Production of curdlan-type polysaccharide by Alcaligenes faecalis in batch and continuous culture

1983 ◽  
Vol 29 (10) ◽  
pp. 1331-1338 ◽  
Author(s):  
K. Railton Phillips ◽  
J. Pik ◽  
H. G. Lawford ◽  
B. Lavers ◽  
A. Kligerman ◽  
...  
Keyword(s):  
Chemostat Culture ◽  
Product Yield ◽  
Alcaligenes Faecalis ◽  
Single Stage ◽  
Specific Rate ◽  
Continuous Cultures ◽  
Batch Cultures ◽  
Curdlan Production ◽  
Spontaneous Variant

The biosynthesis of a thermogelable, extracellular homo-β-(1 → 3)-glucan called "curdlan," has been studied in batch and continuous cultures of Alcaligenes faecalis var. myxogenes. Curdlan production is associated with the poststationary phase of a nitrogen-depleted, aerobic batch culture. Exopolymer is not detected in single-stage, carbon-limited continuous cultures but curdlan can be isolated from the effluent of a nitrogen-limited chemostat operating at a dilution rate (D) of < 0.1 h−1. A spontaneous variant of strain ATCC 21680 was isolated and found to be compatible with long-term, nitrogen-limited chemostat culture. The specific rate of curdlan production is approximately four times higher in poststationary batch cultures than in single-stage continuous fermentations. The product yield (Yp/s) associated with batch processing (nongrowing cultures) is approximately 0.5 g curdlan/g glucose, with CO2 being the only detectable by-product.

Theoretical maximum and observed product yields associated with curdlan production by Alcaligenes faecalis

1983 ◽  
Vol 29 (10) ◽  
pp. 1270-1276 ◽  
Author(s):  
K. R. Phillips ◽  
H. G. Lawford
Keyword(s):  
Process Improvement ◽  
Conversion Efficiency ◽  
Nitrogen Limitation ◽  
Glucose Consumption ◽  
Product Yield ◽  
Alcaligenes Faecalis ◽  
Carbon Limitation ◽  
Average Value ◽  
Theoretical Maximum ◽  
Curdlan Production

As a guide to both strain and process improvement and based on certain assumptions concerning both glucose and energy metabolism of the process organism, Alcaligenes faecalis var. myxogenes, the theoretical "maximum" carbon (glucose) substrate to product conversion efficiency (i.e., product yield) has been estimated for "curdlan-type" β(1 → 3)-glucan exopolysaccharide production in batch fermentations. Under nitrogen limitation, which promotes curdlan biosynthesis (μ = 0), the rate of glucose consumption for cellular maintenance energy (grams of glucose per gram of cells per hour) was approximately five times higher than under carbon limitation. The decrease in the theoretical "maximum" curdlan conversion efficiency of 74% to the average value of 50–56% was due primarily to the high maintenance coefficient of the nitrogen-starved culture.

scholarly journals Influence of Carbon Source on Nitrate Removal by Nitrate-TolerantKlebsiella oxytoca CECT 4460 in Batch and Chemostat Cultures

1998 ◽  
Vol 64 (8) ◽  
pp. 2970-2976 ◽  
Author(s):  
Guadalupe Piñar ◽  
Karin Kovárová ◽  
Thomas Egli ◽  
Juan L. Ramos
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Nitrate Removal ◽  
Dry Weight ◽  
Specific Rate ◽  
Continuous Cultures ◽  
Batch Cultures ◽  
Chemostat Cultures ◽  
C And N

ABSTRACT The nitrate-tolerant organism Klebsiella oxytoca CECT 4460 tolerates nitrate at concentrations up to 1 M and is used to treat wastewater with high nitrate loads in industrial wastewater treatment plants. We studied the influence of the C source (glycerol or sucrose or both) on the growth rate and the efficiency of nitrate removal under laboratory conditions. With sucrose as the sole C source the maximum specific growth rate was 0.3 h−1, whereas with glycerol it was 0.45 h−1. In batch cultures K. oxytocacells grown on sucrose or glycerol were able to immediately use sucrose as a sole C source, suggesting that sucrose uptake and metabolism were constitutive. In contrast, glycerol uptake occurred preferentially in glycerol-grown cells. Independent of the preculture conditions, when sucrose and glycerol were added simultaneously to batch cultures, the sucrose was used first, and once the supply of sucrose was exhausted, the glycerol was consumed. Utilization of nitrate as an N source occurred without nitrite or ammonium accumulation when glycerol was used, but nitrite accumulated when sucrose was used. In chemostat cultures K. oxytoca CECT 4460 efficiently removed nitrate without accumulation of nitrate or ammonium when sucrose, glycerol, or mixtures of these two C sources were used. The growth yields and the efficiencies of C and N utilization were determined at different growth rates in chemostat cultures. Regardless of the C source, yield carbon (YC) ranged between 1.3 and 1.0 g (dry weight) per g of sucrose C or glycerol C consumed. Regardless of the specific growth rate and the C source, yield nitrogen (YN) ranged from 17.2 to 12.5 g (dry weight) per g of nitrate N consumed. In contrast to batch cultures, in continuous cultures glycerol and sucrose were utilized simultaneously, although the specific rate of sucrose consumption was higher than the specific rate of glycerol consumption. In continuous cultures double-nutrient-limited growth appeared with respect to the C/N ratio of the feed medium and the dilution rate, so that for a C/N ratio between 10 and 30 and a growth rate of 0.1 h−1 the process led to simultaneous and efficient removal of the C and N sources used. At a growth rate of 0.2 h−1the zone of double limitation was between 8 and 11. This suggests that the regimen of double limitation is influenced by the C/N ratio and the growth rate. The results of these experiments were validated by pulse assays.

Nitrite reduction and methanogenesis in a single-stage UASB reactor

2015 ◽  
Vol 72 (12) ◽  
pp. 2236-2242 ◽  
Author(s):  
L. I. Borges ◽  
C. M. López-Vazquez ◽  
H. García ◽  
J. B. van Lier
Keyword(s):  
Domestic Wastewater ◽  
High Strength ◽  
Single Stage ◽  
Nitrite Reduction ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
N Removal

In this study, nitrite reduction and methanogenesis in a single-stage upflow anaerobic sludge blanket (UASB) reactor was investigated, using high-strength synthetic domestic wastewater as substrate. To assess long-term effects and evaluate the mechanisms that allow successful nitrite reduction and methanogenesis in a single-stage UASB, sludge was exposed to relatively high nitrite loading rates (315 ± 13 mgNO2−-N/(l.d)), using a chemical oxygen demand (COD) to nitrogen ratio of 18 gCOD/gNO2−-N, and an organic loading rate of 5.4 ± 0.2 gCOD/(l.d). In parallel, the effects of sludge morphology on methanogenesis inhibition were studied by performing short-term batch activity tests at different COD/NO2−-N ratios with anaerobic sludge samples. In long-term tests, denitrification was practically complete and COD removal efficiency did not change significantly after nitrite addition. Furthermore, methane production only decreased by 13%, agreeing with the reducing equivalents requirement for complete NO2− reduction to N2. Apparently, the spatial separation of denitrification and methanogenesis zones inside the UASB reactor allowed nitrite reduction and methanogenesis to occur at the same moment. Batch tests showed that granules seem to protect methanogens from nitrite inhibition, probably due to transport limitations. Combined COD and N removal via nitrite in a single-stage UASB reactor could be a feasible technology to treat high-strength domestic wastewater.

Exposure of Midline Cranial Base without a Facial Incision through a Combined Craniofacial-Transfacial Procedure

2005 ◽  
Vol 56 (suppl_1) ◽  
pp. ONS-28-ONS-35 ◽  
Author(s):  
Iman Feiz-Erfan ◽  
Patrick P. Han ◽  
Robert F. Spetzler ◽  
Randall W. Porter ◽  
Jeffrey D. Klopfenstein ◽  
...  
Keyword(s):  
Cranial Base ◽  
Single Stage ◽  
Karnofsky Performance Scale ◽  
Bony Defect ◽  
Anterior Cranial Base ◽  
Scale Scores ◽  
Long Term Follow Up ◽  
Cerebrospinal Fluid Leaks ◽  
Cosmetic Outcomes

Abstract OBJECTIVE: A single-stage combined craniofacial-transfacial approach that exposes the midline cranial base without visible facial incisions is described. METHODS: Between 1992 and 1998, eight patients underwent surgery for five different anterior cranial base pathological findings: four angiofibromas, one mesenchymal chondrosarcoma, one esthesioneuroblastoma, one odontogenic myxoma, and one encephalocele. In all cases, the surgical exposure consisted of a bicoronal scalp incision with a bifrontal craniotomy and fronto-orbitonasal osteotomy, and then a sublabial incision for transmaxillary exposure. RESULTS: Gross total resection was achieved in five cases. The encephalocele was resected with complete reconstruction of the bony defect. Seven patients developed complications, primarily wound infections, cerebrospinal fluid leaks, and anemia. Postoperative Karnofsky Performance Scale scores ranged between 80 and 100 (mean, 92.5). Long-term follow-up information (mean, 56 mo; median, 59.5 mo; range, 5–108 mo) was available for all patients. CONCLUSION: Large anterior cranial base lesions can be resected and excellent cosmetic outcomes can be achieved with a single-stage combined transfacial-craniofacial approach that exposes the entire midline cranial base and requires no facial incisions.

Results at 10–24 years after single-stage revision arthroplasty of infected total hip arthroplasty in patients under 45 years of age

2019 ◽  
pp. 112070001988887 ◽  
Author(s):  
Matthias Wolff ◽  
Christian Lausmann ◽  
Thorsten Gehrke ◽  
Akos Zahar ◽  
Malte Ohlmeier ◽  
...  
Keyword(s):  
Infection Control ◽  
Revision Surgery ◽  
Single Stage ◽  
Long Term Results ◽  
Harris Hip Score ◽  
Study Cohort ◽  
One Stage ◽  
The Mean

Introduction: The management of periprosthetic joint infection (PJI) of the hip is a challenging procedure. One-stage exchange is carried out in specialist centres with comparable infection free survival rates. However, there is a paucity of long-term results of this approach in young patients. Methods: All patients undergoing one-stage exchange due to PJI with a known causative organism ⩽45 years of age with a minimum of 10-year follow-up (mean 15 years; range 10–24 years) were enrolled in this retrospective study. Patients older than 45 years of age or patients with a two-stage procedure were excluded from the study. The primary outcome measure was failure rate with special focus on reinfection at latest follow-up. Failure was defined as revision surgery for infection. Furthermore, functional outcome using the Harris Hip Score was determined initially and at latest follow-up. 26 patients fulfilled the inclusion criteria and were available for final follow-up. Results: The study cohort consists of 16 male and 10 female patients with a mean age of 36.8 years (range 20–45 years) and a mean BMI of 29.8 kg/m2 (range 20.7–40.6 kg/m2). Prior to the single-stage procedure, the patients underwent an average of 3.1 previous surgical interventions (range 1–9). The mean hospital stay after septic revision was 19.7 days (11–33 days). Most infections were caused by Staphylococcus epidermidis ( n = 8, 30.8%), followed by Staph. aureus ( n = 7, 26.9%) and Propionibacterium acnes ( n = 6, 23.1%). At latest follow-up, the overall survival rate was 76.9 %, while infection control could be achieved in 96.2%. At final examination, the mean Harris Hip Score improved from 46.2 to 78.9 (range 18.0–99; SD, 22.6). Conclusions: Single-stage revision surgery for the management of PJI in patients ⩽45 years is a successful treatment option with high infection control, even after long-term follow-up.

scholarly journals Single-Stage Orbital Socket Reconstruction Using the Oversized Dermis Fat Graft and the 22 mm Silicone Orbital Implant after an Extended Enucleation

2018 ◽  
Vol 2018 ◽  
pp. 1-4
Author(s):  
Biljana Kuzmanović Elabjer ◽  
Mladen Bušić ◽  
Daliborka Miletić ◽  
Mirjana Bjeloš ◽  
Borna Šarić ◽  
...  
Keyword(s):  
Choroidal Melanoma ◽  
Single Stage ◽  
Long Term Results ◽  
Fat Graft ◽  
En Bloc ◽  
Orbital Implant ◽  
Absorbable Sutures ◽  
Previously Treated ◽  
Socket Reconstruction

We would like to present a surgical technique of orbital socket reconstruction using oversized dermis fat graft and 22 mm silicone orbital implant in a single-stage after extended enucleation in two patients with massive local recurrence of anteriorly located choroidal melanoma previously treated with endoresection. Orbital tissues en bloc were removed leaving conjunctival lining only at the fornices. Simultaneously, the 22 mm silicone sphere was implanted deeply into the orbit and covered with the oversized dermis fat graft of 30 mm in height and 35 mm in length with 20 mm of the fat thickness. The graft was sutured to the residual forniceal conjunctiva with interrupted 6/0 absorbable sutures overlapping conjunctiva with the graft edge for 2 mm to facilitate the epithelization. Epithelization was completed in two months, leaving well-formed fornices with good fitting of the prosthesis. The key point of orbital socket reconstruction after extended enucleation is to restore conjunctival lining prior to volume. Thus, whenever facing a massive volume and conjunctival lining loss, simultaneous insertion of the 22 mm silicone sphere deep into the orbit combined with oversized dermis fat graft is, in our opinion, the method of choice. It proved to be safe and effective with favourable long-term results.

Vesico-vaginal fistulas

1992 ◽  
Vol 59 (5) ◽  
pp. 34-37
Author(s):  
F. Pagano ◽  
A. Meneghini ◽  
G. Oliva
Keyword(s):  
Urinary Diversion ◽  
Single Stage ◽  
Technical Details ◽  
Transvesical Approach

— Fifty-four patients were treated at the Department of Urology, University of Padova for vesico-vaginal fistulas from May 1978 to June 1992. Twenty-six were operated by suprapubic transvesical approach with no long-term relapse. Twenty-eight patients presented complex vesico-vaginal fistulas: 23 were treated by single-stage transvesical repair. In 5 cases a urinary diversion was performed, ileal in 2 cases, colonic in 3. Only 1 case of relapse was observed (3.5%) in this group, and the patient was successfully re-operated. Authors underline classificative and etiologic factors involved in vesico-vaginal fistulas. Diagnostic and technical details of suprapubic transvesical repair are discussed.

scholarly journals Molar Growth Yields and Fermentation Balances of Lactobacillus casei L3 in Batch Cultures and in Continuous Cultures

1970 ◽  
Vol 63 (3) ◽  
pp. 333-345 ◽  
Author(s):  
W. De Vries ◽  
W. M. C. Kapteijn ◽  
E. G. Van Der Beek ◽  
A. H. Stouthamer
Keyword(s):  
Lactobacillus Casei ◽  
Growth Yields ◽  
Continuous Cultures ◽  
Batch Cultures
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