Cell-free Fermentation Broth Research Articles

Optimization of fermentation temperature and time for production of an antifungal extract from Bacillus amyloliquefaciens B17

Background/Objective. Species of Bacillus are currently gaining interest because its ability to produce secondary metabolites with antifungal properties against various plant pathogenic fungi. The objective of this study was to optimize fermentation temperature and time for antifungal extract production by Bacillus amyloliquefaciens B17 and to verify its activity against plant pathogenic fungi Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea. Materials and Methods. A central composite design (CCD) with two factors and five levels (fermentation temperature: 23.7, 25, 28, 31, and 32.2 °C and fermentation time: 25, 46, 95, 144, and 164. 3 h) was used. Thirteen combinations of temperature and fermentation time were randomly performed. The thirteen crude extracts of B. amyloliquefaciens B17 were obtained from the cell-free fermentation broth by acid precipitation followed by alkaline solubilization. The response variable was the diameter of the inhibition halos generated by placing drops of the different crude extracts onto the medium already inoculated with a suspension of Gilbertella persicaria spores. Results. The optimal conditions for the production of the extract with the greatest antifungal activity in B. amyloliquefaciens B17 were 26.8 °C and 158.6 h. Conclusion. The optimized crude extract from B. amyloliquefaciens B17 exhibited a strong ability to inhibit mycelial growth and spore germination of Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea.

Development and Comparison of Alternative Methods for the Purification of Adalimumab Directly from Harvested Cell Culture Fluid.

Protein A affinity chromatography is a well-established method currently used in the pharmaceutical industry. However, the high costs usually associated with chromatographic separation of protein A and the difficulties in continuous operation make the investigation of alternative purification methods very important. In this study, extraction/back-extraction and precipitation/dissolution methods were developed and optimised. They were compared with protein A and cation exchange chromatography separations in terms of yield of monoclonal antibody (mAb) and amount of residual impurities, such as DNA and host cell proteins, and amount of mAb aggregates. For a comprehensive comparison of the different methods, experiments were carried out with the same cell-free fermentation broth containing adalimumab. Protein A and cation exchange chromatographic separations resulted in high yield and purity of adalimumab. The precipitation-based process resulted in high yield but with lower purity. The extraction-based purification resulted in low yield and purity. Thus, the precipitation-based method proved to be more promising than the extraction-based method for direct purification of adalimumab from harvested cell culture fluid. Although alternative purification methods may offer the advantages of simplicity and low-cost operation, further significant improvements are required to compete with the performance of chromatographic separations of adalimumab from true fermentation broth.

Whole-genome analysis and secondary metabolites production of a new strain Brevibacillus halotolerans 7WMA2: A potential biocontrol agent against fungal pathogens

The extensive usage of synthetic fungicides against fungal diseases has caused adverse impacts on both human and agricultural crops. Therefore, the current study aims to establish a new bacterium 7WMA2, as a biocontrol agent to achieve better antifungal results. The strain 7WMA2 was isolated from marine sediment, displayed a broad spectrum of several fungi that includes Alternaria alternata, Cladosporium sp., Candida albicans, Fusarium oxysporum, Trichosporon pullulans, and Trichophyton rubrum. The 16S rRNA phylogeny inferred that strain 7WMA2 was a member of Brevibacillus. The phylogenetic and biochemical analyses revealed that the strain 7WMA2 belongs to the species of Brevibacillus halotolerans. The complete genome sequence of Brevibacillus halotolerans 7WMA2 consists of a circular chromosome of 5,351,077 bp length with a GC content of 41.39 mol %, including 4433 CDS, 111 tRNA genes, and 36 rRNA genes. The genomic analysis showed 23 putative biosynthetic secondary metabolite gene clusters responsible for non-ribosomal peptides, polyketides and siderophores. The antifungal compounds concentrated from cell-free fermentation broth demonstrated strong inhibition of fungi, and the compounds are considerably thermal stable and adaptable to pH range 2–12. This complete genome sequence has provided insight for further exploration of antagonistic ability and its secondary metabolite compounds indicated feasibility as biological control agents against fungal infections.

Bacterial Community Composition in the Growth Process of Pleurotus eryngii and Growth-Promoting Abilities of Isolated Bacteria.

The effects of biological factors on the vegetative growth process of mushrooms remain largely unexplored. We investigated the bacterial community in different growth stages of Pleurotus eryngii by high-throughput sequencing technology to explore the relationship between interacting bacteria and the growth and development of P. eryngii. We found significant variances in mushroom interacting association bacteria (MIAB) compositions among the samples from different growth stages, and 410 genera were identified. The bacteria in the full-bag and post-ripe stages were shifted to the biocontrol and growth-promotion ones. The mushroom growth-promoting bacteria (MGPB) were also isolated successfully and identified as B. cereus Bac1. The growth speed and density of mycelial pellets of P. eryngii, and activities of two exoenzymes (laccase and amylase), were analyzed by adding the different volumes of cell-free fermentation broth of B. cereus Bac1 to fungal culture media. The results showed that when a 5 mL cell-free fermentation broth was used, the growth speed of P. eryngii hyphae was enhanced by 1.15-fold over the control and reached 0.46 mm/h. The relative activity of laccase and amylase was increased by 26.9 and 43.83%. Our study revealed that the abundant interacting bacteria coexist with P. eryngii hyphae. Moreover, the abundance of some bacteria exhibiting a positive correlation with the growth periods of their host fungi can effectively promote the growth of the host, which will provide technical supports on the high-efficiency production of P. eryngii in factory cultivation.

Encapsulation and Algicidal Properties of Fermentation Products From Vibrio brasiliensis H115

Algicidal bacteria offer an eco-friendly and promising approach for controlling harmful algae blooms (HABs). In this study, repeated batch fermentation of immobilized algicidal bacterium Vibrio brasiliensis H115 was preformed to enhance the productivity of the algicidal compounds. The highest algicidal efficiency of the fermentation products against Akashiwo sanguinea (100%) was achieved when the fermentation time was decreased from 24 to 14 h. The cell-free fermentation broth was then spray-dried and floating microcapsules were prepared from the dried powder. The optimum preparation conditions for floating microcapsules were: sodium alginate (SA), 3%; CaCO3: SA (mass ratio), 3:4; CaCl2, 3%; citric acid, 4%; ethylcellulose, 2%; crosslinking time, 30 min. Under the optimal conditions, the floating microcapsules displayed efficient A. sanguinea cell lysis ability and the algicidal efficiency increased from 10.62% (4 h) to 100% (24 h). These results suggest that the floating microcapsules could potentially be practically used for controlling the outbreaks of A. sanguinea.

Cell-Free Fermentation Broth of Bacillus velezensis Strain S3-1 Improves Pak Choi Nutritional Quality and Changes the Bacterial Community Structure of the Rhizosphere Soil.

Bacillus velezensis is a plant growth-promoting rhizobacteria (PGPR) that has long been proven to improve the growth of plants, and it has been widely used in agriculture. However, in many reports, we observed that during the application of bacterial fluids, it appeared that the effect of the cell-free fermentation broth (CFB) was ignored. The purpose of this study is to compare the effect of the no inoculation treatment (CK), the B. velezensis strain S3-1 treatment (S), the CFB treatment in the Pak choi, soil bacterial community structure, soil enzyme activity, and field soil properties. The results have shown that, compared to the inoculation B. velezensis strain S3-1 treatment and the no-inoculation treatment; the inoculation of the CFB treatment can significantly enhance the soluble protein, soluble solids, ascorbic acid of Pak choi and increase the total phosphorus content and electrical conductivity (EC) in the soil. Based on high-throughput sequencing data, our analysis of soil microbial communities used R, NETWORK, and PICRUSt showed that the CFB treatment can enhance the relative abundance of Acidobacteria in the soil, decrease the abundance of native Bacillus in the soil, change the microbial community structure of the top 50 operational taxonomic units (OTUs), and improve soil microbial carbon metabolism and nitrogen metabolism. Overall, we observed that CFB treatment can also improve plant nutrition and change soil microbial communities. This study provides new insights for the application of microbial fertilizers in agricultural production.

Effect of zymomonas mobilis probiotic on cholesterol and its lipoprotein fractions and the intestinal regulation.

Zymomonas mobilis have characteristics that classify it as probiotic. Thus, this study aimed to evaluate the effect of regular consumption of fermented broth of this strain on the intestinal function of individuals with changes in intestinal transit. This is a randomized, descriptive and quantitative clinical trial, a sample composed of undergraduate students from a university center in Caruaru. After screening for individuals with constipation according to the inclusion and exclusion criteria, only 13 agreed to participate in the study. They were divided into groups: group 1 received Zymomonas mobilis fermented broth once a day; group 2 also received the fermented broth in the same concentration cells being twice a day; group 3 received cell-free fermented broth once daily; and group 4, placebo, received saline once daily, all groups drank for fifteen days, and laboratory tests were performed to check lipid profile before and after that period. Observed an increase in evacuation days in all groups averaged in media 7.0-10.5 days. Groups 1 and 2 showed an increase in total cholesterol (0.5% and 5.0%, respectively), HDL cholesterol (4.1% and 24.1%), LDL cholesterol (4.9% and 8.4%), VLDL cholesterol (17.9% and 11.2%) and triglycerides (19.1% and 27.9%). In group 3, there was a reduction of total cholesterol (-2.4%), LDL cholesterol (-11.2%), VLDL cholesterol (-15.9%), triglycerides (-27.7%) and increase in HDL cholesterol (25.7%). Thus, the broth fermented with Zymomonas mobilis regulated the intestinal transit, but did not improve the lipid profile, while the without cells broth showed a better lipid profile.

Mixed bacterial fermentation can control the growth and development of Verticillium dahliae

Verticillium wilt is a severe disease caused by Verticillium dahliae, which afflicts many crops, particularly cotton in the Xinjiang province of China. Chemical fungicides are harmful to the environment, and biological control agents against the fungal pathogens of plants provide an alternative to chemicals. Biological control agents include antagonistic bacteria or metabolic products. We investigated the inhibitory effects of two plant-growth-promoting rhizobacterial (PGPR) strains, namely Bacillus tequilensis C-9 and Sphingobacterium A1, against V. dahliae in vitro and in the field. We used the mixed fermentation of two bacteria to inhibit V. dahliae. Antimicrobial assays were performed and showed that spore production and germination, and the virulence protein of V. dahliae were reduced after treatment with cell-free mixed fermentation broth. In field studies, there was improvement in the disease severity, along with declined incidence and index after the treatment in the bud and bell stages. To explore the molecular mechanisms of this inhibition, we studied six metabolism-related genes by real-time quantitative polymerase chain reaction (qRT-PCR). The results showed that in response to mixed fermentation broth, some genes related to growth and development were significantly upregulated, explaining the structural changes observed in V. dahliae. Some genes that regulate oxidative stress were also dramatically induced, indicating that mixed bacterial fermentation had a significant impact on V. dahliae. These results support the idea that the cell-free mixed fermentation broth of Bacillus tequilensis C-9 and Sphingobacterium A1, when applied for biocontrols, can inhibit V. dahliae in vitro and in vivo.

Effect of sugar cane molasses and tofu waste on the inhibitory activity of cell free fermentation broth of streptomyces antibioticus K-6

The use of waste as source of nutrition for human, animals, plants, and microorganism has been reported. The aim of this study was to observe the influence of sugar cane molasses (SCM) and tofu waste (TW) in various concentrations on the inhibitory effect of cell free fermentation broth (CFFB) of Streptomyces antibioticus K-6 isolated from plantation soil compare to International Streptomyces Project (ISP) standard media. The fermentation was performed in 150 rpm rotary shaker at 37ºC for five days. The inhibitory activity was investigated using diffusion agar on the nutrient agar media to determine ratio of  SCM and TW by which the largest growth inhibitory zone achieved. Escherichia coli ATCC 25922 was used as a test microorganism. 10% of Streptomyces antibioticus K-6 starter was inoculated into nine compositions  of  SCM, TW and its combination containing media. The result indicated that SCM and TWmight be used as the component of fermentation medium of Streptomyces antibioticus K-6 for producing active metabolites . The activity of  CFFB was exhibited as a diameter of growth  inhibitory zone  against the  test  bacteria; in which the largest value (24.4 mm) was detected in the combination of 0.5% SCM and 0.5% TW containig medium after  two days  incubation.

Different techniques for concentration of extracellular biopolymers with herbicidal activity produced by Phoma sp

ABSTRACT The natural ability of microorganisms to secrete high levels of bioactive compounds make them attractive hosts for producing novel compounds. Microbial biopolymers have potential applications in most of the sectors of the world economy. According to the physicochemical properties, they present some advantages, such as biodegradability, reproducibility, and stability. Based on this context, the objective of this work was to evaluate different methods for concentration and characterisation of extracellular biopolymers produced by Phoma sp. Extracellular biopolymers were produced by submerged fermentation and were concentrated by hollow fibre membranes and by adsorption. The structural characterisation of purified biopolymers was determined by Fourier Transform Infrared spectroscopy. Phytotoxic effects were assessed through absorption assays in detached leaves of Cucumis sativus and evaluated on the seventh day after application. The surface tension was evaluated for each sample. Hollow-fibre microfiltration membrane presented a higher purification factor than hollow-fibre ultrafiltration membrane. Extracellular biopolymers were identified in the permeate and retentate fractions, but in higher concentration in the retentate fractions. The adsorption process was efficient for recovering more than 88% of extracellular biopolymers from cell-free fermented broth. The best performance was obtained by using silica and activated carbon as adsorbent, with a recovery higher than 93%. The herbicidal activity was proportional to the concentration of biopolymers and the results are very promising for future applications because a concentrated solution of biopolymers can increase weed control. Membrane processes can be used to develop a liquid formulation of bioherbicide, whereas adsorption can be used to develop a solid formula.

Two factor at a time approach by response surface methodology to aggrandize the Bacillus subtilis KLP2015 surfactin lipopeptide to use as antifungal agent

A Gram’s positive, rod shaped and endospores-forming ‘bacterial isolate KLP15′ was identified as Bacillus subtilis (Accession number KT459335) by the biochemical tests and 16S rRNA based sequencing. Lipopeptide(s) production from B. subtilis KLP2015 increased from 200.0 to 547.0 mg/l after the optimization of physico-chemical parameters like choice of nitrogen source, fermentation time, fermentation temperature and broth pH by ‘One Factor at a Time’ (OFAT) approach. Further, the yield of lipopeptide(s) increased to 985 mg/l from an earlier value of 547 mg/l when a “Two Factors at a Time (TFAT) approach using Response Surface Methodology (RSM) was attempted. The extracted crude lipopeptide fraction from the cell-free fermentation broth of B. subtilis KLP2015 was purified and characterized by High Performance Liquid Chromatography (HPLC), Thin Layer Chromatography (TLC), UV-Visible Spectrophotometry (UV-vis), Fourier Transform Infrared (FTIR) and MALDI-TOF studies. HPLC and TLC results confirmed the purity of the lipopeptide preparation and its Surfactin-type nature. The FTIR and MALDI-TOF spectra of the purified lipopeptide were found to be similar to that of an authentic Surfactin molecule. The purified lipopeptide showed potent 75.1% and 41.9% antifungal activity against Mucor sp. and Aspergillus niger, respectively on the basis of zone of inhibition of growth of these fungal strains. Moreover, the purified lipopeptide preparation of B. subtilis KLP2015 was most effective against the growth of Mucor sp. as reflected by the recorded MIC values of 6.25 µg/ml while MIC of lipopeptide for the A. niger was 12.5 µg/ml.

Development of a novel bio-organic fertilizer for plant growth promotion and suppression of rhizome rot in ginger

Rhizome rot of ginger caused by Fusarium oxysporum f. sp. zingiberi (Foz) is a soil-borne disease that adversely affects the seed rhizomes and crop production. Bacillus amyloliquefaciens NJPRHSDAQ-1 (NP-1), which has a substantial inhibitory effect on Foz in vitro, was isolated from the ginger rhizosphere. A pot experiment indicated that a bio-organic fertilizer made from NP-1 (BIO2) or other universal biocontrol agents (BIO1), the suspension of NP-1 (NP-1), and its cell-free fermentation broth (NP-1fb), all effectively reduced the disease incidence of rhizome rot, stimulated plant growth, and improved the microbial community compared to the control. The best control effect (78.3%) and the most significant suppression of Foz abundance (75.8% compared to control) were all observed in the BIO2 treatment. Two field experiments further indicated that BIO2 amendment can significantly increase ginger yield by 8.0–11.5% and can decrease the Foz population by 30.8–51.0% compared to control plants receiving only chemical fertilizer. Application of BIO2 also increased the growth and nutrient quality of ginger and soil enzyme activity. Pearson correlation analysis indicated a significant negative relationship between the abundance of culturable bacteria and Foz, while a negative correlation between culturable actinomycetes/fungi population and invertase/urease activity was observed. This study highlights the application prospect of a novel bio-organic fertilizer in ginger production for both disease suppression and growth promotion.

Enhanced effectiveness of Rhizopus oryzae by immobilization in a static bed fermentor for l -lactic acid production

Abstract The static bed fermentor was successfully employed for cell immobilization in this study. By complete immobilization of Rhizopus oryzae on a fibrous matrix, cell-free fermentation broth resulted in improved mass transfer and easy operation compared with free cell fermentation in a typical stirred fermentor. Environmental conditions generated in this fermentor configuration favoring the immobilized R. oryzae to grow and produce lactic acid without substrate repression at high initial glucose concentration during batch cultivation. Approximately 67% of the theoretical lactate yield (0.50 g/g) with the productivity of 1.05 g/L h and the final titer of 75.28 g/L was obtained from fermentation with high glucose concentration (150 g/L). Complete cell immobilization supported the continuous operation of lactic acid production by R. oryzae since cell wash out was diminished. When operating the continuous culture at an appropriate dilution rate, a sufficiently high concentration of lactic acid (72.32 g/L) with a small amount of remaining glucose (

New extracellular thermostable oxalate oxidase produced from endophytic Ochrobactrum intermedium CL6: Purification and biochemical characterization

ABSTRACTOxalate oxidase (EC 1.2.3.4) catalyzes the oxidative cleavage of oxalate to carbon dioxide with the reduction of molecular oxygen to hydrogen peroxide. Oxalate oxidase found its application in clinical assay for oxalate in blood and urine. This study describes the purification and biochemical characterization of an oxalate oxidase produced from an endophytic bacterium, Ochrobactrum intermedium CL6. The cell-free fermentation broth was subjected to two-step enzyme purification, which resulted in a 58.74-fold purification with 83% recovery. Specific activity of the final purified enzyme was 26.78 U mg−1 protein. The enzyme displayed an optimum pH and temperature of 3.8 and 80°C, respectively, and high stability at 4–80°C for 6 h. The enzymatic activity was not influenced by metal ions and chemical agents (K+, Na+, Zn2+, Fe3+, Mn2+, Mg2+, glucose, urea, lactate) commonly found in serum and urine, with Cu2+ being the exception. The enzyme appears to be a metalloprotein stimulated by Ca2+ and Fe2+. Its Km and Kcat for oxalate were found to be 0.45 mM and 85 s−1, respectively. This enzyme is the only known oxalate oxidase which did not show substrate inhibition up to a substrate concentration of 50 mM. Thermostability, kinetic properties, and the absence of substrate inhibition make this enzyme an ideal candidate for clinical applications.

Design of aqueous two-phase systems for purification of hyaluronic acid produced by metabolically engineered Lactococcus lactis.

Hyaluronic acid has a wide range of biomedical applications and its commercial value is highly dependent on its purity and molecular weight. This study highlights the utility of aqueous two-phase separation as a primary recovery step for hyaluronic acid and for removal of major protein impurities from fermentation broths. Metabolically engineered cultures of a lactate dehydrogenase mutant strain of Lactococcus lactis (L. lactis NZ9020) were used to produce high-molecular-weight hyaluronic acid. The cell-free fermentation broth was partially purified using a polyethylene glycol/potassium phosphate system, resulting in nearly 100% recovery of hyaluronic acid in the salt-rich bottom phase in all the aqueous two-phase separation experiments. These experiments were optimized for maximum removal of protein impurities in the polyethylene glycol rich top phase. The removal of protein impurities resulted in substantial reduction of membrane fouling in the subsequent diafiltration process, carried out with a 300 kDa polyether sulfone membrane. This step resulted in considerable purification of hyaluronic acid, without any loss in recovery and molecular weight. Diafiltration was followed by an adsorption step to remove minor impurities and achieve nearly 100% purity. The final hyaluronic acid product was characterized by Fourier-transform IR and NMR spectroscopy, confirming its purity.

Inhibition Of In Vitro Growth Of Porcine Enterotoxigenic And Shiga Toxin-Producing Escherichia Coli By Lactobacillus Plantarum Strains

Abstract The objective of this study was to assess cell-free fermented culture broth of 9 Lactobacillus plantarum strains as antibiotic alternatives for the inhibition of in vitro growth of enterotoxigenic Escherichia coli (ETEC) and Shiga toxin-producing E. coli (STEC) isolated from postweaning pigs with colibacillosis and edema disease in 2014. A total of 10 ETEC and 5 STEC strains isolated from postweaning pigs were tested in antimicrobial susceptibility tests. ETEC and STEC strains used in this study possessed at least one of fimbrial, enterotoxin, and Shiga-toxin genes when tested by polymerase chain reaction. Among 9 L. plantarum strains tested, 3 strains (Lp 2-05, 2-06, and 1-03) showed inhibitory activity of in vitro growth against 10 ETEC strains (100%) and 7 strains (Lp 6-13, 3-06, 3-05, 7-01, 2-06, 1-03, and 6-05) showed inhibitory activity of in vitro growth against 5 STEC strains (100%). Three strains (Lp 3-05, 2-06, and 1-03) showed inhibitory activity of in vitro growth against 10 ETEC (100%) and 5 STEC (100%) strains. The results of this study show the inhibitory activity of cell-free fermented culture broth of L. plantarum against ETEC and STEC isolated from postweaning pigs with colibacillosis and edema disease.

Partitioning of β-galactosidase in aqueous two-phase systems containing polyethyleneglycol and phosphate salts

Purification of a desired protein from fermentation broth containing a wide variety of biomolecules is one of the major challenges in the biotechnology industry. One possible strategy for this challenge, an aqueous two-phase extraction (APTE) can be used as the primary downstream processing for partial purification of industrial enzymes. In the present study, the feasibility of utilizing ATPE for the partitioning behavior of β-galactosidase (from Aspergilus niger) was investigated. The results showed that the PEG2000/(NH4)2HPO4 system was suitable for the extraction of β-galactosidase from cell free fermentation broth of A. niger PTCC 1050. In the following, multilevel factorial design was used to evaluate the effects of three independent variables (PEG to salt weight ratio, fermentation broth loaded mass and system pH) on β-galactosidase extraction. The results indicated that PEG to salt weight ratio and fermentation broth loaded mass was the major contributory factors for β-galactosidase partitioning. Among the different conditions studied, a phase system having a composition of 15.24% (w/w) PEG2000 and 17.14% (w/w) (NH4)2HPO4 at pH 7 with loaded fermentation broth of 5% (w/w) gave the best overall results in term of purification degree.

Identification and characterization of novel surfactins produced by fungal antagonist Bacillus amyloliquefaciens 6B

The broad-spectrum fungal antagonist, Bacillus amyloliquefaciens 6B (BA6B), isolated from the Jakhao coast of Kutch, India, was investigated for its antifungal metabolites using mass spectrometry. The cyclic lipopeptides harvested from the cell-free fermentation broth of BA6B by acid precipitation and subsequently dissolved in methanol were subjected to liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS/MS) for their identification and sequence determination. The 26 types of surfactin variants were identified from the methanolic extract by LC-ESI-MS/MS analysis. Among 26 surfactin species, several new cyclic as well as acyclic surfactin variants based on the variation in the β-hydroxy fatty acid (β-OH FA) chain length and/or in amino acid positions 4, 5, 6, and 7 were identified. The mass spectrometric analysis of crude extract also enabled the identification of 11 unique molecular mass ions with minimum two or maximum four types of isobaric peptide variants.

Crude glycerol from biodiesel industry as substrate for biosurfactant production by Bacillus subtilis ATCC 6633

Glycerol, a co-product of the biodiesel industry, may be a suitable raw material for the production of high added-value compounds by the microorganisms. This study aimed to use the glycerol obtained from the biodiesel production process as the main carbon source for biosurfactant production by Bacillus subtilis ATCC 6633. Results indicated that the strain lowered the surface tension of the cell-free fermented broth to 31.5 ± 1.6 mN/m, indicating the production of biosurfactant. The critical micelle concentration (CMC = 33.6 mN/m) obtained was similar to the previously reported for biossurfactants isolated from other Bacillus. The produced biosurfactant was able to emulsify n-hexadecane and soybean oil.

2,3-Butanediol recovery from fermentation broth by alcohol precipitation and vacuum distillation

This study presents a new and effective downstream process to recover 2,3-butanediol (2,3-BD) from fermentation broth which is produced by a recombinant Klebsiella pneumoniae strain. The ldhA-deficient K. pneumoniae strain yielded about 90 g/L of 2,3-BD, along with a number of by-products, such as organic acids and alcohols, in a 65 h fed-batch fermentation. The pH-adjusted cell-free fermentation broth was firstly concentrated until 2,3-BD reached around 500 g/L by vacuum evaporation at 50°C and 50 mbar vacuum pressure. The concentrated solution was further treated using light alcohols, including methanol, ethanol, and isopropanol, for the precipitation of organic acids and inorganic salts. Isopropanol showed the highest removal efficiency, in which 92.5% and 99.8% of organic acids and inorganic salts were precipitated, respectively. At a final step, a vacuum distillation process enabled the recovery of 76.2% of the treated 2,3-BD, with 96.1% purity, indicating that fermentatively produced 2,3-BD is effectively recovered by a simple alcohol precipitation and vacuum distillation.