Initial Cell Concentration Research Articles

Formulation and Viability of Consortia LIBeM Using Protective Agent Skim Milk Subjected to Freeze Drying Method for Degradation of Oil Sludge Contaminated Soil

The formulation and viability of locally-isolated beneficial microorganisms (LIBeM) consortia was conducted by using protective agent skim milk at 30% (w/v). A 10% (v/v) of inoculum consists of mixed cultures C. tropicalis-RETL-Cr1+ C. violaceum-MAB-Cr1 + P. aeruginosa-BAS-Cr1 (RETL-Cr1+ MAB-Cr1+BAS-Cr1) were obtained from the Environmental Microbiology Laboratory, Universiti Malaysia Sabah and tested for biodegradation of oil sludge using the live cell powdered form. LIBeM formulation was carried out by using lyophilization under vacuum conditions for 24 hours. The viability of the initial cell loads on the final recovery after freeze drying process was measured weekly by heterotrophic plate counts (HPC). Surface morphological of LIBeM powder (LiBeM-POW) was observed under scanning electron microscopy (SEM) to show any changes on the surface cell structures. The results showed that the use of 10% (v/v) of inoculum with 108 CFU/ mL as initial cell concentrations and 30% (w/v) skim milk as protective agent yielded 31.9% maximum viability. The findings also indicate that the survival rate of LIBeM cells have potential to survive and functionality even after 13 weeks of the storage with 106 CFU/ mL recorded. The effectiveness of microbial formulation of LiBeM-POW was done by carrying out the biodegradation experiment in ASP-bioreactor system for 56 days. Two sets of ASP- bioreactor system containing 2 kg of soil mixed with 20% (v/v) of oil sludge were prepared as T1: treatment with consortia LIBeM-POW and T2: natural attenuation as a control plot. The results indicated that LIBeM-POW has potential to be applied in bioremediation of oil sludge contaminated environments with 92% degradation of TPH as compared to natural attenuation 26% degradation. This finding suggests the possibility of producing freeze dried powder of LIBeM consortia with high viability for prior used in bioremediation study. The comparison of other protective agent used by previous studied was also discussed in this paper.

An integrated enrichment-detection platform for identification of contamination of Vibrio parahaemolyticus in food samples

A novel and rapid method to identify contamination of Vibrio parahaemolyticus during an enrichment was developed. The principle was based on the bacteria's capability of carbohydrate fermentation and amino acid decarboxylation. Six different broths were developed with four sugar substrates, namely, dextrose (DEX), arabinose (ARA), mannose (MAO), mannitol (MAI), and two amino acids, namely, lysine (LYS) and ornithine (ODB). Bromocresol purple (BP) and phenol red (PR) were added to detect pH changes of the broths. The absorbance of the color change was determined for all sugar broths at 600 nm and both amino acids at 550 nm. Salinity and pH were adjusted to suppress competitive bacteria. The optimal conditions for the sugar substrates and the amino acids were 8% NaCl/pH = 9.0 and 6% NaCl/pH = 6.0, respectively. In real samples, this method was capable of detecting V. parahaemolyticus with a limit of detection of 0.1–1.0 log CFU/mL (measured as an initial cell concentration in the samples). At 24 h, this method also yielded a 100% sensitivity and improved a specificity to 95%–100%, compared to the 88% specificity as obtained in the conventional method. Integrating the detection of V. parahaemolyticus provided a quick and effective screening for the presence of V. parahaemolyticus.

Determination of live and dead Komagataeibacter xylinus cells and first attempt at precise control of inoculation in nanocellulose production.

SummaryThe timely enumeration of cells of nanocellulose‐producing bacteria is challenging due to their unique growth properties. To better understand the metabolism of the bacteria and better control the concentration of living cells during cultivation, a prompt cell counting technology is crucial and urgently required. In this work, two fluorescent dyes, the asymmetrical anthocyanidin dye SYBR Green I (SG) and propidium iodide (PI), were first combined for Komagataeibacter xylinus species to determine live/dead bacterial cells quantitatively and promptly. The number of live and dead K. xylinus cells determined using an epifluorescence microscope corresponded well to the results obtained using a fluorescence microplate reader. The R 2 values were 0.9986 and 0.9920, respectively, and were similar to those obtained with the LIVE/DEAD® BacLightTM commercial kit. SG/PI double‐staining showed proper efficiency in distinguishing live/dead cells for the K. xylinus strain (R 2 = 0.9898). The technology was applied to standardize four different K. xylinus strains, and the initial cell concentration of the strains was precisely controlled (no significant difference among the strains, P> 0.05). The cellulose yield per live cell was calculated, and significant differences (P < 0.05) were found among the four strains in the following order: DHU‐ATCC‐1> DHU‐ZCY‐1> DHU‐ZGD‐1> ATCC 23770. The study shows (i) the application of the SG/PI staining to standardizing inocula for bacterial cellulose production so that a more accurate comparison can be made between different strains, and (ii) the lower cost of using SG rather than the SYTO 9 of the commercially available LIVE/DEAD® BacLightTM kit.

Growth Parameters and Survivability of Saccharomyces boulardii for Probiotic Alcoholic Beverages Development.

The aim of this research was to optimize the growth parameters (pH, ethanol tolerance, initial cell concentration and temperature) for Saccharomyces boulardii and its tolerance to in vitro gastrointestinal conditions for probiotic alcoholic beverage development. Placket-Burman screening was used to select only statistically significant variables, and the polynomial mathematical model for yeast growth was obtained by central composite rotatable design. Confirmation experiments to determine the kinetic parameters for yeast growth were carried out by controlling the temperature and pH. Soon after, the survivability of yeast was tested under in vitro conditions mimicking the human upper gastrointestinal transit. S. boulardii had suitable resistance to alcohol and gastrointestinal conditions for probiotic alcoholic beverage development.

Effects of initial cell concentration, growth phase, and process parameters on the viability of Lactobacillus rhamnosus GG after spray drying

During spray drying, probiotics encounter several stresses which can reduce their viability. To obtain powder with a sufficient amount of viable probiotics, we evaluated the effects of different process parameters, such as initial cell concentration and the bacterial growth phase, on the viability of the model probiotic Lactobacillus rhamnosus GG. Increasing the initial biomass did not positively impact bacterial viability after spray drying. For growth, we found that stationary grown bacterial cells were more resistant to the spray-drying process than mid-log grown cells, probably owing to an initiated stress response. Furthermore, a full factorial 3³ design was used to assess the influence of three different conditions of inlet temperature, feed rate, and atomizing air flow on the outlet temperature and bacterial viability after spray drying. As expected, inlet temperature had the largest influence on both outlet temperature and log-reduction in bacterial viability. An interaction effect was also observed between feed rate and inlet temperature. Considering the viability of L. rhamnosus GG, the optimal outlet temperature ranged between 50 and 60 °C for obtaining powders with the lowest log-reductions in viability.

Dynamic modelling, simulation and economic evaluation of two CHO cell-based production modes towards developing biopharmaceutical manufacturing processes

Chinese Hamster Ovary (CHO) cells are widely used in fermentation towards biopharmaceutical manufacturing. The present paper presents dynamic mathematical models of two different CHO culture modes: one batch mode for the production of interferon (IFN)-γ, and one perfusion mode for the production of a monoclonal antibody (mAb). The dynamic models have been used for simulating cell, substrate, by-product and product concentration trajectories, which have been compared against previously published experimental results. A sensitivity analysis of both models has been conducted, in order to analyse the relative importance of different operating parameters towards biopharmaceutical process design. An economic analysis has also been subsequently performed: production time and net present cost for given target capacities have been evaluated, using the validated dynamic models for the batch and perfusion modes. Economic trends are discussed for variable initial concentration of viable CHO cells to be used in bioreactors: the latter has been recognised as the most sensitive model parameter for both culture modes.

Short communication: Bioinformatics-based mining of novel gene targets for identification of Cronobacter turicensis using PCR

Cronobacter turicensis is a food-borne pathogen found in dairy products. It has been reported to cause bacteremia and enteritis in immunocompromised people, especially infants. Cronobacter turicensis has been isolated from various food sources, and contaminated powdered infant formula was found to be the most common source of infection among infants. Although some gene targets are used for the identification of C. turicensis, they are not specific at the species level. In this study, we analyzed the genome sequence of C. turicensis by bioinformatics and identified 13 specific gene targets. Primer sets targeting these sequences were designed and selected based on their specificity. Finally, primer set CT11, targeting gene CTU_19580, which codes for a hypothetical protein, was selected for development of the PCR assay because it alone produced positive PCR results for C. turicensis. To our knowledge, this is the first time that this gene target has been used to develop PCR detection assays for C. turicensis. The specific PCR assay had detection limits as low as 760 fg/µL for genomic DNA (approximately 158 copies/μL of DNA) and could detect C. turicensis in powdered infant formula with initial cell concentrations as low as 8.5 cfu per 10 g of powdered infant formula after 10 h of enrichment. Thus, this PCR assay is highly sensitive and can be used for rapid detection of C. turicensis.

T-Cell mediated adaptive immunity and antibody-dependent enhancement in secondary dengue infection

Dengue infection results in a significant number of deaths, mostly in the tropical and subtropical regions across the world. Yet, despite the seriousness of this disease, vaccine, and antiviral drugs that could be employed in dengue treatment remain elusive. The desire to establish the factors determining the disease severity and the growing need for efficient drugs has prompted extensive research interest in within-host viral dynamics. However, very few mathematical models of within-host dengue dynamics pertaining to secondary dengue infection with another serotype are presently available. To address this gap in the pertinent literature, in this work, a secondary dengue infection model with T-cell mediated adaptive immunity and antibody-dependent enhancement was developed by considering the memory cell and heterogeneous antibody as the main factor. In particular, the explicit role of cytokines is considered for both virus and infected cell clearance, along with both extrinsic and intrinsic mechanisms for antibody-dependent enhancement. In case of secondary dengue infection, both the virus and homogeneous antibody production are enhanced due to the influence of memory cells remaining from the previous (primary) dengue infection. Owing to the high model sensitivity, it was possible to establish that, among antibody-dependent enhancement mechanisms, the increased virus replication inside the infected cell, which increases the overall virus burst size, exerts the maximum effect on disease severity during secondary infection. Moreover, the role of initial memory cell concentrations and half-saturation constant in the secretion of memory cell in the disease severity was studied. The obtained results concur with the clinical observations and may be helpful in further research on antibody-dependent enhancements aimed at producing schemes relevant for the dengue vaccine design and development.

Evaluation of Rice Bran as a Supplement for Production of Bioethanol by Saccharomyces cerevisiae

ABSTRACT There is an increase in researches to create alternative fuels through the use of biomass and agroindustrial lignocellulosic residues. The present study proposes the use of rice bran as source of energy with the potential to enhance bioethanol production. Using different concentrations of cells (1-5 g.L–1) and rice bran (2.5-7.5 g.L –1) with Saccharomyces cerevisiae, a factorial design 22 was carried out. The nutrient source provided by rice bran affects the substrate conversion in product (Yp/s) response in a quadratic form, but its linear form showed no significant effect (α = 0.05). When it comes to means, the best results were obtained for 12 h and for fermentation medium 2 (23.320 g.L–1 of ethanol), which contained the highest rice bran concentration and the lowest initial cell concentration. Medium 3, consisting of 2.5 g.L–1 and 5 g.L –1 of rice bran and cells, respectively, showed the lowest K s (4.434 g.L–1).

Enhancement of chicken primordial germ cell in vitro maintenance using an automated cell image analyser.

Primordial germ cells (PGCs) were isolated from blood samples of chicken embryos. We established four PGC lines: two males (FS-ZZ-101, GFP-ZZ-4ZP) and two females (FS-ZW-111, GFP-ZW-5ZP). We could not detect a significant difference in the marker expression profile, but there was a remarkable difference between the proliferation rates of these PGC lines. We monitored the number of PGCs throughout a three-day period using a high-content screening cell imaging and analysing system (HCS). We compared three different initial cell concentrations in the wells: ~1000 cells (1×, ~4000 (4× and ~8000 (8×. For the GFPZW- 5ZP, FS-ZZ-101 and FS-ZW-111 PGC lines the lowest doubling time was observed at 4× concentration, while for GFP-ZZ-4ZP we found the lowest doubling time at 1× concentration. At 8× initial concentration, the growth rate was high during the first two days for all cell lines, but this was followed by the appearance of cell aggregates decreasing the cell growth rate. We could conclude that the difference in proliferation rate could mainly be attributed to genotypic variation in the established PGC lines, but external factors such as cell concentration and quality of the culture medium also affect the growth rate of PGCs.

Screening and safety evaluation of lactic acid bacteria with selenium adsorption capacity

Selenium, one of the essential trace elements in humans and animals, is involved in various biochemical and physiological functions, such as improving immunity and antioxidant properties. Lactic acid bacteria, recognized as generally recognized as safe (GRAS) in the world, have the ability to convert inorganic selenium into organic form and have plenty of outstanding probiotic properties, including regulation of gut microbiota, increase of antioxidant capacity, and decrease of intestinal inflammation and so on. Therefore, using them as a safe and efficient selenium supplementation carrier is increasingly becoming a hotspot in recent research. In order to obtain a strain of lactic acid bacteria with good selenium adsorption capacity, 43 strains of Lactobacillus of different species were screened by determining the adsorption rate of selenium in vitro . The adsorption conditions were as follows: The initial selenium concentration was 50 mg/L, the initial cell concentration was 1 g/L, and the adsorption time was 1 h. The selenium adsorption rate and selenium adsorption capacity of the strains were determined by measuring the selenium content of the dried bacteria after nitrolysis. The selenium levels were determinated by inductively coupled plasma mass spectrometer (ICP-MS). At the same time, the adsorption characteristics of the strain were studied by changing the initial pH, initial cell concentration, initial selenium concentration and adsorption time, and acid and bile salt tolerance were determined to confirm whether it can still maintain high activity in the gastrointestinal tract. Then the safety of the strain was evaluate by the acute toxicity test and the 30-d feeding experiment, as well as antibiotic resistance of the strain. The results showed that the Lactobacillus plantarum RS7-1 had the most excellent selenium adsorption ability among the 43 strains, and its adsorption rate for selenium was up to 40.79%±1.27%. The optimum pH of the strain was 5.0, and the optimal initial bacterial concentration was 2 g/L. The maximum adsorption capacity was reached when the initial selenium concentration was 20 mg/L. The adsorption of selenium can be divided into two stages, rapid adsorption stage and adsorption equilibrium stage. The equilibrium time was reached when the adsorption time was 60 min. At the same time, the strain has outstanding acid and bile salt tolerance, without species-specific antibiotic tolerance, and after safety evaluation, the mice fed with the strain shows no significant difference in the food consumption, body weight, biochemical index, hematological indexes of blood compared with mice in blank group, and no organ and tissue lesions were detected. In conclusion, Lactobacillus plantarum RS7-1 is a strain of lactic acid bacteria with superb selenium adsorption capacity, great acid and bile salt tolerance, without toxicity and side effect. This study provides an idea for the selenium supplement with probiotics as the carrier, and the selenium adsorption capacity can be further improved by optimization of adsorption conditions, mutation breeding and genetic engineering, thereby increasing the application value of selenium-enriched probiotic products in the future.

Finite-Element Syntheses of Callus and Bone Remodeling: Biomechanical Study of Fracture Healing in Long Bones.

Computational simulations of fracture healing are a valuable tool to improve fracture treatment and implants. Several finite-element models have been established to predict callus formation due to mechanobiological rules. This work provides a comprehensive simulation for virtual implantation through the combination of callus simulation and finite-element structural synthesis (FESS) of (re-)modeling during and after healing based on Pauwel's theory of histogenesis and Wolff's law. The simulation is based on a linear elastic material model and includes generation of fracture hematoma and initial mesenchymal stem cell concentration out of an unspecified solid, cell proliferation, migration, and differentiation due to mechanical stimuli and time-dependent axial loading. Three nondisplaced femoral shaft fractures with initial interfragmentary movement of 0.2, 0.6, and 1 mm and one fracture with 4 mm translation are modeled. The predictions of interfragmentary movement during fracture healing, healing success, and healing time agree with observed clinical outcome, animal models, and other numerical models. Initial interfragmentary movement between 0.2 and 1 mm leads to healing success, with the fastest healing occurring at 0.2 mm. The model of the dislocated fractures shows no further bending after remodeling and is loaded with physiological stress of -13 MPa. Ideal load-time graphs may give insight into the bone's ability to withstand loads as healing time progresses, and thus holds potential for applications in rehabilitation planning. Better knowledge of the forces present during fracture healing is needed to deploy simulations for surgical planning and manufacturing of patient individualized implants. Anat Rec, 301:2112-2121, 2018. © 2018 Wiley Periodicals, Inc.

Cell Transport Prompts the Performance of Low-Voltage Electroporation for Cell Inactivation

The inactivation of pathogens in liquids has broad applications, ranging from water disinfection to food pasteurization. However, common cell inactivation methods (e.g., chlorination, ultraviolet radiation and thermal treatment) have significant drawbacks such as carcinogenic byproduct formation, energy intensiveness and/or nutrient structure destruction. Here, we fabricated a new approach to address these challenges by applying a low-voltage electroporation disinfection cell (EDC) and investigate the critical mechanisms of cell transport to allow high inactivation performance. The EDC prototypes were equipped with two one-dimensional (1D) nanostructure-assisted electrodes that enabled high electric field strength (>107 V m−1) near the electrode surface with a low applied voltage (1 V). We have identified that during electroporation disinfection, electrophoresis, dielectrophoresis and hydraulic flow are the three major mechanisms which transport cells into the vicinity of the electrode surface to achieve superior disinfection performance. The EDC treated 70 ml of bacteria sample with an initial cell concentration of 107 CFU ml−1 and achieved complete bacteria inactivation (survival rate <0.00001%; no live bacteria detected). Our findings will help to establish a foundation for the future development and implementation of low-voltage electroporation for cell inactivation.

Czynniki warunkujące zjawisko allelopatii u sinic i mikroglonów w ekosystemach wodnych

Allelopatia w środowisku wodnym może być narzędziem walki o zasoby pomiędzy organizmami wodnymi. Badania terenowe i prace laboratoryjne wykazały, że allelopatia może występować zarówno w ekosystemach morskich, brakicznych, jak i słodkowodnych. Związki allelopatyczne mogą negatywnie oddziaływać zarówno na wodnych producentów pierwotnych, jak i na skorupiaki, małże, ryby, ssaki, a nawet organizm człowieka. Jednakże stosunkowo niewiele czynników środowiskowych było dokładnie badanych pod kątem ich wpływu na produkcję związków allelopatycznych, dlatego rozpoznanie takie jest niedostateczne. Obecnie występują nieliczne prace, w których udokumentowano wpływ czynników biotycznych lub abiotycznych na występowanie oddziaływania allelopatycznego. Do najczęściej opisywanych czynników biotycznych, wpływających na oddziaływanie allelopatyczne, zalicza się samą specyfikę badanych organizmów, ich rozmiar, zagęszczenie początkowe komórek, fazę wzrostu organizmów donorowych i docelowych oraz ilość i częstotliwość dodawania przesączu komórkowego. Natomiast czynnikami abiotycznymi, które mogą mieć wpływ na zjawisko allelopatii u sinic i mikroglonów są intensywność napromieniowania, temperatura oraz dostępność składników pokarmowych. Chcąc lepiej ocenić znaczenie zjawiska allelopatii w zbiornikach wodnych, potrzebne są dalsze badania czynników środowiskowych, które wpływają na produkowanie i wydzielanie aktywnych związków allelopatycznych. Zrozumienie wpływu czynników środowiskowych na produkowanie i wydzielanie związków allelopatycznych przez sinice i mikroglony oraz ich roli w ekosystemach wodnych powinno stać się ważnym zadaniem przyszłych badań.

A model-based optimization of microalgal cultivation strategies for lipid production under photoautotrophic condition

Increasing the lipid production rate stands as one of the challenges for achieving economic feasibility of microalgal biorefinery. Various bioreactor operation strategies have been considered for culturing microalgae, including batch, continuous, fed-batch, semi-batch, and two-stage operations. However, since the previous studies used different experimental criteria, it is hard to draw a conclusion about their relative performances. Motivated by this, the present study compares lipid productivity performances and capital expenditures of the various operation strategies after their operating conditions are optimized. The optimal condition for each strategy is determined by performing a model-based optimization to maximize lipid productivity, which is a good indicator of the overall economics. The two-stage operation with continuous-batch serial connection (w/ stress condition) and the semi-batch operation (w/o stress condition) show outstanding performance compared to the other types of operation. Also, start-up, initial cell concentration, and chemical consumption, which are critical factors in large-scale cultivation, are analyzed.

Calibration of Multi-Parameter Models of Avascular Tumor Growth Using Time Resolved Microscopy Data

Two of the central challenges of using mathematical models for predicting the spatiotemporal development of tumors is the lack of appropriate data to calibrate the parameters of the model, and quantitative characterization of the uncertainties in both the experimental data and the modeling process itself. We present a sequence of experiments, with increasing complexity, designed to systematically calibrate the rates of apoptosis, proliferation, and necrosis, as well as mobility, within a phase-field tumor growth model. The in vitro experiments characterize the proliferation and death of human liver carcinoma cells under different initial cell concentrations, nutrient availabilities, and treatment conditions. A Bayesian framework is employed to quantify the uncertainties in model parameters. The average difference between the calibration and the data, across all time points is between 11.54% and 14.04% for the apoptosis experiments, 7.33% and 23.30% for the proliferation experiments, and 8.12% and 31.55% for the necrosis experiments. The results indicate the proposed experiment-computational approach is generalizable and appropriate for step-by-step calibration of multi-parameter models, yielding accurate estimations of model parameters related to rates of proliferation, apoptosis, and necrosis.

Control of the culture conditions of Chlamydomonas reinhardtii for efficient delivery of exogenous materials in electroporation

The effects of microalgae culture conditions on the exogenous material delivery efficiency in electroporation were investigated. The exogenous material delivery into C. reinhardtii by electroporation was significantly affected by the cell growth phase state. The delivery efficiency of nucleic acid stain Yo-Pro-1 was maximized when mid log growth phase cells were used whereas the CFP transfection efficiency was maximized when late log phase cells were used. By controlling initial cell concentration and light condition, we could control cell growth and exogenous material delivery efficiency. By increasing initial cell concentration, the required time to reach mid log growth phase could be reduced but the corresponding Yo-Pro-1 delivery efficiency decreased. The diurnal light induced 20% lower saturated cell concentration than continuous light and it made positive effects on exogenous material delivery and DNA transfection. According to the present findings, it is recommended to harvest late log phase C. reinhardtii cells for more efficient transformation. The significance and implication of the present work for microalgae transformation and future work are discussed.

Smart Cell Culture Monitoring and Drug Test Platform Using CMOS Capacitive Sensor Array.

This paper presents a novel method for monitoring drug cytotoxicity using a hybrid microfluidic CMOS platform. This platform consists of an array of 8 × 8 capacitive sensors integrated with a readout circuit on the same chip. In this paper, we present a layer-by-layer (LBL) polyelectrolyte deposition technique to coat the surface of microelectrodes realized in the top most metal layer in 0.35-μm CMOS process. This process successfully enhances the biocompatibility of sensing microelectrodes and consequently increases the cell viability over a three-day period. Herein, we demonstrate and discuss the advantage of the proposed platform for drug cytotoxicity as well as cellular growth monitoring. This CMOS sensing platform possesses a wide output dynamic range and allows tracking cell growth at initial cell concentrations ranging from 10 to 200k Cells/ml. We also use a standard Alamarblue cell-based assay and Geneticin selective antibiotic (G418) as control and cytotoxic drugs introduced to non-resistant H1299 and resistant Hek293 cell lines, respectively. Furthermore, a low complexity microfluidic packaging technique is presented to create and bond micro-wells on CMOS chip for rapid test and characterization. With the potential to perform label-free cellular analysis, the proposed platform opens an avenue to transition from traditional to smart cellular analysis techniques suitable for a variety of biological applications, in particular high throughput cell-based drug testing.

A rapid method for harvesting and immobilization of oleaginous microalgae using pellet-forming filamentous fungi and the application in phytoremediation of secondary effluent

ABSTRACTA rapid method for harvesting and immobilization of oleaginous microalgae using pellet-forming filamentous fungi was developed. The suitable conditions for pellet formation by filamentous fungi were determined. Among the strains tested, Trichoderma reesei QM 9414 showed superior pellet forming ability. Its pellets were used to harvest oleaginous microalga Scenedesmus sp. With increasing volume ratio of fungal pellets to microalgae culture up to 1:2, >94% of microalgal cells were rapidly harvested within 10 min. The ratio of fungal pellets could manipulate both harvesting time and initial concentration of microalgal cells in the pellets. The microalgae–fungal pellets were successfully used as immobilized cells for effective phytoremediation of secondary effluent from seafood processing plants under nonsterile condition. The chemical oxygen demand, total nitrogen, and total phosphorus removal were >74%, >44%, and >93%, respectively. The scanning electron microscopy showed that the microalgal cells were not only entrapped in the pellets but also got attached to the fungal hyphae with sticky exopolysaccharides, possibly secreted by the fungi. The extracted lipids from the pellets were mainly composed of C16–C18 (>83%) with their suitability as biodiesel feedstocks. This study has shown the promising strategy to rapidly harvest and immobilize microalgal cells and the possible application in phytoremediation of industrial effluent.

Repeated ethanol fermentation from membrane-concentrated sweet sorghum juice using the flocculating yeast Saccharomyces cerevisiae F118 strain

The aim of this study was to construct a cost-effective method for repeated bioethanol production using membrane (ultrafiltration permeation and nanofiltration concentration)-concentrated sweet sorghum juice by using flocculent Saccharomyces cerevisiae F118 strain. With low initial dry cell concentrations at around 0.28–0.35 g L−1, the S. cerevisiae F118 strain provided an ethanol titer of 86.19 ± 1.15 g L−1 (theoretical ethanol yield of 70.77%), which was higher than the non-flocculent S. cerevisiae BY4741 strain at 33.92 ± 0.99 g L−1 after 24 h fermentation. This result was correlated with higher gene expressions of the sucrose-hydrolysing enzyme invertase, sugar phosphorylation, and pyruvate-to-ethanol pathways in the F118 strain compared with the BY4741 strain. Sequential fed-batch fermentation was conducted, and the F118 strain was easily separated from the fermentation broth via the formation of flocs and sediment. After the 5th cycle of fermentation with the F118 strain, the ethanol concentration reached 100.37 g L−1.