Measurement of the change in aerosol size distribution with bacterial growth in a pilot scale fermentor

A number of industrial processes require the addition of materials to the fermentation broth that are hazardous to health and environment. Agitation of broths inoculated with microorganisms can potentially release aerosols large enough to carry the microorganisms. The influence of agitation, air flow, and bacterial growth on aerosol size distribution, air flow, and bacterial growth on aerosol size distribution was investigated in an industrial pilot scale fermentor. A decrease in particle concentration was observed with increase in bacterial growth; this change was more pronounced in the size range above 2 mum. The aerosol size distribution was found to be practically independent of air flow rate and agitation rate for sizes less than 2 mum. However, for particles largar than 2 mum, the concentration was found to increase with an increase in air flow rate and agitation rate.     

A minicomputer system for analyzing and reporting pilot plant fermentor data

In 1979, a minicomputer system was developed for Hoffmann-La Roche by ABEC, Inc. for the purpose of achieving on-line analysis and reporting of data from 16 70-L pilot-plant fermentors (New Brunswick Scientific Co.). The system consists of a PDP 11/60 computer with 96K core capacity, two RL01 disk drives, two RX01 floppy-disk drives, LA-36 DECwriter terminal, Tektronix CRT, and Versatec printer plotter. DEC, PDP, RSX, RL01, RX01, LA-36, and DECwriter are trademarks of Digital Equipment Corporation. The computer software comprises three distinct groups of programs. RSX-11M is a disk-based operating system that allows quick response to realtime events, such as process monitoring and data acquisition, while carrying out less time-dependent activities, such as program development and graphical output. The AIM (Biles, Inc.) system is used to acquire and convert the voltage signals produced by pilot-plant instrumentation into engineering units. Analysis and graphical output are executed by ABEC and Versatec supplied programs. The most beneficial task performed by the computer is the production of graphical output of a variety of measured and analyzed data. This has led to an increase in personnel productivity and design of more meaningful experiments. An ancillary function of the system is to pick up data logged by a PDP 11/03 computer from a remote fermentation production plant by means of a MODEM interfaced communication link. Production data are analyzed and presented in a form identical with pilot-plant data. The experience with the system is discussed in this article.     

Studies on Brevibacterium linens metabolism in fermentor

Summary Growth and metabolism of Brevibacterium linens were studied in a fermentor regulated for fixed levels of pH (7.5 to 8.5), temperature (20–30° C) and dissolved oxygen (40%–60% of air saturated medium). The curves of disappearance of l-lactate and amino acids were invariable, indicating that phenylalanine, tyrosine, arginine, proline, glutamic acid and histidine are growth-limiting nutrients. Ornithine appeared at the beginning of cultures when oxygen consumption was low. Ammonia was produced, but large quantities were observed only when amino acid concentrations were higher than that of the carbon source. When the latter was low, the ammonia produced was consumed before a number of amino acids as an easily assimilable nitrogen source. Whether alkali or acid was consumed to maintain constant pH depended on the pH of the medium and on maximal growth rates.     

Lipase production of Staphylococcus carnosus in a dialysis fermentor

Summary In a newly constructed one-vessel dialysis fermentor, a strain of Staphylococcus carnosus TM300 carrying the lipase secretion plasmid pLipPS1 was used to investigate exoenzyme and biomass production. The bacterial culture grows in an inner compartment of 21 volume, separated from a 101 nutrient broth compartment by a conventional dialysis membrane. In order to avoid substrate depletion and to prolong the growth phase, a highly concentrated nutrient broth was used. The biomass production reached 60 g cell dry weight/l. The increase in extracellular lipase concentration was directly coupled with the increase of cell mass and reached a value of 230 mg/l culture supernatant. Harvesting the cells in the late growth phase, the lipase content was about 30% of the total exoproteins in the supernatant.     

Bioethanol production from the hydrolysate of rape stem in a surface-aerated fermentor

In this study, we investigated the feasibility of producing bioethanol from the hydrolysate of rape stem. Specifically, the most ideal yeast strain was screened, and the microaeration was performed by surface aeration on a liquid medium surface. Among the yeast strains examined, Pichia stipitis CBS 7126 displayed the best performance in bioethanol production during the surface-aerated fermentor culture. Pichia stipitis CBS 7126 produced maximally 9.56 g/l of bioethanol from the initial total reducing sugars (about 28 g/l). The bioethanol yield was 0.397 (by the DNS method). Furthermore, this controlled surface aeration method holds promise for use in the bioethanol production from the xylose-containing lignocellulosic hydrolysate of biomass.     

Pilot plant fermentation of Streptomyces nigrificans in a mechanically agitated fermentor

Summary Optimal conditions for Streptomyces nigrificans growth, yields of glucose isomerase and protease activity were tested during fermentations in a mechanically agitated pilot plant fermentor, at two different impeller rotational speeds.     

The production of mycobacterial antigens by homogeneous culture in a fermentor

Mycobacterium bovis strain BCG, substrain 1173P2, has been grown in homogeneous culture in classical synthetic Sauton medium without supplementary ingredients. The culture conditions are described. The protein release in the culture medium and the tuberculin yield after 2% trichloroacetic acid precipitation were significantly improved. The antigenicity of the tuberculin has been successfully assayed on specifically sensitized guinea-pigs. It is concluded that homogeneous mycobacterium culture in a fermentor using synthetic medium is a suitable method for the large scale production of antigen.     

Optimization of the spray drying of a Paenibacillus polymyxa-based biopesticide on pilot plant and production scales

Spore survival and moisture content are two important properties of biopesticides, and both are related to field biocontrol efficacy and storage shelf life. In this study, Paenibacillus polymyxa (HY96-2) was spray-dried on both pilot plant and production scales, and the effects of inlet and outlet temperatures on spore survival and moisture content were investigated. The results showed that inlet temperatures ranging from 170 to 230 °C (at an outlet temperature of 80 °C) had no obvious effect on the two properties during pilot scale processing, although an inlet temperature of 230 °C resulted in higher feed speed. When the outlet temperature on the pilot scale was reduced from 100 to 80 °C, no obvious variations in spore survival and moisture content were found, while a further reduction from 80 to 65 °C resulted in a decline in spore survival from 81.0 to 67.0% and an increase in moisture content from 2.3 to 31.7%. These results indicate that both outlet temperature and moisture content have an effect on spore survival. Optimum inlet and outlet temperatures for P. polymyxa processing were 230 °C and 85–90 °C on a production scale. Under these conditions, spore survival and moisture content were 83.5–86.6% and 2.73––4.12%, respectively.     

Bench-top fermentative production of plant benzylisoquinoline alkaloids using a bacterial platform

The plant secondary metabolites benzylisoquinoline alkaloids (BIAs) have diverse pharmaceutical activities, and some are used medicinally (e.g., morphine, codeine, berberine). Recently, we constructed a platform to produce BIAs using bioengineered Escherichia coli, which could be useful for bulk production. The E. coli strain used in this system produces the important intermediate (S)-reticuline from glucose or glycerol. Although the amount produced (40 mg/L) exceeded the amount that can be purified from plants, the conversion efficiency from glycerol was only 0.15%; thus, there was much room for improvement. Our production system was developed in a jar fermenter but it is difficult to work with multiple samples using this system. In contrast, many samples can be cultured in parallel using shake flask cultures, allowing optimization of production conditions. Here, we describe bench-top production of (S)-reticuline and optimization of culture conditions using shake flask cultures. The production of (S)-reticuline reached 33.9 mg/L.     

Ethanol production in a microporous hollow-fiber-based extractive fermentor with immobilized yeast

Microporous-membrane-based extractive product recovery in product-inhibited fermentations allows in situ recovery of inhibitory products in a nondispersive fashion. A tubular bioreactor with continuous strands of hydrophobic microporous hollow fibers having extracting solvent flowing in fiber lumen was utilized for yeast fermentation of glucose to ethanol. Yeast was effectively immobilized on the shell side in small lengths of chopped microporous hyrophilic hollow fibers. The beneficial effects of in situ dispersion-free solvent ex (oleyl alcohol and dibutyl phthalate) were demonstrated for a 300 g/L glucose substrate feed. Outlet glucose concentration dropped drastically from 123 to 41 g/L as solvent/ substrate flow ratio was increased from 0 to 3 at 9 mL/h of substrate flow rate with oleyl alcohol as extracting solvent. The significant productivity increase with in situ solvent extraction became more evident as solvent/ substrate flow ratio increased. A model of the locally integrated extractive bioreactor describes the observed fermentor performance quite well.     

Continuous production of extracellular protease by Bacillus subtilis in a two-stage fermentor

Growth and protease production of Bacillus subtilis in semisynthetic and synthetic media were studied in batch culture and in a two-stage, laboratory scale, continuous fermentor. The amount, of extracellular protease production was measured under specific growth conditions in both stages of the ferment or. At the dilution rates employed, the cells in the first stage of the ferment or produced negligible quantities of protease, and the culture primarily functioned as a continuous inoculum for the second stage of the fermentor. The culture effluent from the second stage of the fermentor contained extracellular protease, on the average, equal to 60 per cent, of the activity that had been found in the supernatant of a 48-hr batch culture grown in a medium having the same composition as that in the continuous fermentor. Extracellular protease was produced in semisynthetic medium by B. subtilis in the two-stage fermentor for as long as 20 days without culture degeneration. Additional studies indicated that continuous protease production could also be achieved in a synthetic medium. The RNA/ protein ratios of cells grown in semisynthetic medium in batch culture and in each stage of the two-stage fermentor were examined. There was a positive correlation between the amount of protease produced by the cells and their RNA/ protein ratio. Techniques employed for continuous production of protease by B. subtilis and the potential use of the method for investigating the control of secondary metabolite synthesis are discussed.     

Optimization of L-malic acid production by Aspergillus flavus in a stirred fermentor

Effects of various nutritional and environmental factors on the accumulation of organic acids (mainly L-malic acid) by the filamentous fungus Aspergillus flavus were studied in a 16-L stirred fermentor. Improvement of the molar yield (moles acid produced per moles glucose consumed) of L-malic acid was obtained mainly by increasing the agitation rate (to 350 rpm) and the Fe(z+) ion concentration (to 12 mg/L) and by lowering the nitrogen (to 271 mg/L) and phosphate concentrations (to 1.5 mM) in the medium. These changes resulted in molar yields for L-malic acid and total C(4) acids (L-malic, succinic, and fumaric acids) of 128 and 155%, respectively. The high molar yields obtained (above 100%) are additional evidence for the operation of part of the reductive branch of the tricarboxylic acid cycle in L-malic acid accumulation by A. flavus. The fermentation conditions developed using the above mentioned factors and 9% CaCO(3) in the medium resulted in a high concentration (113 g/L L-malic acid from 120 g/L glucose utilized) and a high overall productivity (0.59 g/L h) of L-malic acid. These changes in acid accumulation coincide with increases in the activities of NAD(+)-malate dehydrogenase, fumarase, and citrate synthase.     

Large scale production and semi-purification of kedarcidin in a 1000-L fermentor

Summary Actinomycete strain ATCC 53650 was grown in a 1000-L fermentor containing 680 L of medium and the production of kedarcidin was monitored by HPLC. The titers of kedarcidin in the fermentor cultures were 0.49–0.53 mg ml^–1. A quick and efficient purification method involving the use of anion exchange resin DE23 (batch adsorption-desorption) and an ultrafiltration system yielded high recovery (65% yield) of kedarcidin from the fermentor culture. Over 200 grams of lyophilized kedarcidin of 70% purity was recovered from each of two 1000-L fermentor cultures using this process.     

Ethanol production from sugar cane segments in a high solids drum fermentor

Summary A successful yeast fermentation for the production of relatively high concentration of ethanol (9% w/v) was carried out using sugar cane segments. Extraction of sugar from segments occurred simultaneously with ethanol formation. The beer produced was transferred to a fresh batch of sugar cane segments and the fermentation cycle was repeated successively three times with the same beer. A high cane to water ratio was obtained in a rotating drum fermentor which allowed for a minimal amount of liquid to be used during the fermentation process.     

Continuous production of ethanol by yeast "immobilized" in a membrane-contained fermentor

A dialysate-feed, immobilized-cell dialysis continuous fermentation system was investigated as a method of relieving product inhibition in the conversion of glucose to ethanol by cells of Saccharomyces cerevisiae ATCC 4126. The substrate was fed into a continuous dialysate circuit and then into a batch fermentor circuit via diffusion through the microporous membranes of an intermediate dialyzer. Simultaneously, product was withdrawn from the fermentor circuit through the dialyzer membranes into the dialysate circuit and out in the effluent. Since the fermentor was operated without an effluent, the cells essentially were immobilized and converted substrate to product by maintenance metabolism. Contrary to prior results with this novel system for the continuous fermentation of lactose to lactate by lactobacillus cells, a steady state of yeast cells in the fermentor did not occur initially but was obtained by the depletion of medium nitrogen and the prevention of cell breakage, although the substrate and product concentrations then became unsteady. The inherent advantages of the system was offset in the ethanol fermentation by relatively low productivity, which appeared to be limited by membrane permeability.