levels of different families of keratinolytic enzymes in the degradation of feather keratin by microorganisms, and suggested potential applications of NA16 in feather waste management and amino acid production.

Effects of Fermentation Temperature and Time on Chickpea-Initiated Sourdough Production

Chickpea is a nutritious staple pulse with numerous consumption patterns. It is also used in bakery products, especially in bread, in chickpea flour, fermented-chickpea liquor (FCL), and chickpea yeast (FCL-fermented sourdough) in various countries. However, a large variation exists in the traditional fermentation of FCL and chickpea yeast (CY). In this study, fermentation parameters (cracked-chickpea size, water-chickpea ratio, fermentation temperature, and fermentation time) for the production of FCL and CY were sequentially optimized through separate RSM designs. Therefore, this study aimed to optimise the fermentation conditions for preparing both FCL and CY. First, FCL production parameters of fermentation temperature, time, chickpea particle size, and water-chickpea ratio were optimized and determined to be 40°C, 26 h, 2-6 mm, and 4:1 ratio, respectively. Secondly, the CY process parameters (fermentation temperature and time) were optimized using the optimized FCL conditions and determined to be 38°C and 9 h. The validation studies proved no statistical difference (p>0.05) between the RSM-model predicted and experimental responses. At the optimized fermentation conditions, the FCL and CY had pH values of 4.44 and 4.31 and LAB counts of 9.87 and 9.08 log cfu/g. The optimum fermentation conditions determined in this study are somewhat comparable to those commonly employed in the traditional preparations of both FCL and CY. Such optimization could lead to the better utilization of FCL and CY in the food industry and improved consumer health outcomes.