The optimization of l-lactic acid production from sweet sorghum juice by mixed fermentation of Bacillus coagulans and Lactobacillus rhamnosus under unsterile conditions

Evaluation of Different Nutritional Sources in Lactic Acid Bacteria Fermentation for Sustainable Postbiotic Production

In recent years, interest in postbiotics has grown due to their potential health benefits and applications in food systems. This study evaluated various nutritional sources for lactic acid bacteria (LAB) fermentation to enhance postbiotic production. Three LAB strains were tested: Pediococcus acidilactici CECT 9879 (PA), Weissella cibaria CECT 30731 (WC), and Lactococcus lactis CECT 30734 (LL). Fermentation experiments assessed bacterial growth, pH levels, and antibacterial activity against E. coli using different carbon and nitrogen sources. Fructose and xylose significantly improved growth in WC (9.39 ± 0.16 log CFU/mL) and LL (9.37 ± 0.22 log CFU/mL) compared to glucose. Ribose enhanced antimicrobial activity in PA (41.67 ± 2.89%) and WC (50.00 ± 0.00%) relative to glucose. Additionally, plant-based nitrogen sources, such as soy (LL: 8.93 ± 0.12 log CFU/mL and 81.67 ± 2.89%) and wheat (WC: 9.40 ± 0.17 log CFU/mL and 65.00 ± 0.00%), along with microbial sources like yeast (PA: 9.57 ± 0.12 log CFU/mL and 40.00 ± 0.00%), effectively supported growth and antibacterial activity. These findings highlight the potential of developing animal-free fermentation media that meet nutritional, safety, and sustainability criteria while making a significant contribution to the optimization of postbiotic production.

Enhanced production of lactic acid from pretreated rice straw using co-cultivation of Bacillus licheniformis and Bacillus sonorenesis

Lactic acid (LA) production from sugar mixture derived from lignocellulosic rice straw employing co- culture system of thermotolerant and inhibitor tolerant Bacillus licheniformis DGB and Bacillus sonorenesis DGS15 was carried out. In minimal media, both the strains of Bacillus DGB and DGS15 worked together by efficiently utilising glucose and xylose respectively. Response Surface Methodology (RSM) was used for optimisation of pretreatment of rice straw to achieve maximum yield of 50.852 g/L total reducing sugar (TRS) from 100 gm of rice straw biomass. Pretreatment of rice straw resulted in its delignification, as confirmed by FTIR spectroscopy, since the peak at 1668 cm-1 disappeared due to removal of lignin and scanning electron microscopy (SEM) revealed disruption in structural and morphological features. Crystallinity index (CrI) of treated rice straw increased by 15.54% in comparison to native biomass. DGB and DGS15 individually yielded 0.64 g/g and 0.82 g/g lactic acid respectively, where as their co-cultivation led to effective utilisation of both glucose and xylose within 15 h (70%) and complete utilisation in 48 h, producing 49.75 g/L LA with a yield of 0.98 g/g and productivity of 1.036 g/L/h, and resulting in reduction in fermentation time. Separate hydrolysis of rice straw and co-fermentation (SHCF) of hydrolysates by Bacillus spp. enhanced the production of lactic acid, can circumvent challenges in biorefining of lignocellulosic biomass.

Strain engineering of Bacillus coagulans with high osmotic pressure tolerance for effective L-lactic acid production from sweet sorghum juice under unsterile conditions

Open unsterile fermentation of the low-cost non-food crop, sweet sorghum, is an economically feasible lactic acid biosynthesis process. However, hyperosmotic stress inhibits microbial metabolism and lactic acid biosynthesis, and engineering strains with high osmotic tolerance is challenging. Herein, heavy ion mutagenesis combined with osmotic pressure enrichment was used to engineer a hyperosmotic-tolerant Bacillus coagulans for L-lactic acid production. The engineered strain had higher osmotic pressure tolerance, when compared with the parental strain, primarily owing to its improved properties such as cell viability, cellular antioxidant capacity, and NADH supply. In a pilot-scale open unsterile fermentation using sweet sorghum juice as a feedstock, the engineered strain produced 94 g/L L-lactic acid with a yield of 91 % and productivity of 6.7 g/L/h, and optical purity of L-lactic acid at the end of fermentation was 99.8 %. In short, this study provided effective and low-cost approach to produce polymer-grade L-lactic acid.

Optimization of the Production and Characterization of an Antifungal Protein by Bacillus velezensis Strain NT35 and Its Antifungal Activity against Ilyonectria robusta Causing Ginseng Rusty Root Rot

A biocontrol Bacillus velezensis strain, NT35, was isolated from the rhizosphere soil of ginseng, and its sterile filtrate was obtained through a 0.22 μm filter which had a significant inhibitory effect against Ilyonectria robusta, which causes rusty root rot in Panax ginseng. In order to obtain the best sterile filtrate, the medium fermentation conditions of the strain NT35 were optimized using response surface methodology (RSM), and the best composition was obtained. Therefore, the fermentation medium was composed of yeast extract powder 2.5%, cornmeal 1.5%, K2HPO4 1.5%, and (NH4)2SO4 2.5%. The optimal inoculum amount was 6%, at an initial pH value of 7.0 and culturing at 34 °C at 180 rpm. The antifungal protein 1-4-2F was obtained through precipitation via 30% (NH4)2SO4 precipitation, desalting by Sephadex G-25, ion-exchange chromatography, and gel filtration chromatography. Tricine-SDS-PAGE showed that the purified protein had a relative molecular weight of approximately 6.5 kDa. The protein 1-4-2F was relatively stable and had better antifungal activity at pH 4–10 and 20–100 °C under ultraviolet irradiation of 30 W. The amino acid sequence of protein 1-4-2F was obtained using mass spectrometry, and had 100% similarity to a hypothetical protein from B. velezensis YAU B9601-Y2 (Accession No: AFJ62117). Its molecular weight was 10.176 kDa, the isoelectric point was 9.08, and its sequence coverage reached 49%. The EC50 value of the protein 1-4-2F against I. robusta was 1.519 μg·mL−1. The mycelia morphology of I. robusta changed significantly after treatment with antifungal protein under microscopic observation; the branches of the mycelia increased, distorted, partially swelled into a spherical or elliptical shape, and even ruptured; and the cells became vacuoles.

Optimization of C50 Carotenoids Production by Open Fermentation of Halorubrum sp. HRM-150

C₅₀ carotenoids, as unique bioactive molecules, have many biological properties, including antioxidant, anticancer, and antibacterial activity, and have a wide range of potential uses in the food, cosmetic, and biomedical industries. The majority of C₅₀ carotenoids are produced by the sterile fermentation of halophilic archaea. This study aims to look at more cost-effective and manageable ways of producing C₅₀ carotenoids. The basic medium, carbon source supplementation, and optimal culture conditions for Halorubrum sp. HRM-150 C₅₀ carotenoids production by open fermentation were examined in this work. The results indicated that Halorubrum sp. HRM-150 grown in natural brine medium grew faster than artificial brine medium. The addition of glucose, sucrose, and lactose (10 g/L) enhanced both biomass and carotenoids productivity, with the highest level reaching 4.53 ± 0.32 μg/mL when glucose was added. According to the findings of orthogonal studies based on the OD₆₀₀ and carotenoids productivity, the best conditions for open fermentation were salinity 20-25%, rotation speed 150-200 rpm, and pH 7.0-8.2. The up-scaled open fermentation was carried out in a 7 L medium under optimum culture conditions. At 96 h, the OD₆₀₀ and carotenoids productivity were 9.86 ± 0.51 (dry weight 10.40 ± 1.27 g/L) and 7.31 ± 0.65 μg/mL (701.40 ± 21.51 μg/g dry weight, respectively). When amplified with both universal bacterial primer and archaeal primer in the open fermentation, Halorubrum remained the dominating species, indicating that contamination was kept within an acceptable level. To summarize, open fermentation of Halorubrum is a promising method for producing C₅₀ carotenoids.

Lactic Acid Production from Old Oil Palm Trunk Sap in the Open Batch, Open Repeated Batch, Fed-Batch, and Repeated Fed-Batch Fermentation by Lactobacillus rhamnosus ATCC 10863

The cost of fermentable sugars added as a substrate is one major problem for economic lactic acid (LA) production. Old oil palm trunks (OPT) squeezed sap, the agricultural wastes on replanting and pruning of oil palm (Elaeis guineensis), contained mainly glucose and fructose as a potential feedstock to use as a vast carbon source for LA production. To improve the LA yield and productivity, various fermentation modes were performed by Lactobacillus rhamnosus ATCC 10863 using OPT sap as a basal medium. A modified constant feed mode of fed-batch and repeated fed-batch fermentation using undiluted OPT sap feed medium can achieve a high average LA concentration of 95.94 g/L, yield of 1.04 g/g, and productivity of 6.40 g/L/h) at 11 h cultivation time. It can also provide open and open repeated batch fermentation with an average LA concentration of 91.30 g/L, yield of 0.87 g/g, and productivity of 3.88 g/L/h at 21 h fermentation time.

Conversion sweet sorghum biomass to produce value-added products

Currently, most biotechnological products are produced from sugar- or starch-containing crops via microbial conversion, but accelerating the conflict with food supply. Thus, it has become increasingly interesting for industrial biotechnology to seek alternative non-food feedstock, such as sweet sorghum. Value-added chemical production from sweet sorghum not only alleviates dependency and conflict for traditional starch feedstocks (especially corn), but also improves efficient utilization of semi-arid agricultural land resources, especially for China. Sweet sorghum is rich in components, such as fermentable carbohydrates, insoluble lignocellulosic parts and bioactive compounds, making it more likely to produce value-added chemicals. Thus, this review highlights detailed bioconversion methods and its applications for the production of value-added products from sweet sorghum biomass. Moreover, strategies and new perspectives on improving the production economics of sweet sorghum biomass utilization are also discussed, aiming to develop a competitive sweet sorghum-based economy.

Reaction kinetics of physico-chemical attributes in coconut inflorescence sap during fermentation

The study on fermentation kinetics of the coconut inflorescence sap is important to understand its shelf life at different storage conditions and to develop suitable value added products. The coconut inflorescence sap collected by using in-house developed coco-sap chiller device is called Kalparasa. The fermentation characteristics of Kalparasa were investigated at every 1-h interval under ambient (31 ± 2 °C) and refrigerated (5 ± 1 °C) storage conditions. The results reveal that pH of the sap and total sugar content decline rapidly under ambient conditions than under refrigerated conditions. Acidity, turbidity, and reducing sugar content significantly (p < 0.001) increases for the sap stored under ambient conditions. The reaction rate constant (k) of the vitamin C and total sugar degradation increases with the atmospheric fermentation. The degradation kinetics of vitamin C and total sugar in Kalparasa during natural fermentation (ambient condition) follow second-order equation whereas the reducing sugar follows the first-order equation.

Integrated and Consolidated Review of Plastic Waste Management and Bio-Based Biodegradable Plastics: Challenges and Opportunities

Cumulative plastic production worldwide skyrocketed from about 2 million tonnes in 1950 to 8.3 billion tonnes in 2015, with 6.3 billion tonnes (76%) ending up as waste. Of that waste, 79% is either in landfills or the environment. The purpose of the review is to establish the current global status quo in the plastics industry and assess the sustainability of some bio-based biodegradable plastics. This integrative and consolidated review thus builds on previous studies that have focused either on one or a few of the aspects considered in this paper. Three broad items to strongly consider are: Biodegradable plastics and other alternatives are not always environmentally superior to fossil-based plastics; less investment has been made in plastic waste management than in plastics production; and there is no single solution to plastic waste management. Some strategies to push for include: increasing recycling rates, reclaiming plastic waste from the environment, and bans or using alternatives, which can lessen the negative impacts of fossil-based plastics. However, each one has its own challenges, and country-specific scientific evidence is necessary to justify any suggested solutions. In conclusion, governments from all countries and stakeholders should work to strengthen waste management infrastructure in low- and middle-income countries while extended producer responsibility (EPR) and deposit refund schemes (DPRs) are important add-ons to consider in plastic waste management, as they have been found to be effective in Australia, France, Germany, and Ecuador.

Lactic acid production - producing microorganisms and substrates sources-state of art

Lactic acid is an organic compound produced via fermentation by different microorganisms that are able to use different carbohydrate sources. Lactic acid bacteria are the main bacteria used to produce lactic acid and among these, Lactobacillus spp. have been showing interesting fermentation capacities. The use of Bacillus spp. revealed good possibilities to reduce the fermentative costs. Interestingly, lactic acid high productivity was achieved by Corynebacterium glutamicum and E. coli, mainly after engineering genetic modification. Fungi, like Rhizopus spp. can metabolize different renewable carbon resources, with advantageously amylolytic properties to produce lactic acid. Additionally, yeasts can tolerate environmental restrictions (for example acidic conditions), being the wild-type low lactic acid producers that have been improved by genetic manipulation. Microalgae and cyanobacteria, as photosynthetic microorganisms can be an alternative lactic acid producer without carbohydrate feed costs. For lactic acid production, it is necessary to have substrates in the fermentation medium. Different carbohydrate sources can be used, from plant waste as molasses, starchy, lignocellulosic materials as agricultural and forestry residues. Dairy waste also can be used by the addition of supplementary components with a nitrogen source.

Efficient production of coenzyme Q10 from acid hydrolysate of sweet sorghum juice by Rhodobacter sphaeroides

In order to achieve efficient bioconversion of biomass-derived sugars, acid hydrolysate of sweet sorghum juice (SSJAH) containing abundant fermentable sugars was used for coenzyme Q10 (CoQ10) fermentation by Rhodobacter sphaeroides CQ-09-1. The synthesis of CoQ10 was facilitated when the initial concentration of total sugar was 80.00 g L-1. And the highest CoQ10 titer was obtained when the pH and temperature were maintained at 7.00 and 30.00 °C, respectively. Moreover, corn steep powder (CSP) was proved to be an efficient nitrogen & salt supplement to SSJAH. Under the optimized conditions, the titer of CoQ10 reached 141.95 mg L-1 in a fed-batch fermentation. The CoQ10 titer reported was about two times higher than that obtained in the previous study using wild strains. This process introduces a potential way to produce CoQ10 using the concept of biorefinery, while making full use of sweet sorghum juice (SSJ).

Production and Purification of l-lactic Acid in Lab and Pilot Scales Using Sweet Sorghum Juice

Sweet sorghum juice (SSJ) was evaluated as fermentation substrate for the production of l-lactic acid. A thermophilic Bacillus coagulans isolate was selected for batch fermentations without the use of additional nutrients. The first batch of SSJ (Batch A) resulted on higher lactic acid concentration, yield and productivity with values of 78.75 g∙L−1, 0.78 g∙g−1 and 1.77 g∙L−1 h−1, respectively. Similar results were obtained when the process was transferred into the pilot scale (50 L), with corresponding values of 73 g∙L−1, 0.70 g∙g−1 and 1.47 g∙L−1 h−1. A complete downstream process scheme was developed in order to separate lactic acid from the fermentation components. Coarse and ultra-filtration were employed as preliminary separation steps. Mono- and bipolar electrodialysis, followed by chromatography and vacuum evaporation were subsequently carried out leading to a solution containing 905.8 g∙L−1 lactic acid, with an optical purity of 98.9%. The results of this study highlight the importance of the downstream process with respect to using SSJ for lactic acid production. The proposed downstream process constitutes a more environmentally benign approach to conventional precipitation methods.

Possibility of L-(+)-lactic acid fermentation using malting, brewing, and oil production by-products

Industrial by-products such as brewer's spent grain (BSG) hydrolysate, malt rootlets extract (MRE) and soybean meal extract (SME) were used for L-(+) lactic acid (LA) production by a pure L. rhamnosus ATCC 7469 strain. The effect of the addition of MRE (10-50%) or SME (10-50%) in BSG hydrolysate on batch and fed-batch LA fermentation was evaluated. The addition of MRE and SME increased the concentration of free amino nitrogen (FAN) and essential minerals (Fe, Mg, Mn, and Zn), which had a positive effect on the fermentation. Also, the MRE addition significantly lowered C/N ration to a more favorable level for the efficient LA fermentation. In batch fermentation, the highest LA concentration (25.73 g/L), yield (86.31%), and volumetric productivity (0.95 g/L h^-1), were obtained with the addition of 50% MRE. Further increase in LA concentration to 58.01 g/L, yield to 88.54%, and volumetric productivity to 1.19 g/L h^-1 was achieved in fed-batch fermentation with addition of 50% MRE. A high optical purity of LA with 99.7% of L-(+)-isomer was obtained on the substrate based on industrial by-products. In addition, solid remains after BSG hydrolysis and MRE and SME preparation, together with the biomass of L. rhamnosus separated after the fermentation could be a good base for feed preparation.

Potential Use of Bacillus coagulans in the Food Industry

Probiotic microorganisms are generally considered to beneficially affect host health when used in adequate amounts. Although generally used in dairy products, they are also widely used in various commercial food products such as fermented meats, cereals, baby foods, fruit juices, and ice creams. Among lactic acid bacteria, Lactobacillus and Bifidobacterium are the most commonly used bacteria in probiotic foods, but they are not resistant to heat treatment. Probiotic food diversity is expected to be greater with the use of probiotics, which are resistant to heat treatment and gastrointestinal system conditions. Bacillus coagulans (B. coagulans) has recently attracted the attention of researchers and food manufacturers, as it exhibits characteristics of both the Bacillus and Lactobacillus genera. B. coagulans is a spore-forming bacterium which is resistant to high temperatures with its probiotic activity. In addition, a large number of studies have been carried out on the low-cost microbial production of industrially valuable products such as lactic acid and various enzymes of B. coagulans which have been used in food production. In this review, the importance of B. coagulans in food industry is discussed. Moreover, some studies on B. coagulans products and the use of B. coagulans as a probiotic in food products are summarized.

Efficient production of high-molecular-weight hyaluronic acid with a two-stage fermentation

A two-stage fermentation process with a segmented control strategy provides high-level synthesis in both HA titer and molecular weight.

Lignocentric analysis of a carbohydrate-producing lignocellulosic biorefinery process

A biologically-based lignocellulosic biorefinery process for obtaining carbohydrates from raw biomass was investigated across six diverse biomasses (three hardwoods & three nonwoods) for the purpose of decoding lignin's influence on sugar production. Acknowledging that lignin could positively alter the economics of an entire process if valorized appropriately, we sought to correlate the chemical properties of lignin within the process to the traditional metrics associated with carbohydrate production-cellulolytic digestibility and total sugar recovery. Based on raw carbohydrate, enzymatic recovery ranged from 40 to 64% w/w and total recovery ranged from 70 to 87% w/w. Using nitrobenzene oxidation to quantify non-condensed lignin structures, it was found that raw hardwoods bearing increasing non-condensed S/V ratios (2.5-5.1) render increasing total carbohydrate recovery from hardwood biomasses. This finding indicates that the chemical structure of hardwood lignin influences the investigated biorefinery process' ability to generate carbohydrates from a given raw hardwood feedstock.

Non-sterile fermentations for the economical biochemical conversion of renewable feedstocks

Heavy reliance on petroleum-based products drives continuous exploitation of fossil fuels, and results in serious environmental and climate problems. To address such an issue, there is a shift from petroleum sources to renewable ones. Biochemical conversion via fermentation is a primary platform for converting renewable sources to biofuels and bulk chemicals. In order to provide cost-competitive alternatives, it is imperative to develop efficient, cost-saving, and robust fermentation processes. Non-sterile fermentation offers several benefits compared to sterile fermentation, including elimination of sterility, reduced maintenance requirements, relatively simple bioreactor design, and simplified operation. Thus, cost effectiveness of non-sterile fermentation makes it a practical platform for low cost, large volume production of biofuels and bulk chemicals. Many approaches have been developed to conduct non-sterile fermentation without sacrificing the yields and productivities of fermentation products. This review focuses on the strategies for conducting non-sterile fermentation. The challenges facing non-sterile fermentation are also discussed.

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass-carbohydrates, lipids, and proteins-there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage.