High-yield spore production from Bacillus licheniformis by solid state fermentation

Bacillus genus industrial applications and innovation: First steps towards a circular bioeconomy

In recent decades, environmental concerns have directed several policies, investments, and production processes. The search for sustainable and eco-friendly strategies is constantly increasing to reduce petrochemical product utilization, fossil fuel pollution, waste generation, and other major ecological impacts. The concepts of circular economy, bioeconomy, and biorefinery are increasingly being applied to solve or reduce those problems, directing us towards a greener future. Within the biotechnology field, the Bacillus genus of bacteria presents extremely versatile microorganisms capable of producing a great variety of products with little to no dependency on petrochemicals. They are able to grow in different agro-industrial wastes and extreme conditions, resulting in healthy and environmentally friendly products, such as foods, feeds, probiotics, plant growth promoters, biocides, enzymes, and bioactive compounds. The objective of this review was to compile the variety of products that can be produced with Bacillus cells, using the concepts of biorefinery and circular economy as the scope to search for greener alternatives to each production method and providing market and bioeconomy ideas of global production. Although the genus is extensively used in industry, little information is available on its large-scale production, and there is little current data regarding bioeconomy and circular economy parameters for the bacteria. Therefore, as this work gathers several products' economic, production, and environmentally friendly use information, it can be addressed as one of the first steps towards those sustainable strategies. Additionally, an extensive patent search was conducted, focusing on products that contain or are produced by the Bacillus genus, providing an indication of global technology development and direction of the bacteria products. The Bacillus global market represented at least $18 billion in 2020, taking into account only the products addressed in this article, and at least 650 patent documents submitted per year since 2017, indicating this market's extreme importance. The data we provide in this article can be used as a base for further studies in bioeconomy and circular economy and show the genus is a promising candidate for a greener and more sustainable future.

Endospore production of Bacillus spp. for industrial use

The increased occurrence of antibiotic resistance and the harmful use of pesticides are a major problem of modern times. A ban on the use of antibiotics as growth promoters in animal breeding has put a focus on the probiotics market. Probiotic food supplements are versatile and show promising results in animal and human nutrition. Chemical pesticides can be substituted by biopesticides, which are very effective against various pests in plants due to increased research. What these fields have in common is the use of spore-forming bacteria. The endospore-forming Bacillus spp. belonging to this group offer an effective solution to the aforementioned problems. Therefore, the biotechnological production of sufficient qualities of such endospores has become an innovative and financially viable field of research. In this review, the production of different Bacillus spp. endospores will be reviewed. For this purpose, the media compositions, cultivation conditions and bioprocess optimization methods of the last 20 years are presented and reflected.

Production and Optimization of Conjugated Linoleic and Eicosapentaenoic Acids by Bifidobacterium lactis in Cold-Pressed Soybean Cake

Background and Purpose

In regard to the biosynthesis of conjugated linoleic acid (CLA) and eicosapentaenoic acid (EPA) by some bacteria, the objective of this study was to evaluate the efficiency of solid-state fermentation based on soybean pressed cake (SPC) to produce CLA and EPA by Bifidobacterium lactis. The objective of this study was to evaluate the efficiency of solid-state fermentation based on SPC to produce CLA and EPA by B. lactis.

Methods

Process conditions including humidity, inoculation level, and temperature parameters were optimized by adopting the response surface methodology (RSM) method (response surface method) and the design expert software. Accordingly, a homogeneous SPC paste substrate at 60, 70, and 80% humidity was prepared with different inoculation levels at 30, 37, and 44°C to assess the strain behavior. The introduced SPC consisted of 60% humidity, 2% inoculation level at 37°C, and 60% humidity, and 4% inoculation level at 30 and 44°C; it also included 6% inoculation level at 37°C, 70% humidity at 2% inoculation level, at 30 and 44°C, and 4% inoculation level at 37°C. Also, SPC with 80% humidity at 2% and 4% inoculation levels, and at 30 and 44°C was obtained. To confirm the accuracy of the conditions, an experiment was conducted according to the defined requirements.

Results

The results were compared with the predicted data, which showed a significant difference. Under optimized conditions, with an inoculation level of 4% on the SPC medium with 70% humidity and at 37°C, B. lactis strains could yield 9cis-, 11 trans-linoleic and eicosapentaenoic at 0.18 and 0.39% of the total fatty acids.

Conclusion

So, the potential benefits of using SPC as an inexpensive substrate for the commercial production of CLA and EPA should be noted.

Optimization of Soybean Meal Fermentation for Aqua-Feed with Bacillus subtilis natto Using the Response Surface Methodology

This study aimed to improve the nutritional value of soybean meal (SBM) by solid-state fermentation (SSF) using Bacillus subtilis natto (B. s. natto) to overcome the limitations of SBM usage in aquafeed. The response surface methodology (RSM) was employed to explore the relationships of fermentation conditions, such as temperature, time, water-substrate ratio, and layer thickness, on the degree of protein hydrolysis (DH) and the crude protein (CP) content. The optimum conditions for achieving the higher DH (15.96%) and CP (55.76%) were 43.82 °C, 62.32 h, 1.08 of water-substrate ratio, and a layer thickness of 2.02 cm. CP and DH in the fermented soybean meal (FSM) increased by 9.8% and 177.1%, respectively, and crude fiber decreased by 14.1% compared to SBM. The protein dispersibility index (PDI) decreased by 29.8%, while KOH protein solubility (KPS) was significantly increased by 17.4%. Flavonoids and total phenolic acid content in FSM were increased by 231.0% and 309.4%, respectively. Neutral protease activity (NPA) also reached a high level (1723.6 U g−1). Total essential amino acids (EAA) in FSM increased by 12.2%, higher than the 10.8% increase of total non-essential amino acids (NEAA), while the total free amino acids content was 12.76 times higher than that of SBM. Major anti-nutritional factors in SBM were significantly reduced during the process, and almost all SBM protein macromolecules were decomposed. Together with the cost-effectiveness of SSF, B. s. natto-fermented SBM products have great potential to improve the plant composition and replace high-cost ingredients in aquafeed, contributing to food security and environmental sustainability.

A Review of the Effects and Production of Spore-Forming Probiotics for Poultry

Simple Summary

Spore-forming probiotics are widely used in the poultry industry for their beneficial impact on host health. The main feature that separates spore-forming probiotics from the more common lactic acid probiotics is their high resistance to external and internal factors, resulting in higher viability in the host and correspondingly, greater efficiency. Their most important effect is the ability to confront pathogens, which makes them a perfect substitute for antibiotics. In this review, we cover and discuss the interactions of spore-forming probiotic bacteria with poultry as the host, their health promotion effects and mechanisms of action, impact on poultry productivity parameters, and ways to manufacture the probiotic formulation. The key focus of this review is the lack of reproducibility in poultry research studies on the evaluation of probiotics’ effects, which should be solved by developing and publishing a set of standard protocols in the professional community for conducting probiotic trials in poultry.

Abstract

One of the main problems in the poultry industry is the search for a viable replacement for antibiotic growth promoters. This issue requires a “one health” approach because the uncontrolled use of antibiotics in poultry can lead to the development of antimicrobial resistance, which is a concern not only in animals, but for humans as well. One of the promising ways to overcome this challenge is found in probiotics due to their wide range of features and mechanisms of action for health promotion. Moreover, spore-forming probiotics are suitable for use in the poultry industry because of their unique ability, encapsulation, granting them protection from the harshest conditions and resulting in improved availability for hosts’ organisms. This review summarizes the information on gastrointestinal tract microbiota of poultry and their interaction with commensal and probiotic spore-forming bacteria. One of the most important topics of this review is the absence of uniformity in spore-forming probiotic trials in poultry. In our opinion, this problem can be solved by the creation of standards and checklists for these kinds of trials such as those used for pre-clinical and clinical trials in human medicine. Last but not least, this review covers problems and challenges related to spore-forming probiotic manufacturing.

Bacillus subtilis natto as a potential probiotic in animal nutrition

The growing global demand for animal products and processed meat has created a challenge for the livestock sector to enhance animal productivity without compromising product quality. The restriction of antibiotics in animal feeds as growth promoters makes the use of probiotics a natural and safe alternative to obtain functional foods that provide animal health and quality and to maintain food safety for consumers. To incorporate these additives into the diet, detailed studies are required, in which in vitro and in vivo assays are used to prove the efficacy and to ensure the safety of probiotic candidate strains. Studies on the use of Bacillus subtilis natto as a spore-forming probiotic bacterium in animal nutrition have shown no hazardous effects and have demonstrated the effectiveness of its use as a probiotic, mainly due to its proven antimicrobial, anti-inflammatory, antioxidant, enzymatic, and immunomodulatory activity. This review summarizes the recent scientific background on the probiotic effects of B. subtilis natto in animal nutrition. It focuses on its safety assessment, host-associated efficacy, and industrial requirements.

Improved Production of Spores and Bioactive Metabolites from Bacillus amyloliquefaciens in Solid-state Fermentation by a Rapid Optimization Process

A dipicolonic acid fluorimetry assay was used instead of plate counting for the assessment of spore yields for enhanced optimization efficiency. The associated parameters, including the ratio of solid substrates, composition of liquid substrates, and cultivation conditions, were systematically optimized in a shake-flask culture. The maximum spore yield of 7.24 × 10¹⁰ CFU/g of wet substrate was achieved. The optimization process produced a 25.7-fold increase in spore yields compared with those before optimization. In addition, the maximum release of bioactive metabolites during spore accumulation was subsequently obtained with 573.0 U/g of protease, 188.8 U/g of amylase, 186.8 U/g of cellulase, and 3.45 mg/g of acid-soluble protein. The experiment provides a methodological basis for the rapidly optimized production of Bacillus spores in pure solid-state fermentation.

Recent Advances in the Physiology of Spore Formation for Bacillus Probiotic Production

Spore-forming probiotic bacteria have received a wide and constantly increasing scientific and commercial interest. Among them, Bacillus species are the most studied and well-characterized Gram-positive bacteria. The use of bacilli as probiotic products is expanding especially rapidly due to their inherent ability to form endospores with unique survivability and tolerance to extreme environments and to produce a large number of valuable metabolites coupled with their bio-therapeutic potential demonstrating immune stimulation, antimicrobial activities and competitive exclusion. Ease of Bacillus spp. production and stability during processing and storage make them a suitable candidate for commercial manufacture of novel foods or dietary supplements for human and animal feeds for livestock, especially in the poultry and aquaculture industries. Therefore, the development of low-cost and competitive technologies for the production of spore-forming probiotic bacteria through understanding physiological peculiarities and mechanisms determining the growth and spore production by Bacillus spp. became necessary. This review summarizes the recent literature and our own data on the physiology of bacilli growth and spore production in the submerged and solid-state fermentation conditions, focusing on the common characteristics and unique properties of individual bacteria as well as on several approaches providing enhanced spore formation.

Method of preparation, visualization and ultrastructural analysis of a formulation of probiotic Bacillus subtilis KATMIRA1933 produced by solid-phase fermentation

Probiotic preparations are used in medical treatment and in agricultural practice. They modulate numerous activities in eukaryotic hosts, such as: inhibition of pathogenic microbiota; stimulation of immunological responses; and production of antioxidants, anti-mutagens, and DNA protectors. Also, probiotic bacteria are used as a preventive measure to prevent bacterial diseases of the gastrointestinal tract. Solid-phase fermentation is reported as being used in the production of probiotic formulations where a solid substratum, such as soy and oil meal, is utilized for the growth of beneficial microorganisms. However, there are insufficient reports in the literature related to methodological approaches enabling evaluation of the final products of solid-phase fermentation. We suggest a novel method enabling evaluation of probiotic solid-state fermentation dry powders and observation of their morphology, ultrastructure, and elucidation of the quantitative distribution of probiotic microorganisms in solid substrates using electron microscopy. •The method is intended for ultrastructure microphotography of dry substances - for example, ultrastructure of solid-phase fermentation products.•The method allows preserving the ultrastructure of substrates that are damaged when soaking.•The method does not require additional equipment and reagents and can be used in all laboratories using electron microscopy.

Optimization of Mixed Solid-state Fermentation of Soybean Meal by Lactobacillus Species and Clostridium butyricum

Soybean meal is the main vegetable protein source in animal feed. Soybean meal contains several anti-nutritional factors, which directly affect digestion and absorption of soy protein, thereby reducing growth performance and value in animals. Fermented soybean meal is rich in probiotics and functional metabolites, which facilitates soybean protein digestion, absorption and utilization in piglets. However, the mixed solid-state fermentation (SSF) conditions of soybean meal remain to be optimized. In this study, we investigated the optimal parameters for SSF of soybean meal by Lactobacillus species and Clostridium butyricum . The results showed that two days of fermentation was sufficient to increase the viable count of bacteria, lactic acid levels and degradation of soybean protein in fermented soybean meal at the initial moisture content of 50%. The pH value, lowering sugar content and oligosaccharides in fermented soybean meal, was significantly reduced at the initial moisture content of 50% after two days of fermentation. Furthermore, the exogenous proteases used in combination with probiotics supplementation were further able to enhance the viable count of bacteria, degradation of soybean protein and lactic acid level in the fermented soybean meal. In addition, the pH value and sugar content in fermented soybean meal were considerably reduced in the presence of both proteases and probiotics. Furthermore, the fermented soybean meal also showed antibacterial activity against Staphylococcus aureus and Escherichia coli . These results together suggest that supplementation of both proteases and probiotics in SSF improves the nutritional value of fermented soybean meal and this is suitable as a protein source in animal feed.

Rapid and simple detection of endospore counts in probiotic Bacillus cultures using dipicolinic acid (DPA) as a marker

Spore counting in probiotic Bacillus cultures using dipicolinic acid (DPA) as a marker was studied for developing a rapid and simple detection method. The newly developed method is based on the fluorescence enhancement by a new chelating agent, which forms a complex with EuCl₃ and DPA. The results showed that 1,2-cyclohexanediamine-N,N,N′N′-tetraacetic acid (CyDTA) greatly enhanced the fluorescence intensity in all selected chelating agents. The optimal composition of the fluorescence complex DPA-Eu-CyDTA had a detection limit of 0.3 nM of DPA. Metal ions in high concentrations, including Cu²⁺, Fe²⁺, Fe³⁺, Al³⁺, and Zn²⁺, might lower the detection sensitivity, which could be eliminated by diluting the sample with the metal ions below 10 μM. The maximum release of DPA was achieved by heating treatments at 121 °C for at least 10 min for two types of Bacillus endospores. The spore concentrations and corresponding released DPA fluorescence intensities were linearly associated (coefficient R² = 0.9993 and 0.9995 for Bacillus subtilis MA139 and Bacillus licheniformis BL20386, respectively). The detection limit for both strains reached approximately 6800 spores/mL. The verification results showed that the DPA fluorimetry assay developed in the present study was fully consistent with the plate-counting assay. The study shows that the fluorescence complex DPA-Eu-CyDTA can be reliably used for the detection of endospores in Bacillus fermentation for the production of probiotics.

The use of a simple flow cytometry method for rapid detection of spores in probiotic Bacillus licheniformis-containing tablets

Detection of the number of vegetative cells and endospores is necessary for quality control during the production of orally administered probiotic Bacillus licheniformis-containing tablets (BCT). However, there is no standard method for the rapid detection of vegetative cells and endospores in China. In this study, a simple flow cytometry (FCM) method was used to monitor the population dynamics of BCT. Using a specific fluorescent stain, SYBR green I, flow cytometric analysis could easily differentiate two morphological states of B. licheniformis. Compared with plate count assay (PCA) for determining the number of vegetative cells and endospores, the percentage of endospores determined by FCM was ~10% higher than that by PCA. Advantages of the FCM method over conventional methods include lower labor work, shorter detection time, and higher accuracy. Therefore, this simple FCM method could be a practical tool for monitoring quality control during the production of probiotic BCT.

Protein production by Arthrospira (Spirulina) platensis in solid state cultivation using sugarcane bagasse as support

The genus Arthrospira comprises a group of filamentous multicellular cyanobacteria and can be used for animal feed and human food. Solid state fermentation or cultivation (SSF) involves the use of a culture medium composed of solid material with given moisture content. No studies have been published about the cultivation of microalgae or cyanobacteria on solid medium. Furthermore, although sugar-cane bagasse is used as source of energy in alcohol distilleries in Brazil, the excess could be a support to photosynthetic microorganism growth. The experimental design methodology was used to evaluate the protein production by Arthrospira platensis under SSF using sugarcane bagasse as support, taking into account the moisture content of the medium, light intensity and inoculum concentration. Moisture was found to have a strong influence on the performance of the process. The best conditions were: moisture of 98.8%; inoculum concentration of 0.15 g biomass·kg wet culture medium-1 and light intensity of 6.0 klx.

Development of a low-cost sterilization biological indicator using Bacillus atrophaeus by solid-state fermentation

The production of biological indicators involving bacterial sporulation and multi-step downstream processes has been described. The goal of the present work was to use fermented material as the final product in a biological indicator, thereby reducing processing steps and costs. The performance of three different inexpensive supports (vermiculite, sand, and sugarcane bagasse) was assessed by determining Bacillus atrophaeus sporulation during solid-state fermentation and by assessing the direct use of the fermentation products in the subsequent steps of the process. All three supports allowed spore production of between 10(7) and 10(9) CFU g(-1). Sand proved to be the best inert support enabling the direct use of the fermented product due to its easy homogenization, filling properties, and compatibility with recovery medium. Bacterial adhesion to the sand surface was supported by biofilm formation. The resistance to sterilization of the dried fermentation product was evaluated. For dry-heat resistance (160°C), the D value was 6.6 min, and for ethylene oxide resistance (650 mg/L), the D value was 6.5 min. The cost reduction of this process was at least 48%. No previous studies have been published on the application of sand as a support in solid-state fermentation for the production of biological indicators.

Effect of potential multimicrobe probiotic product processed by high drying temperature and antibiotic on performance of weanling pigs

In this study, the effect of a potential multimicrobe probiotic subjected to high-temperature drying was investigated. Potential multimicrobe probiotics produced by solid substrate fermentation were dried at low (LT, 40°C for 72 h) or high (HT, 70°C for 36 h) temperature. In Exp. 1, 288 weaned pigs (BW, 6.43 ± 0.68 kg) were allotted to 4 treatments on the basis of BW (4 pens per treatment with 18 pigs in each pen). Dietary treatments were negative control (NC; basal diet without any antimicrobial), positive control (PC; basal diet + 0.1% chlortetracycline), basal diet with 0.3% probiotic LT, and basal diet with 0.3% probiotic HT. Diets were fed in 2 phases, phase I (d 0 to 14) and phase II (d 15 to 28); and growth performance, apparent total tract digestibility (ATTD, d 28), and fecal microflora (d 14 and 28) were evaluated. Over the 28-d trial, pigs fed PC and probiotic diets had greater ADG (P < 0.001), ADFI (P < 0.05), and G:F (P < 0.01) than pigs fed NC diet. The ATTD of DM and GE was greater (P < 0.05) in pigs fed probiotic diets when compared with pigs fed the NC diet. At d 28, fewer Clostridia (P < 0.01) were identified in the feces of pigs fed PC and probiotic diets than pigs fed the NC diet. However, the performance, ATTD of DM and GE, and fecal Clostridia population were similar among pigs fed probiotic LT and HT diets. In Exp. 2, 288 weaned pigs (initial BW, 5.84 ± 0.18 kg) were allotted to 4 treatments in a 2 × 2 factorial arrangement on the basis of BW. The effects of 2 levels of probiotic HT (0.30 or 0.60%), each with or without antibiotic (chlortetracycline, 0 or 0.1%), on performance, ATTD, intestinal morphology, and fecal and intestinal microflora were investigated. Feeding of 0.60% probiotic HT diet improved (P < 0.05) overall ADG, ATTD of DM and GE, and Lactobacillus population in the feces and intestine, and reduced the population of Clostridium and coliforms in feces (d 14) and ileum. Inclusion of antibiotic improved (P < 0.05) the overall ADG, ADFI, and ATTD of DM at d 14 and reduced fecal Clostridium population at d 28. Increased (P < 0.05) villus height at jejunum and ileum, and villus height:crypt depth at the ileum was noticed in pigs fed 0.60% probiotic HT and antibiotic diets. In conclusion, high drying temperature had no effect on the efficacy of potential multimicrobe probiotic product. However, the probiotic product dried at high temperature was more effective at 0.60% inclusion, whereas inclusion of an antibiotic improved pig performance but did not show any interaction with probiotics.

Greater enhancement of Bacillus subtilis spore yields in submerged cultures by optimization of medium composition through statistical experimental designs

Bacillus subtilis spore preparations are promising probiotics and biocontrol agents, which can be used in plants, animals, and humans. The aim of this work was to optimize the nutritional conditions using a statistical approach for the production of B. subtilis (WHK-Z12) spores. Our preliminary experiments show that corn starch, corn flour, and wheat bran were the best carbon sources. Using Plackett-Burman design, corn steep liquor, soybean flour, and yeast extract were found to be the best nitrogen source ingredients for enhancing spore production and were studied for further optimization using central composite design. The key medium components in our optimization medium were 16.18 g/l of corn steep liquor, 17.53 g/l of soybean flour, and 8.14 g/l of yeast extract. The improved medium produced spores as high as 1.52 +/- 0.06 x 10(10) spores/ml under flask cultivation conditions, and 1.56 +/- 0.07 x 10(10) spores/ml could be achieved in a 30-l fermenter after 40 h of cultivation. To the best of our knowledge, these results compared favorably to the documented spore yields produced by B. subtilis strains.

Bioremediation of reclaimed wastewater used as landscape water by using the denitrifying bacterium Bacillus cereus

Organic matter and nitrogen removal from reclaimed wastewater used as landscape water was carried out by in situ bioremediation. A denitrifying bacterium Bacillus cereus DNF409 was introduced for this purpose, and the amount of B. cereus used was optimized. The total nitrogen (TN) content and chemical oxygen demand (COD) of the landscape water decreased from 9.86 to 3.1 mg/L (removal rate, 68.6%) and from 127 to 36 mg/L (removal rate, 71.7%). The transparency of water increased from 0.2 to 0.55 m.