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Firstly, 2,3-butanediol (2,3-BDO) is a chemical platform used in several applications. However, the pathogenic nature of its producers and the expensive feedstocks used limit its scale production. In this study, cane molasses was used for 2,3-BDO production by a nonpathogenic Clostridium ljungdahlii . It was found that cane molasses alone, without the addition of other ingredients, was favorable for use as the culture medium for 2,3-BDO production. Compared with the control (i.e., the modified DSMZ 879 medium), the differential genes are mainly involved in the pathways of carbohydrate metabolism, membrane transport, and amino acid metabolism in the case of the cane molasses alone. However, when cane molasses alone was used, cell growth was significantly inhibited by KCl in cane molasses. Similarly, a high concentration of sugars (i.e., above 35 g/L) can inhibit cell growth and 2,3-BDO production. More seriously, 2,3-BDO production was inhibited by itself. As a result, cane molasses alone with an initial 35 g/L total sugars was suitable for 2,3-BDO production in batch culture. Finally, an integrated fermentation and membrane separation process was developed to maintain high 2,3-BDO productivity of 0.46 g·L -1 ·h -1 . Meanwhile, the varied fouling mechanism indicated that the fermentation properties changed significantly, especially for the cell properties. Therefore, the integrated fermentation and membrane separation process was favorable for 2,3-BDO production by C. ljungdahlii using cane molasses.

Phosphoric acid plus hydrogen peroxide (PHP) pretreatment was employed on wheat straw for ethanol conversion by simultaneous saccharification and fermentation (SSF) at high loadings. Results showed solid loading of PHP-pretreated wheat straw can be greatly promoted to 20%. Although more enzyme input improved ethanol conversion significantly, it still can be potentially reduced to 10-20 mg protein/g cellulose. Increasing yeast input also promoted ethanol conversion, however, the responses were not significant. Response surface method was employed to optimize SSF conditions with the strategy of maximizing ethanol conversion and concentration and minimizing enzyme and yeast input. Results indicated that ethanol conversion of 88.2% and concentration of 69.9 g/L were obtained after 120 h SSF at solid loading of 15.3%, and CTec2 enzyme and yeast were in lower input of 13.2 mg protein/g cellulose and 1.0 g/L, respectively. Consequently, 15.5 g ethanol was harvested from 100 g wheat straw in the optimal conditions., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Bacillus coagulans IPE22 was used to produce lactic acid (LA) from mixed sugar and wheat straw hydrolysates, respectively. All fermentations were conducted under non-sterilized conditions and sodium hydroxide was used as neutralizing agent to avoid the production of insoluble CaSO4. In order to eliminate the sequential utilization of mixed sugar and feedback inhibition during batch fermentation, membrane integrated repeated batch fermentation (MIRB) was used to improve LA productivity. With MIRB, a high cell density was obtained and the simultaneous fermentation of glucose, xylose and arabinose was successfully realized. The separation of LA from broth by membrane in batch fermentation also decreased feedback inhibition. MIRB was carried out using wheat straw hydrolysates (29.72 g/L glucose, 24.69 g/L xylose and 5.14 g/L arabinose) as carbon source, LA productivity was increased significantly from 1.01 g/L/h (batch 1) to 2.35 g/L/h (batch 6) by the repeated batch fermentation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Although bacterial cellulose (BC) is a fascinating, highly pure cellulose material for various downstream applications, production has been challenged by its low productivity. This work reported a facile route to significantly enhance BC yield without compromising its structural advantages via adding mesoporous halloysite nanotubes (HNTs) in the culture medium at static cultivations. The BC productivity of Gluconacetobacter xylinus was increased from 2.2 to 5.9 g L −1 after 15 days of cultivation when 2 wt% of HNTs was added into the standard fructose medium. It appeared that the dual functionality of cell immobilization and oxygen release of the HNTs were responsible for enhancing the BC productivity. Moreover, the HNTs-resulted BC pellicle exhibited negligible content of HNTs contamination (∼2 wt%), higher degree of crystallinity (87.7%) and porosity (assessed by water holding capacity, 12.7 g g −1 ), and showed promising applications especially in the bio-adsorption field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fermented sea buckthorn juice (FHJ) displayed better antioxidant and antidiabetic properties in vitro. • FHJ ameliorated diet-induced hyperlipidemia, insulin resistance, oxidative stress, and gut microbiota dysbiosis in vivo. • FHJ could interact with Akkermansia to further attenuate metabolic syndrome. • FHJ increased acetate and butyrate contents in caeca. • Fermentation-triggered metabolomic alterations, especially flavonoids in FHJ, played critical roles in the FHJ-microorganism interactions. To enhance physiological activity and probiotic availability of sea buckthorn juice, sea buckthorn juice pulp (BHJ) went through fermentation to the fermented (FHJ). In vitro , FHJ displayed better antioxidant and antidiabetic capacities. To further study effects of FHJ on diet-induced metabolic syndrome (MS) and possible mechanisms in vivo , C57BL/6 mice were fed on BHJ and FHJ under high fat diet (HFD). FHJ, rather BHJ, displayed better performance on ameliorating hyperlipidemia, insulin resistance, and oxidative stress in MS. Mechanistically, FHJ intervention significantly reversed the microorganism dysbiosis by restoring the microbial diversity, and modulating obesogenic bacteria abundance, like Oscillospira. Furthermore, fermentation altered FHJ's metabolomics, especially flavonoids, contributing to interactions between FHJ and probiotics, like Akkermansia and Lachnospiraceae. Furthermore, short-chain fatty acids, related to ameliorations of MS, were increased by FHJ. This study demonstrated that interactions between metabolomic alterations in FHJ and microorganisms were vital to attenuate MS. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nineteen elements were determined in rice wine from three different wineries. [•] Rice wines could be successfully classified according to their element profiles. [•] Discrimination was mainly attributed to water and other raw materials employed in fermentation. [Copyright &y& Elsevier]

The co-digestion of fruit & vegetable waste (FVW) and food waste (FW) was performed at various organic loading ratios (OLRs) in single-phase and two-phase system, respectively. The results showed that the ethanol-type fermentation dominated in both digestion processes when OLR was at low levels (<2.0 g(VS) L −1 d −1 ). The propionic acid was rapidly accumulated as OLR was increased to higher levels (>2.0 g(VS) L −1 d −1 ), which could cause unstable anaerobic digestion. Single-phase digestion was better than two-phase digestion in term of 4.1% increase in CH 4 production at lower OLRs (<2.0 g(VS) L −1 d −1 ). However, at higher level of OLR (⩾2.0 g(VS) L −1 d −1 ), two-phase digestion achieved higher CH 4 production of 0.351–0.455 L (g VS) −1 d −1 , which were 7.0–15.8% more than that of single-phase. Additionally, two-phase digestion presented more stable operation, and higher OLR treatment capacity. Furthermore, comparison of these two systems with bioenergy recovery revealed that two-phase system overall presented higher bioenergy yield than single-phase. [ABSTRACT FROM AUTHOR]

Abstract: In order to recycle the cotton-based waste textiles, a novel process was designed for pretreating waste textiles with phosphoric acid to recover polyester and fermentable sugar. The effects of pretreatment conditions including, phosphoric acid concentration, pretreatment temperature, time, and ratio of textiles and phosphoric acid were thoroughly investigated. Results indicated the mentioned four factors had significant influences on sugar and polyester recovery. Almost complete polyester recovery was achieved by enhancing phosphoric acid concentration, temperature and pretreatment time or reducing the ratio of textiles and phosphoric acid. However, these behaviors decreased the sugar recovery seriously. 100% polyester recovery with a maximum sugar recovery of 79.2% was achieved at the optimized conditions (85% phosphoric acid, 50°C, 7h, and the ratio of 1:15). According to the technical and cost-benefit analysis, it was technically feasible and potentially profitable to recover polyester and sugar from waste textiles by phosphoric acid pretreatment. [Copyright &y& Elsevier]

Abstract: In this work, separate hydrolysis and fermentation (SHF) and simultaneous saccharification fermentation (SSF) with high substrate consistency (the mass fraction: 12%) were performed with the steam-pretreated sweet sorghum bagasse (SSB). Fermentation ability of four yeast strains and influences of residual solids after hydrolysis on fermentation were investigated in SHF. Meanwhile, influences of inorganic salts on fermentation were assessed to determine their suitable supplementations for ethanol production. Additionally, influences of initial yeast inoculation on SHF and SSF were further investigated. The results showed the adopted yeast strain, Tembec 1, displayed the best fermentation performance on the hydrolysate of pretreated SSB, and the residual solids in hydrolysate had negligible influences on ethanol fermentation. Although the deficiency or overdose of (NH4)2HPO4 or MgSO4·7H2O could reduce ethanol yield in SHF, the suitable supplementation of (NH4)2HPO4 (0.5 g L−1) and MgSO4·7H2O (1.0 g L−1) could increase ethanol yield by 5.2% and 8.3%, respectively. The initial yeast inoculation of 3 g L−1 could satisfy both SSF and SHF, which achieved 63.8% and 57.9% ethanol yield of theoretical one with final ethanol concentration of 23.3 g L−1 and 21.2 g L−1, respectively. In addition, ethanol yield kept almost constant as yeast was inoculated from 3 to 5 g L−1 in SHF, whereas it decreased significantly in SSF. [Copyright &y& Elsevier]

Abstract: The experiments of ethanol fermentation from sweet sorghum stalk juice with immobilized yeast at different conditions, including temperature, pH, particles stuffing rate and initial substrate concentration, were carried out in 250ml shaking flasks to obtain suitable parameters by analyzing the values of ethanol formation rate (rp/s) and ethanol-sugar conversion ratio (Yp/s), respectively. The results indicated that fermentation temperature of 33°C, pH of 4.5, particles stuffing rate of 25% and the initial sugar concentrationof 218.1 mg·ml-1 could be selected. The results of verification experiments in 250ml shaking flasks with the corresponding conditions showed that the value of rp/s and Yp/s were 0.0486g·g-1·h-1 and 0.4005 g·g-1, respectively. In addition, the results of rp/s and Yp/s in the further verification experiments of 1L shaking flasks were 0.0465g·g-1·h-1 and 0.4248 g·g-1, respectively, which could be deduced that the selected conditions were suitable and reliable for ethanol production from sweet sorghum using immobilized yeast. [Copyright &y& Elsevier]

Abstract: Sweet sorghum bagasse (SSB) was steam-pretreated at various temperatures, residence times and SO2 impregnation dosages. A 23 factorial experimental design was employed to investigate the effects of temperature, residence time and SO2 impregnation and their interactions on enzymatic hydrolysis and ethanol production. The results showed that temperature, residence time, SO2 impregnation and the interaction of residence time and SO2 impregnation significantly affected enzymatic hydrolysis in an order of residence time>temperature>SO2 impregnation>the interaction of residence time and SO2 impregnation. Both of water-soluble and water-insoluble fraction derived from steam pretreatment were used for ethanol production, respectively. The results indicated that the effects of mentioned factors and their interactions on total ethanol yield were not significant. However, 200°C, 7.5min and 2.5% SO2 impregnation could be determined as a group of optimal pretreatment conditions, in which the highest ethanol yield of 15.3g/100g SSB (dry basis) could be obtained without pentose fermentation. [Copyright &y& Elsevier]

Abstract: Steam-pretreated sweet sorghum bagasse (SSB) and Douglas-fir (DF) were employed for SHF and SSF to evaluate the effects of xylanase supplementation and delignification on ethanol production. Results indicated final ethanol concentration in SHF could reach 28.4g/L (SSB) and 20.4g/L (DF) by xylanase supplementation with the increase of 46% and 61% in comparison with controls. The delignification could significantly enhance final ethanol concentration to 31.2g/L (SSB) and 30.2g/L (DF) with the increase of 61% and 138%. In SSF, final ethanol concentration in the delignified SSB and DF arrived at 27.6g/L and 34.3g/L with the increase of 26% and 157% compared with controls. However, only 2.2g/L (SSB) and 6.9g/L (DF) ethanol were obtained with xylanase supplementation. According to these results, it could be concluded that delignification was beneficial to improve ethanol production of SHF and SSF. The xylanase supplementation (0.12g protein/g glucan) was only positive to SHF while retarded SSF seriously. [Copyright &y& Elsevier]

Abstract: In order to attain a higher ethanol yield and faster ethanol fermentation rate, orthogonal experiments of ethanol fermentation with immobilized yeast from stalk juice of sweet sorghum were carried out in the shaking flasks to investigate the effect of main factors, namely, fermentation temperature, agitation rate, particles stuffing rate and pH on ethanol yield and CO2 weight loss rate. The range analysis and analysis of variance (ANOVA) were applied for the results of orthogonal experiments. Results showed that the optimal condition for bioethanol fermentation should be A4B3C3D4, namely, fermentation temperature, agitation rate, particles stuffing rate and pH were 37°C, 200rpm, 25% and 5.0, respectively. The verification experiments were carried out in shaking flasks and 5L bioreactor at the corresponding parameters. The results of verification experiments in the shaking flasks showed that ethanol yield and CO2 weight loss rate were 98.07% and 1.020gh−1, respectively. The results of ethanol fermentation in the 5L bioreactor showed that ethanol yield and fermentation time were 93.24% and 11h, respectively. As a result, it could be concluded that the determined optimal condition A4B3C3D4 was suitable and reasonable for the ethanol fermentation by immobilized Saccharomyces cerevisiae. The conclusion in the research would be beneficial for application of ethanol fermentation by immobilized S. cerevisiae from stalk juice of sweet sorghum. [Copyright &y& Elsevier]

Fructo-oligosaccharides (FOS) are prebiotics with numerous health benefits. So far, the dissolved oxygen (DO) concentration control strategy for fermentative production of FOS is still unknown. In order to improve FOS production, the effects of DO concentration and fermentation mode on FOS using Aureobasidium pullulans were investigated in this study. The greatest FOS production (123.2 ± 6.2 g/L), with a yield of 61.6% ± 3.0% (g FOS/g sucrose), was obtained in batch culture under high DO concentration. Furthermore, repeated-batch culture revealed that enzyme production and FOS production were not closely associated with cell growth. By keeping the DO concentration above 5% in the repeated-batch culture, a maximum FOS concentration of 548.3 ± 37.4 g/L and yield of 68.6% ± 2.6% (g FOS/g sucrose) were obtained, which were 3.45% and 11.4% times higher than those obtained in the batch culture without DO control, respectively. Additionally, the ratios of 1-fructofuranosyl nystose (GF4) and 1,1,1,1-kestohexose (GF5) were 33.8% and 23.2%, respectively, in the product of repeated-batch culture, but these compounds were not detected in batch culture. Thus, it can be concluded that the DO concentration affects not only the yield of FOS but also the composition of FOS with different degrees of polymerization, which is the key factor in the fermentative production of FOS with a high polymerization degree. [ABSTRACT FROM AUTHOR]

Wheat straw was pretreated by phosphoric acid plus hydrogen peroxide (PHP) for enzymatic hydrolysis and ethanol fermentation at high solid loadings. Results indicated solid loading could reach 20% with 77.4% cellulose-glucose conversion and glucose concentration of 164.9 g/L in hydrolysate, it even was promoted to 25% with only 3.4% decrease on cellulose-glucose conversion as the pretreated-wheat straw was dewatered by air-drying. 72.9% cellulose-glucose conversion still was achieved as the minimized enzyme input of 20 mg protein/g cellulose was employed for hydrolysis at 20% solid loading. In the corresponding conditions, 100 g wheat straw can yield 11.2 g ethanol with concentration of 71.2 g/L by simultaneous saccharification and fermentation. Thus, PHP-pretreatment benefitted the glucose or ethanol yield at high solid loadings with lower enzyme input. Additionally, decreases on the maximal cellulase adsorption and the direct-orange/direct-blue indicated drying the PHP-pretreated substrates negatively affected the hydrolysis due to the shrinkage of cellulase-size-accommodable pores. [ABSTRACT FROM AUTHOR]

This study was aimed at improving the nutrient composition of citrus pomace by solid-state fermentation with the autochthonous probiotics Lactobacillus plantarum P10, M14 and Bacillus subtilis BF2. The results showed that B. subtilis plays an important role in the release of phenolic components during fermentation, by increasing the cellulase, filter paperlyase, and pectinase activities. Co-fermentation with B. subtilis BF2 and L. plantarum P10 (BPF) increased the total phenolic content of CP by up to 133.15%, while single-bacteria fermentation with L. plantarum M14 significantly increased dietary fiber and organic acid content by 47.06% and 1429%, respectively. Furthermore, the phenolic fractions were markedly changed after fermentation, naringin and hesperidin were the main phenolic compounds in CP. They were highly correlated (r > 0.85, p < 0.05) with DPPH and ABTS+ radical scavenging abilities, which increased by 397.8% and 226.1%, respectively, when BPF was used. This study provides a potential method for producing high-value food or feed materials, with high antioxidant activities, from CP. [Display omitted] • Three kinds of autochthonous probiotics were isolated from citrus pomace (CP). • Fermentation with probiotics improved CP's dietary fiber and organic acid contents. • Phenolics and antioxidant activities were much enhanced by probiotic fermentation. • Co-fermentation increased the naringin and hesperidin content in CP. • CMCase, FPase, and pectinase played key roles in fermentation synergism. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between total soluble sugar content and Brix in stalk juice of sweet sorghum was determined through one-dimensional linear regression. Meanwhile, bioethanol fermentation experiments were conducted in shaking flasks and 10l fluidized bed bioreactor with stalk juice of Yuantian No. 1 sweet sorghum cultivar when immobilized yeast was applied. The experimental results in the shaking flasks showed that the order of influence on improving ethanol yield was (NH4)2SO4>MgSO4>K2HPO4, and the optimum inorganic salts supplement dose was determined as follows: K2HPO4 0%, (NH4)2SO4 0.2%, MgSO4 0.05%. When the optimum inorganic salts supplement dose was used in fermentation in 10l fluidized bed reactor, the fermentation time and ethanol content were 5h and 6.2% (v/v), respectively, and ethanol yield was 91.61%, which was increased by 9.73% than blank. In addition, the results showed that the fermentation time was about 6–8 times shorter in fluidized bed bioreactor with immobilized yeast than that of conventional fermentation technology. As a result, it can be concluded that the determined optimum inorganic salts supplement dose could be used as a guide for commercial ethanol production. The fluidized bed bioreactor with immobilized yeast technology has a great potential for ethanol fermentation of stalk juice of sweet sorghum. [Copyright &y& Elsevier]

• Mixing acid and enzyme hydrolysates as substrate was not good for PMLA production. • Integrated membrane process was used to recover sugar and acetate. • 1.46 g/L acetic acid promoted PMLA production and cell growth. • This process outperforms fermentation with glucose. Membrane-assisted β-poly(L-malic acid) (PMLA) production from bagasse hydrolysates was developed. For the first time, it was found that mixing the acid and enzyme hydrolysates was unfavorable for PMLA production because too high hexose: pentose ratio and glucose concentration in the mixed sugar could inhibit the assimilation of pentose. 120 g/L sugar concentrations in the acid hydrolysate was suitable for PMLA production with 23.2 g/L PMLA and 34.7 g/L biomass. Moreover, an integrated membrane process consisting of ultrafiltration, nanofiltration and reverse osmosis membranes could concentrate sugars and adjust acetic acid concentration prior to fermentation of lignocellulosic sugars. Meanwhile, it was found that 1.46 g/L acetic acid was preferred for PMLA production from enzyme hydrolysate or sole glucose which respectively increased PMLA production and cell growth by 25.4% and 5.9% from sole glucose, while it showed no significant enhancement in PMLA production with a higher cell growth and productivity from acid hydrolysate. [ABSTRACT FROM AUTHOR]

Baker's yeast industries generate highly polluted effluents, especially the cell free broth (i.e., vinasse) characterized by high chemical oxygen demand, nitrogen, and salts. In this work, it was found that the residual by-products (i.e., ethanol and acetic acid) and salts in the vinasse severely inhibited the cell growth, which hindered the reuse of the vinasse for the production of Saccharomyces cerevisiae. Through optimizing a suitable control strategy, the productions of ethanol and acetic acid were eliminated. Then, a nanofiltration membrane (i.e., NF5) was preferred for preliminarily and simultaneously separating and concentrating valuable molecules (i.e., invertase, food grade proteins and pigments) in the vinasse, and the main fouling mechanism was cake layer formation. Subsequently, a reverse osmosis membrane (RO) was suitable to separate and concentrate salts in the NF5 permeate, where the membrane fouling was negligible. Finally, the RO permeate was successfully reused for the production of S. cerevisiae. In addition, without calculating the benefit from the recovery of the valuable molecules, the cost of the integrated process can be decreased by 59.8% compared with the sole triple effect evaporation. Meanwhile, the volume of the fresh water used in the fermentation process can be decreased by 68.8%. Thus, it is a sustainable process for the cleaner production of baker's yeast using the integrated fermentation and membrane separation process. [Display omitted] • NF5 was preferred for recovering valuable molecules from vinasse. • NF5-RO process was suitable for resource recovery from vinasse. • The cost of the integrated process can be decreased by 59.8%. • 68.8% of water in fermentation can be saved using the integrated process. [ABSTRACT FROM AUTHOR]

A novel integrated isoelectric precipitation–nanofiltration (NF)–anaerobic fermentation process was proposed for fully recycling model dairy wastewater (MDW). Isoelectric precipitation at pH 4.80 and subsequent centrifugation could remove most proteins. Acetic and butyric acids from anaerobic fermentation were available for acidic precipitation, and the performance was comparable to that of hydrochloric acid. The pretreatment of MDW by precipitation could greatly retard NF membrane fouling, especially at pH 7.09 owing to the electrostatic repulsion between solutes and membrane. NF270 membrane was preferred for MDW concentration due to its high antifouling performance, high permeability and acceptable permeate quality. Anaerobic fermentation fed with model NF retentate without caseins produced higher proportion of acetate, butyrate and hydrogen, and this effluent with shorter-chain volatile fatty acids (VFAs) and lower pH was more suitable for casein precipitation in dairy wastewater. [ABSTRACT FROM AUTHOR]

Chopped rice straw fermentation in solid-state anaerobic digesters (SS-ADs) is a viable path for biogas generation. Thus, three fermentation test series in typical anaerobic digesters were operated to investigate the effects of the external surface area, permeability, and liquid fluidity of the solid-state bed (SSB) in improving anaerobic digestion, as determined by varying the tank height-to-diameter (H:D) ratio, SSB concentration, and leachate recirculation ratio (RR), respectively. In Series A, the H:D ratio impacted the modulation of digestion progress, including biogas generation, volatile fatty acids release, and lignocellulosic degradation. In Series B, the use of an SSB concentration below the inflection threshold (10.7 %–13.3%) for biogas production decline resulted in the highest methane yield and average methane content. In Series C, a 25.0% RR increased methane production significantly (P < 0.01) in both the semi-continuous fermentation SS-AD and downward plug-flow anaerobic digester (DPAD). Accordingly, energy flow analysis revealed that the DPAD produced 19.3% more net energy than the liquid anaerobic digester. [Display omitted] • Characteristic of the solid-state bed had an impact on digestion progress modulation. • Inflection threshold concentration of solid-state bed was 10.7%–13.3% TS. • Leachate recirculation could result in a significant methane production increment. • The solid-state anaerobic digester was more efficient than liquid anaerobic digester. [ABSTRACT FROM AUTHOR]

L(+)-lactic acid and its salts are being widely used in food and pharmaceutical industries. Rhizopus oryzae is known to be outstanding in producing optically pure L(+)-lactic acid. Rhizopus cultures are morphologically complex. They can grow as extended filamentous form, mycelial mats, mycelial pellets or clumps. Different morphology growth forms can have a significant effect on the rheology of the fermentation broth that will affect the performance of the bioreactor. The factors that affect the morphology and L(+)-lactic acid productivity of R. oryzae R1021 were investigated in detail in this work. Studies on the relationship among CaCO3 addition, inoculum size, concentration of NH4NO3, agitation speed, aeration rate and the morphology of the mycelial growth and lactic acid production were carried out. Uniform sized mycelial pellet growth (diameter of 1.0–2.0 mm) was obtained when the time of adding CaCO3 is 8 h after fermentation. The pellet form exhibited a higher lactic acid yield than clump form. An inoculated spore concentration of 106 spores/ml induced uniform pellet in preculture medium, and then formed the small mycelial pellets in production medium and a maximum L(+)-lactic acid concentration of 72.62 g/l was observed at the inoculum level of 3×106 spores/ml. Further studies on the effect of agitation speed on the fungal morphology showed that increasing agitation speed caused the fungal pellets to decrease in size but to increase in number per unit volume. Similar studies on the effect of aeration rate on the fungal morphology showed that increasing aeration rate caused the fungal pellets to increase in size but to decrease in number per unit volume. When agitation speed and aeration rate were 300 r/min and 0.6 vvm, the final L(+)-lactic acid concentration and the biomass concentration are 76.1 and 9.62 g/l, respectively, after 36 h culture of R. oryzae R1021 in pellet form (average pellet size, 1.4 mm) in stirred tank fermentor with initial glucose concentration of 100 g/l. L(+)-lactic acid production and the yield of L(+)-lactic acid based on the initial glucose are above 74.92 g/l and 74.2%, respectively, in 6 batches repetitive fermentation. [Copyright &y& Elsevier]