Optimization of Medium Composition for Biomass Production of Lactobacillus plantarum 200655 Using Response Surface Methodology

Optimization of fermentation conditions for enhanced acetylcholine and biomass production of Lactiplantibacillus plantarum AM2 using the Taguchi approach

This study aimed to optimize the fermentation conditions and medium composition for maximum acetylcholine (ACh) and biomass production by Lactiplantibacillus plantarum AM2 using the Taguchi array design, which enables efficient identification of influential variables through minimal experimental runs. Seven key factors were evaluated: beef extract, peptone, yeast extract, glucose, pH, agitation rate, and inoculation size. The optimization process identified the most significant variables influencing ACh and biomass production, with beef extract and peptone being critical for ACh synthesis, while inoculation size was a critical determinant of biomass yield. The optimal conditions for ACh production were determined as beef extract (11 g/l), peptone (40 g/l), yeast extract (5 g/l), glucose (20 g/l), pH 5.7, no agitation, and 1% (v/v) inoculation size, resulting in a predicted ACh concentration of 490.83 pg/ml and an experimental value of 495.8 pg/ml. For biomass production, the optimal conditions were beef extract (8 g/l), peptone (10 g/l), yeast extract (20 g/l), glucose (35 g/l), pH 6.6, agitation at 150 rpm, and 4% (v/v) inoculation size, yielding a predicted biomass of 20.58 g/l and an experimental value of 21.3 g/l. The optimized conditions significantly improved ACh production (6.32-fold) and biomass production (4.56-fold) compared to basal conditions. These findings highlight the efficiency of the Taguchi approach in enhancing the production of ACh and biomass, providing insights into the functional niche of Lactiplantibacillus plantarum AM2 for potential industrial applications and its use in a symbiotic form.

Study on Lacticaseibacillus casei TCS fermentation kinetic models and high-density culture strategy

This study enhanced the production efficiency of Lacticaseibacillus casei TCS by optimizing medium composition and fermentation conditions for high-density culture. Initially, single-factor and orthogonal experimental designs and the response surface methodology were used to determine the optimal concentrations of medium. Subsequently, we applied the artificial neural network-genetic algorithm optimization method, which significantly increased the viable bacterial count. Fermentation kinetics were modeled using logistic growth and Luedeking-Piret models, which accurately predicted cell growth. Amberlite IRA 67, an anion exchange resin, effectively adsorbed lactic acid and maintained pH levels. Furthermore, the combined use of fed-batch fermentation and ion exchange alleviated the effects of acid inhibition, salt stress, and substrate limitation, resulting in a maximum cell density of 10.01 lg CFU/mL, a 9.3-fold increase over the basal medium. This study develops a robust and cost-effective strategy for the industrial production of L. casei TCS, significantly optimizing probiotic production processes. IMPORTANCE Lacticaseibacillus casei TCS possesses outstanding aromatic characteristics, making it suitable for producing fermented dairy products. The goal of cultivating Lacticaseibacillus casei TCS at high density is to increase production yields, overcome challenges related to acid inhibition, and optimize fermentation processes. This study employed an artificial neural network (ANN) and genetic algorithms (GA) to determine the ideal composition of the proliferation medium for Lactobacillus casei TCS. It constructed a dynamic model to track bacterial growth, product formation, and substrate consumption during fermentation, analyzing the process's dynamic patterns. Furthermore, by utilizing resin adsorption and fed-batch cultivation techniques, the production of lactic acid as a by-product was effectively minimized. This approach enabled Lactobacillus casei to multiply rapidly to high concentrations, laying a foundation for the industrial production of high-yield aroma starters. This advancement supports the bacterium's application in various sectors, including dairy processing and functional food production.

Industrial production and functional profiling of probiotic Pediococcus acidilactici 72 N for potential use as a swine feed additive

This study aimed to achieve industrial-scale production of the Thai native swine-derived probiotic strain Pediococcus acidilactici 72 N (P72N) using a cost-effective, food-grade modified medium, and to assess the efficacy of this medium by evaluating the probiotic's functional characteristics and metabolomic profile. Conventional and statistical optimization techniques were used to screen food-grade carbon sources (glucose, dextrose, sucrose) and nitrogen sources (beef extract, yeast extract, sweet whey) to develop the optimal formulation. The final medium contained 10 g/L dextrose, 45 g/L yeast extract, 5 g/L sodium acetate, 2 g/L ammonium citrate, 2 g/L di-potassium hydrogen phosphate, 1 g/L Tween 80, 0.1 g/L magnesium sulfate, and 0.05 g/L manganese sulfate. This formulation achieved significantly higher viable cell counts compared to commercial MRS medium. Scale-up fermentation in 5 L and 50 L fermenters under controlled conditions (37 °C, pH 6.5, 120 rpm) yielded viable cell counts exceeding 9.60 log CFU/mL within 12 h, reducing production costs by 67-86%. P72N in the modified medium demonstrated improved tolerance to environmental stresses. Metabolomic analysis revealed that P72N produced a variety of bioactive metabolites, particularly 1,4-dihydroxy-2-naphthoic acid (1,4-DHNA) and indolelactic acid (ILA) which were detected in higher levels in the modified medium, demonstrating its suitability for industrial production of P72N as a potential feed additive for swine farming.

High-Density Fermentation of Lactobacillus plantarum P6: Enhancing Cell Viability via Sodium Alginate Enrichment

Lactobacillus plantarum exhibits a wide range of beneficial physiological functions, including maintaining intestinal microbiota balance, reducing serum cholesterol, and promoting digestive health. According to the specific nutrient requirements of Lactobacillus plantarum P6, we investigated the effects of various carbon sources, nitrogen sources, trace elements, growth-promoting substances, as well as the initial pH and inoculum size on the growth of Lactobacillus plantarum P6 under fermentation conditions. The optimal growth conditions for Lactobacillus plantarum P6 were identified to facilitate high-density fermentation in small-scale fermenter production, achieving a cell concentration of 1.03 × 1011 CFU/mL. This resulted in a 2.5-fold increase in bacterial wet weight, and fermentation time was reduced to 12 h when utilizing a specific medium enriched with 0.2% sodium alginate. It is hypothesized that sodium alginate forms a protective film around the bacterial cells, promoting cell aggregation and enhancing self-coalescence, potentially triggering a bacterial community effect. These results provide a basis for the industrial-scale high-density cultivation of Lactobacillus plantarum, offering potential for enhanced biotechnological applications.

Enhancement of Bioactive Compounds and Survival of Lactobacillus acidophilus Grown in the Omega-6, -7 Riched Cyanobacteria Spirulina platensis

Lactobacillus acidophilus is a probiotic commonly used in aquaculture to enhance the growth and immune system of aquatic species through the synthesis of various enzymes, and antimicrobial compounds like lactic acid. Traditional method of growing L. acidophilus involes using the De Man-Rogosa-Sharpe (MRS) medium. However, L. acidophilus belongs to a non-spore forming group, which make it vulnerable to stress conditions, especially during the usage process. Therefore, the present study aimed to improve the survival rate, antibacterial activity, and enrich the polyunsaturated fatty acids (PUFAs) content of L. acidophilus LB when cultured in an algae-supplemented medium, thus increasing its benefits in aquaculture applications. Using different algae biomass species as an alternative to MRS medium for the growth of L. acidophilus LB, the results showed that Spirulina platensis promoted the highest density of L. acidophilus LB. When grown in (S. platensis + glucose) medium, L. acidophilus LB produced the highest lactic acid concentration of 18.24 ± 2.43 mg/mL and survived in extreme conditions such as 4% NaCl, pH 1.0-2.0, and 50 ºC, and inhibited 99.82 ± 0.24% of Vibrio parahaemolyticus population after 2 days of treatment. Additionally, it was observed that the PUFAs content, specifically omega-6, and -7, also increased in the fermentation mixture as compared to the control sample. These findings highlighted the potential of utilizing the cyanobacteria S. platensis as an alternative, eco-friendly growth substance for L. acidophilus LB to enhance its bioactivity and viability under extreme conditions.

A novel Lactiplantibacillus plantarum strain: probiotic properties and optimization of the growth conditions by response surface methodology

The objective of this study is to explore the probiotic properties and optimal growth conditions of Lactiplantibacillus plantarum BG24. L. plantarum BG24 exhibited a remarkable ability to utilize lactose, and to grow under acidic conditions and in the presence of high levels of bile salts. The strain showed the highest antibacterial activity against L. monocytogenes Scott A (zone of inhibition: 26 mm). L. plantarum BG24 was found to be resistant to 8 of the tested 19 antibiotics using the disc diffusion method.and its multiple antibiotic resistance (MAR) index was calculated as 0.421. The adhesion rate to human intestinal epithelial Caco-2 cells was determined as 37.51%. The enzyme profile of L. plantarum BG24 was investigated using API ZYM test kit and the highest enzymatic activities were found for Leucine arylamidase, β-glucosidase, Valine arylamidase, β-galactosidase and N-acetyl-β-glucosaminidase. L. plantarum BG24 strain showed higher microbial growth under static conditions (6.60 OD600) compared to 100 rpm (5.73 OD600) and 200 rpm (5.02 OD600) shaking speed due to its facultative anaerobic characteristic. However, different inoculation rates and glucose addition did not make a statistically significant difference on biomass formation (p > 0.05). The specific growth rate of L. plantarum BG24 was 0.416 h-1, the doubling time was 1.67 h, and the biomass productivity value was 0.14 gL-1 h-1 in the original MRS broth (pH 5.7) while higher values were found as 0.483 h-1, 1.43 h and 0.17 gL-1 h-1, respectively, in MRS broth (pH 6.5) medium enriched with 5 g/L yeast extract. The stirred tank bioreactor was used to optimise the growth of BG24 strain. The process variables was optimized at 0.05 vvm of aeration rate, 479 rpm of agitation speed, 3% of inoculation rate and 18 h of incubation time. The maximum biomass (g/L) production was obtained as 3.84 g/L at the optimized conditions.

The Metabolomics Changes in Luria-Bertani Broth Medium under Different Sterilization Methods and Their Effects on Bacillus Growth

Luria-Bertani broth (LB) culture medium is a commonly used bacterial culture medium in the laboratory. The nutrient composition, concentration, and culture conditions of LB medium can influence the growth of microbial strains. The purpose of this article is to demonstrate the impact of LB liquid culture medium on microbial growth under different sterilization conditions. In this study, LB medium with four different treatments was used, as follows: A, LB medium without treatments; B, LB medium with filtration; C, LB medium with autoclaving; and D, LB medium with autoclaving and cultured for 12 h. Subsequently, the protein levels and antioxidant capacity of the medium with different treatments were measured, and the effects of the different LB medium treatments on the growth of microorganisms and metabolites were determined via 16s rRNA gene sequencing and metabolomics analysis, respectively. Firmicutes and Lactobacillus were the dominant microorganisms, which were enriched in fermentation and chemoheterotrophy. The protein levels and antioxidant capacity of the LB medium with different treatments were different, and with the increasing concentration of medium, the protein levels were gradually increased, while the antioxidant capacity was decreased firstly and then increased. The growth trend of Bacillus subtilis, Bacillus paralicheniformis, Micrococcus luteus, and Alternaria alternata in the medium with different treatments was similar. Additionally, 220 and 114 differential metabolites were found between B and C medium, and between C and D medium, which were significantly enriched in the "Hedgehog signaling pathway", "biosynthesis of plant secondary metabolites", "ABC transporters", "arginine and proline metabolism", and "linoleic acid metabolism". LB medium may be a good energy source for Lactobacillus growth with unsterilized medium, and LB medium filtered with a 0.22 μm filter membrane may be used for bacterial culture better than culture medium after high-pressure sterilization. LB medium still has the ability for antioxidation and to keep bacteria growth whether or not autoclaved, indicating that there are some substances that can resist a high temperature and pressure and still maintain their functions.

Alternative culture medium design for biomass production of autochthonous meat starter Latilactobacillus sakei sp. sakei ACU-2

The autochthonous strain Latilactobacillus sakei sp. sakei ACU-2 was selected as a meat starter culture for dry sausage production. Transferring this strain from laboratory scale to industry requires an increase in biomass production, while lowering process costs. In this study, a combination of techniques was applied in order to optimize the culture medium composition to enhance biomass production of L. sakei ACU-2. One variable at a time experiments, Plackett-Burman design, and mixture design were performed to fulfill the strain nutritional requirements. Eventually, the optimized formulation contained 19.46 g/L yeast extract; 8.28 g/L whey protein concentrate; 2.26 g/L soy peptone; 30 g/L cerelose; 1 g/L Tween 80; 5 g/L sodium acetate; 0.2 g/L magnesium sulfate and 0.05 g/L manganese sulfate. When L. sakei ACU-2 was cultivated in a bioreactor using the alternative medium, an enhancement of 75.5% of biomass production was achieved, in comparison to its growth in the commercial de Man, Rogosa, and Sharpe medium. Furthermore, a reduction of 62-86% of the cost was also attained. These results support a promising large-scale application of the designed medium for high biomass yields of the starter culture at minor costs.

Optimization of Probiotic Lactobacilli Production for In-Feed Supplementation to Feedlot Cattle

The selection of probiotic bacteria based on their beneficial characteristics does not necessarily mean they can be later scaled up and used for technological applications and formula design. Three probiotic strains—Lactobacillus acidophilus CRL2074, Limosilactobacillus fermentum CRL2085, and Limosolactobacillus mucosae CRL2069, originally isolated from feedlot cattle feces—have demonstrated beneficial characteristics when used as in-feed probiotics. Therefore, the current study was conducted to develop a low-cost culture medium to optimize growth conditions to enhance biomass production. The study also sought to identify appropriate cryoprotective agents to sustain high functional cell numbers after freeze drying. A central composite design was applied to determine the optimal medium composition. This yielded a simplified, low-cost effective medium containing 3% molasses and industrial yeast extracts (0.5 to 2.5%) as carbon and nitrogen sources, which were added to a basal medium for each strain. Established production conditions at 37 °C, without agitation, and pH-controlled for the CRL2085 and CRL2069 strains, and free pH for the CRL2074 strain, allowed us to obtain biomass yields of 12.95, 18.20, and 12.25 g, respectively, at 24-h incubation, compared with the MRS medium. In addition, the cryoprotective effect of the selected agents was demonstrated to be strain-dependent. Thus, the highest viability (109–1010 CFU/g), stability during 30-d storage, and survival rate (88–99%) were achieved when 10% MSG (monosodium glutamate), sucrose + fructose + trehalose + WPC (whey protein concentrate) + 10% MSG, and 1.2% WPC + 10% trehalose, were used for freeze drying CRL2074, CRL2085, and CRL2069, respectively. Moreover, the probiotic strains retained their probiotic functionality when hydrophobic characteristics were evaluated. These results highlight the need to perform strain-specific evaluation of the critical factors involved in the large-scale production of probiotic lactobacilli to sustain viability and stability after the freeze drying and storage processes.

Molecular Detection and Identification of Plant-Associated Lactiplantibacillus plantarum

Lactiplantibacillus plantarum is a lactic acid bacterium often isolated from a wide variety of niches. Its ubiquity can be explained by a large, flexible genome that helps it adapt to different habitats. The consequence of this is great strain diversity, which may make their identification difficult. Accordingly, this review provides an overview of molecular techniques, both culture-dependent, and culture-independent, currently used to detect and identify L. plantarum. Some of the techniques described can also be applied to the analysis of other lactic acid bacteria.

Machine learning-assisted medium optimization revealed the discriminated strategies for improved production of the foreign and native metabolites

The composition of medium components is crucial for achieving the best performance of synthetic construction in genetically engineered cells. Which and how medium components determine the performance, e.g., productivity, remain poorly investigated. To address the questions, a comparative survey with two genetically engineered Escherichia coli strains was performed. As a case study, the strains carried the synthetic pathways for producing the aromatic compounds of 4-aminophenylalanine (4APhe) or tyrosine (Tyr), common in the upstream but differentiated in the downstream metabolism. Bacterial growth and compound production were examined in hundreds of medium combinations that comprised 48 pure chemicals. The resultant data sets linking the medium composition to bacterial growth and production were subjected to machine learning for improved production. Intriguingly, the primary medium components determining the production of 4PheA and Tyr were differentiated, which were the initial resource (glucose) of the synthetic pathway and the inducer (IPTG) of the synthetic construction, respectively. Fine-tuning of the primary component significantly increased the yields of 4APhe and Tyr, indicating that a single component could be crucial for the performance of synthetic construction. Transcriptome analysis observed the local and global changes in gene expression for improved production of 4APhe and Tyr, respectively, revealing divergent metabolic strategies for producing the foreign and native metabolites. The study demonstrated that ML-assisted medium optimization could provide a novel point of view on how to make the synthetic construction meet the designed working principle and achieve the expected biological function.

Probiotics media: significance, challenges, and future perspective - a mini review

The health benefits associated with probiotics have increased their application in pharmaceutical formulations and functional food development. High production of probiotic biomass requires a cost-effective production method and nutrient media optimization. The biomass production of probiotics can be enhanced by optimizing growth parameters such as substrate, pH, incubation time, etc. For economical industrial production of probiotic biomass, it is required to design a new medium with low cost. Wastes from the food industries are promising components for the development of the low-cost medium. Industrial wastes such as cheese whey and corn steep liquor are excellent examples of reliable sources of nitrogen for the biomass production of probiotic bacteria. The increased yield of biomass reduced the cost of production. This review focuses on the importance of probiotic media for biomass production and its challenges.

Graphical Abstract

Optimization of an Industrial Medium and Culture Conditions for Probiotic Weissella cibaria JW15 Biomass Using the Plackett-Burman Design and Response Surface Methodology

The objective of this study was to optimize industrial-grade media for improving the biomass production of Weissella cibaria JW15 (JW15) using a statistical approach. Eleven variables comprising three carbon sources (glucose, fructose, and sucrose), three nitrogen sources (protease peptone, yeast extract, and soy peptone), and five mineral sources (K₂HPO₄, potassium citrate, L-cysteine phosphate, MgSO₄, and MnSO₄) were screened by using the Plackett-Burman design. Consequently, glucose, sucrose, and soy peptone were used as significant variables in response surface methodology (RSM). The composition of the optimal medium (OM) was 22.35 g/l glucose, 15.57 g/l sucrose, and 10.05 g/l soy peptone, 2.0 g/l K₂HPO₄, 5.0 g/l sodium acetate, 0.1 g/l MgSO₄·7H₂O, 0.05 g/l MnSO₄·H₂O, and 1.0 g/l Tween 80. The OM significantly improved the biomass production of JW15 over an established commercial medium (MRS). After fermenting OM, the dry cell weight of JW15 was 4.89 g/l, which was comparable to the predicted value (4.77 g/l), and 1.67 times higher than that of the MRS medium (3.02 g/l). Correspondingly, JW15 showed a rapid and increased production of lactic and acetic acid in the OM. To perform a scale-up validation, batch fermentation was executed in a 5-l bioreactor at 37°C with or without a pH control at 6.0 ± 0.1. The biomass production of JW15 significantly improved (1.98 times higher) under the pH control, and the cost of OM was reduced by two-thirds compared to that in the MRS medium. In conclusion, OM may be utilized for mass producing JW15 for industrial use.

Synergistic antimicrobial activity of ε-polylysine, chestnut extract, and cinnamon extract against Staphylococcus aureus

A mixed natural preservative composed of ε-polylysine (ε-PL), chestnut 70% ethanol extract (NE), and cinnamon hydrothermal extract (CW), was investigated for the reduction of Staphylococcus aureus. The minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of seven natural extracts were investigated against a cocktail of three strains of S. aureus (ATCC 25923, ATCC 33591, and ATCC 33594). Three important factors (ε-PL, NE, and CW) were selected by using the Plackett-Burman (PB) design for the response surface model (P < 0.001). Following a central composite design, S. aureus were treated with mixtures of natural preservatives that included ε-PL, NE, and CW. The MIC and MBC of ε-PL and the natural extracts and ranged from 1 to 16 mg/mL (R² = 0.9857). The mixed natural preservative presented a synergistic antibacterial effect, at the optimum point. These results suggest that mixed natural preservatives of ε-PL, NE, and CW can lower the economic cost of food processing.

Microbial Population Succession and Community Diversity and Its Correlation with Fermentation Quality in Soybean Meal Treated with Enterococcus faecalis during Fermentation and Aerobic Exposure

This study assessed the effects of Enterococcus faecalis (E. faecalis) in combination with protease on fermentation characteristics and microbial communities during ensiling and aerobic exposure phases of soybean meal (SBM). In this study, response surface methodology (RSM) was used to optimize the optimal growth conditions of E. faecalis ZZUPF95, which produced protease, and fermented SBM under the optimal fermentation conditions. The fermentation test was divided into four groups as follows: CK (Control check), ZZUPF95, Protease and ZZUPF95+Protease groups. Results showed that the best medium ratio of ZZUPF95 was glucose 1%, peptone 2%, inorganic salt 1.47%; fermentation time 36 h, inoculation amount 10%, ratio of material to water 1:1 is the optimal fermentation scheme; after fermentation and aerobic exposure treatment, ZZUPF95 and ZZUPF95 + Protease group can reduce the pH of feed, improve the content of lactic acid in the fermentation system, and have the effect of inhibiting the reproduction of pathogenic bacteria, increasing the content of crude protein and ether extract, and degrading crude fiber; the microbial community of SBM were changed after fermentation and aerobic exposure. This study explored the changes of fermentation quality of SBM, which has certain theoretical value to improve the fermentation mode and storage of SBM.