Solid-state fermentation of Bacillus thuringiensis var kurstaki HD-73 maintains higher biomass and spore yields as compared to submerged fermentation using the same media

Comparison of primary and secondary metabolites and antioxidant activities by solid-state fermentation of Apios americana Medikus with different fungi

This study compared the nutritional components, isoflavones, and antioxidant activities by solid-sate fermentation of Apios americana Medikus (AAM) with seven different fungi. The total fatty acid contents increased from 120.5 mg/100 g (unfermented AAM, UFAAM) to 242.0 to 3167.5 mg/100 g (fermented AAM, FAAM) with all fungi. In particular, the values of total fatty acids were highest (26.3-fold increase) in the FAAM with Monascus purpureus. The amount of total free amino acids increased from 591.69 mg/100 g (UFAAM) to 664.38 to 1603.07 mg/100 g after fermentation except for Monascus pilosus and Lentinula edodes. The total mineral contents increased evidently after fermentation with M. purpureus, F. velutipes, and Tricholoma matsutake (347.36 → 588.29, 576.59, and 453.32 mg/100 g, respectively). The UFAAM predominated isoflavone glycosides, whereas glycoside forms were converted into aglycone forms after fermentation by fungi. The bioconversion rates of glycoside to aglycone were excellent in the FAAM with M. pilosus, M. purpureus, F. velutipes, and T. matsutake (0.01 → 0.69, 0.50, 0.27, and 0.31 mg/g, respectively). Furthermore, the total phenolic contents, total flavonoid contents, and antioxidant activities by the abovementioned FAAM were high except for L.edodes. This FAAM can be used as a potential food and pharmaceutical materials.

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.

Anthrax revisited: how assessing the unpredictable can improve biosecurity

B. anthracis is one of the most often weaponized pathogens. States had it in their bioweapons programs and criminals and terrorists have used or attempted to use it. This study is motivated by the narrative that emerging and developing technologies today contribute to the amplification of danger through greater easiness, accessibility and affordability of steps in the making of an anthrax weapon. As states would have way better preconditions if they would decide for an offensive bioweapons program, we focus on bioterrorism. This paper analyzes and assesses the possible bioterrorism threat arising from advances in synthetic biology, genome editing, information availability, and other emerging, and converging sciences and enabling technologies. Methodologically we apply foresight methods to encourage the analysis of contemporary technological advances. We have developed a conceptual six-step foresight science framework approach. It represents a synthesis of various foresight methodologies including literature review, elements of horizon scanning, trend impact analysis, red team exercise, and free flow open-ended discussions. Our results show a significant shift in the threat landscape. Increasing affordability, widespread distribution, efficiency, as well as ease of use of DNA synthesis, and rapid advances in genome-editing and synthetic genomic technologies lead to an ever-growing number and types of actors who could potentially weaponize B. anthracis. Understanding the current and future capabilities of these technologies and their potential for misuse critically shapes the current and future threat landscape and underlines the necessary adaptation of biosecurity measures in the spheres of multi-level political decision making and in the science community.

A 3D printed plastic frame deeply impacts yeast cell growth

Solid State Fermentation (SSF) processes have been explored for yeast growth and protein and metabolites production. However, most of these processes lack standardization. In this work, we present a polylactic acid (PLA) 3D printed matrix that dramatically enhances yeast growth when embedded in liquid media compared to equivalent static cultures, and changes yeast expression patterns at the proteome level (data are available via ProteomeXchange with identifier PXD043759). Moreover, differences in sugar assimilation and ethanol production, as the main product of alcoholic fermentation, are observed. Our results suggest that these matrixes may be useful for a vast range of biotechnological applications based on yeast fermentation.

Solid-State Fermentation: Applications and Future Perspectives for Biostimulant and Biopesticides Production

With the expansion of the green products market and the worldwide policies and strategies directed toward a green revolution and ecological transition, the demand for innovative approaches is always on the rise. Among the sustainable agricultural approaches, microbial-based products are emerging over time as effective and feasible alternatives to agrochemicals. However, the production, formulation, and commercialization of some products can be challenging. Among the main challenges are the industrial production processes that ensure the quality of the product and its cost on the market. In the context of a circular economy, solid-state fermentation (SSF) might represent a smart approach to obtaining valuable products from waste and by-products. SSF enables the growth of various microorganisms on solid surfaces in the absence or near absence of free-flowing water. It is a valuable and practical method and is used in the food, pharmaceutical, energy, and chemical industries. Nevertheless, the application of this technology in the production of formulations useful in agriculture is still limited. This review summarizes the literature dealing with SSF agricultural applications and the future perspective of its use in sustainable agriculture. The survey showed good potential for SSF to produce biostimulants and biopesticides useful in agriculture.

Relationship between lipopeptide biosurfactant and primary metabolite production by Bacillus strains in solid-state and submerged fermentation

The relationship between lipopeptide and primary metabolite production by Bacillus spp. in solid-state fermentation (SSF) and submerged fermentation (SmF) was evaluated. Four wild-type strains and one mutant strain (unable to develop biofilm) were assessed in SSF and SmF, using a defined medium and polyurethane foam as inert support for SSF. Strain ATCC 21,332 in SSF presented the highest lipopeptide production. The wild-type strains revealed higher lipopeptide and biomass production and lower synthesis of primary metabolites in SSF than in SmF. However, the mutant strain showed a slightly higher production of primary metabolites in SSF than in SmF. Carbon balance analysis showed that the carbon flux was mainly directed to lipopeptides in SSF, whereas in SmF, it was directed to the production of primary metabolites and the carbon flux to lipopeptides is inversely related to primary metabolites in both types of cultures.

Valorization of Brewers’ Spent Grains: Pretreatments and Fermentation, a Review

Brewers’ spent grains constitute a valuable byproduct of the beer industry. They are characterized by a rich nutritional composition consisting of around 70% lignocellulosic fibrous material, 20% proteins, 10% lipids, in addition to vitamins, minerals, amino acids, and phenolic compounds. These spent grains are produced in large amounts all through the year, are cheap, and lack economically feasible applications. Nowadays, 70% of these spent grains are used as animal feed, 10% are used for biogas production, and the remaining 20% are disposed in landfills. Due to the aforementioned facts, alternative uses of the brewers’ spent grains are highly sought-after. In fact, this nutrient-rich industrial by-product makes it a very good candidate for valorization through biotechnological processing, particularly microbial fermentation. After applying the needed pretreatments, using brewers’ spent grains as a substrate in submerged and solid-state fermentation of different microorganisms leads to the production of various value-added compounds such as organic acids, amino acids, volatile fatty acids, enzymes, vitamins, second-generation biofuels and other products.

Polyurethane foam as an inert support using concentrated media improves quality and spore production from Bacillus thuringiensis

Bacillus thuringiensis (Bt) (Bacillales:Bacillaceae) is a gram-positive bacterium that produces spores, several virulence factors and insecticidal toxins, making this microorganism the most used biopesticide worldwide. The use of inert supports such as polyurethane foam (PUF) in solid cultures has been a great alternative to produce various metabolites, including those produced by Bt. In this study we compared the yields, productivity and quality of the spores by two wild strains of Bt, (Y15 and EA3), grown in media with high substrate concentration in both culture systems: liquid and solid (PUF as solid inert support). Both strains showed 2.5- to 30-fold increases in spore production and productivity in solid culture, which showed an even greater increase when considering the spores retained in the PUF observed by scanning electron microscopy. Moreover, spore produced in solid culture showed up to sevenfold higher survival after a heat-shock treatment, relative to spores from liquid culture. The infectivity against larvae of Galleria mellonella (Lepidoptera:Pyralidae) improved also in spores from solid cultures. This comparison showed that the culture of Bt on solid support has clear advantages over liquid culture in terms of the production and quality of spores, and that those advantages can be attributed only to the culture system, as the same media composition was used in both systems.

Physiological and Genomic Analysis of Bacillus pumilus UAMX Isolated from the Gastrointestinal Tract of Overweight Individuals

The study aimed to evaluate the metabolism and resistance to the gastrointestinal tract conditions of Bacillus pumilus UAMX (BP-UAMX) isolated from overweight individuals using genomic tools. Specifically, we assessed its ability to metabolize various carbon sources, its resistance to low pH exposure, and its growth in the presence of bile salts. The genomic and bioinformatic analyses included the prediction of gene and protein metabolic functions, a pan-genome and phylogenomic analysis. BP-UAMX survived at pH 3, while bile salts (0.2-0.3% w/v) increased its growth rate. Moreover, it showed the ability to metabolize simple and complex carbon sources (glucose, starch, carboxymethyl-cellulose, inulin, and tributyrin), showing a differentiated electrophoretic profile. Genome was assembled into a single contig, with a high percentage of genes and proteins associated with the metabolism of amino acids, carbohydrates, and lipids. Antibiotic resistance genes were detected, but only one beta-Lactam resistance protein related to the inhibition of peptidoglycan biosynthesis was identified. The pan-genome of BP-UAMX is still open with phylogenetic similarities with other Bacillus of human origin. Therefore, BP-UAMX seems to be adapted to the intestinal environment, with physiological and genomic analyses demonstrating the ability to metabolize complex carbon sources, the strain has an open pan-genome with continuous evolution and adaptation.

Solid-state culture of Azospirillum brasilense: a reliable technology for biofertilizer production from laboratory to pilot scale

A biofertilizer of Azospirillum brasilense was produced in solid-state culture (SSC) from laboratory to pilot scale. Similar operation conditions (continuous aeration and mild intermittent mixing) and two dimensionless numbers with similar L/D ratio and a similar working volume were applied to reach a scale-up factor of 75. An innovative bioreactor with rotating helical ribbons (15 kg wet matter) was used at pilot scale. A mathematical model was proposed and validated to evaluate the respirometry trends at laboratory and pilot scale exhibiting similar behavior. The cell viability was (1.3 ± 0.4) × 10⁹ and (1.3 ± 0.3) × 10⁹ colony-forming units per gram of initial dry mass at laboratory and pilot scale, at 36 and 43 h, respectively. A. brasilense maintains its viability twelve months of storage at 4 and 30 °C. This is the first report of A. brasilense being cultivated in SSC under controlled conditions. SSC processes involving unicellular microorganisms with tolerance to agitation are a promising technology to produce biofertilizers.

Bacillus licheniformis-Fermented Products Improve Growth Performance and Intestinal Gut Morphology in Broilers under Clostridium perfringens Challenge

Necrotic enteritis caused by Clostridium perfringens has reemerged as a severe poultry disease worldwide since the ban on the routine use of antibiotics in animal feed. Probiotics are considered alternatives to antibiotic growth promoters. Bacillus species are the most common microorganisms used as probiotics in the feed industry. The current study investigated the growth and surfactin levels of Bacillus licheniformis in solid-state fermentation using different substrates and evaluated the effects of B. licheniformis-fermented products on growth performance and intestinal morphology in broilers exposed to C. perfringens. The highest viable biomass and surfactin concentration of B. licheniformis-fermented products was observed at 2% molasses and 20% soybean meal supplementation during fermentation (P<0.05). B. licheniformis-fermented product-derived surfactin inhibited the growth of C. perfringens in vitro in a dose dependent manner (P<0.05). B. licheniformis-fermented product supplementation (2 g/kg) significantly improved the body weight and average daily gain weight of broilers challenged with C. perfringens (P<0.05). B. licheniformis-fermented products significantly alleviated necrotic lesions and ameliorated intestinal morphology in broilers exposed to C. perfringens (P<0.05). Collectively, these observations demonstrate that B. licheniformis-fermented products improve growth performance and gut morphology in broilers under C. perfringens challenge. B. licheniformis-fermented products may have the potential to be used as alternatives to antibiotic growth promoters for preventive treatments against C. perfringens in broilers.

Differential Activation of Ferulic Acid Catabolic Pathways of Amycolatopsis sp. ATCC 39116 in Submerged and Surface Cultures

Amycolatopsis sp. ATCC 39116 catabolizes ferulic acid by the non-oxidative deacetylation and β-oxidation pathways to produce vanillin and vanillic acid, respectively. In submerged culture, vanillin productivity decreased more than 8-fold, when ferulic, p-coumaric, and caffeic acids were employed in pre-cultures of the microorganism in order to activate the ferulic acid catabolic pathways, resulting in a carbon redistribution since vanillic acid and guaiacol productivities increased more than 5-fold compared with control. In contrast, in surface culture, the effects of ferulic and sinapic acids in pre-cultures were totally opposite to those of the submerged culture, directing the carbon distribution into vanillin formation. In surface culture, more than 30% of ferulic acid can be used as carbon source for other metabolic processes, such as ATP regeneration. In this way, the intracellular ATP concentration remained constant during the biotransformation process by surface culture (100 μg ATP/mg protein), demonstrating a high energetic state, which can maintain active the non-oxidative deacetylation pathway. In contrast, in submerged culture, it decreased 3.15-fold at the end of the biotransformation compared with the initial content, showing a low energetic state, while the NAD⁺/NADH ratio (23.15) increased 1.81-fold. It seems that in submerged culture, low energetic and high oxidative states are the physiological conditions that can redirect the ferulic catabolism into β-oxidative pathway and/or vanillin oxidation to produce vanillic acid.

Indicator dye based screening of glutaminase free L-asparaginase producer and kinetic evaluation of enzyme production process

Several soil isolates from 1 g of soil sample were isolated and screened for the production of L-asparaginase. Primary screening was performed using rapid plate assay; dye indicator studies were conducted, and phenol red with 0.005% concentration was found to be optimum. The secondary screening was carried out using the Nesslerization method. The bacteria screened for L-asparaginase production with no glutaminase activity was identified as Bacillus subtilis. Crude L-asparaginase enzyme was partially purified 1.57 folds of purity and 110 U/mg of specific activity. The glutaminase-free L-asparaginase activity was also confirmed using LC-MS analysis. The presence of mass peaks at 147.0 in the reaction mixture suggested an absence of glutaminase activity. An optimized medium obtained comprised of Dextrose 1.5 g/L, K₂HPO₄ 1.2 g/L, L-asparagine 15 g/L, and Tryptone 5 g/L. The highest L-asparaginase activity was observed at 6.0 pH and 30 °C. Kinetic parameters associated with biomass and L-asparaginase production were also studied. The computed values were µ_m 0.104 h^-1, X_m 6g/L P₀ 1.7U/mL P_m 8.2 U/mL Y_X/S 4 g-cell/g-glucose µP_m 0.35 h^-1 q_p 5.46 U/g/h Y_P/x 13.6667 U/g-cell. The novel bacterial isolates showed promise as a potential glutaminase-free L-asparaginase producer, which can prove to be of industrial applications.

Enhancement of Bacillus subtilis Growth and Sporulation by Two-Stage Solid-State Fermentation Strategy

Two-stage solid-state fermentation strategy was exploited and systematically optimized to enhance Bacillus subtilis growth and sporulation for increasing effective cell number in B. subtilis microbial ecological agents. The first stage focused on improving cell growth followed by the second stage aiming to enhance both cell growth and sporulation. The optimal fermentation condition was that temperature changed from 37 °C to 47 °C at a fermentation time of 48 h and Mn2+ content in medium was 4.9 mg MnSO4/g dry medium. Solid medium properties were improved by the optimal two-stage fermentation. HPLC results demonstrated that glucose utilization was facilitated and low-field nuclear magnetic resonance (LF-NMR) results showed that more active sites in medium for microbial cells were generated during the optimal two-stage fermentation. Moreover, microbial growth and sporulation were enhanced simultaneously during the second stage of fermentation through delaying microbial decline phase and increasing sporulation rate. As a result, effective cell number of B. subtilis reached 1.79 × 1010/g dry medium after fermentation for 72 h, which was 29.7% and 8.48% higher than that of conventional fermentation for 72 h and 48 h, respectively. Therefore, the optimal two-stage fermentation could increase the effective cell number of B. subtilis microbial ecological agents efficiently.