Optimization of nutritional supplements for enhanced lactic acid production utilizing sugar refinery by-products

In the present work Lactobacillus delbrueckii was used to utilize agro-industrial byproduct (cane molasses) for lactic acid production under submerged fermentation process. Screening of LAB was done by Fourier transform infra red spectroscopy (FTIR). Effect of different amino acids (DL-Phenylalanine, L-Lysine and DL-Aspartic acid) on the fermentation process was done by high performance liquid chromatography (HPLC). Central composite rotatable design (CCRD) was used to optimize the levels of three parameters viz. tween 80, amino acid and cane molasses concentration during fermentative production of lactic acid. Under optimum condition lactic acid production was enhanced from 55.89g/L to 84.50g/L. Further, validation showed 81.50g/L lactic acid production. Scale up was done on 7.5L fermentor. Productivity was found to be 3.40g/L/h which was higher than previous studies with reduced fermentation time from 24h to 12h. Further characterization of lactic acid was done by FTIR.

In the present study lactic acid production was enhanced by optimizing the three process variables viz; inoculum size, temperature and pH using three factor five level CCRD (central composite rotatable design) by Lactobacillus delbruckii under SMF (submerged fermentation process). Paneer (dairy by-product) whey was used as sole substrate for lactic acid production. Design Expert 8.0.2.0 software depicted that an optimum concentration of 8% (v/v) size of inoculum, 5.50 pH and 36.53C temperature gave lactic acid and biomass yield of 5.61 g/L and 4.27 g/L, respectively. Lactic acid production was scale up in 7.5 L bioreactor under optimized conditions and it gave lactic acid and biomass yield of 39.2±1.4 and 47.6±0.8 g/L, respectively. μg, YP/S, YP/X and productivity were found to be 0.14 h-1, 0.66 g/g, 0.7 g/g and 1.98 g/L. h, respectively. Leudking Piret equation deduced that lactic acid production was growth associated which varies from earlier reports. Lactic acid was characterized by FTIR (Fourier transform infrared spectroscopy) and HPLC (High performance liquid chromatography).

Continuous fermentation of clarified corn stover hydrolysate for the production of lactic acid at high yield and productivity

The continuous production of lactic acid from deproteinized whey by immobilized single and mixed culture of L. casei and L. lactis in Ca‐alginate beads has been investigated. A coimmobilized culture system gave better results than immobilized single cultures regarding lactic acid concentration, productivity, yield, and lactose utilization. Maximum lactic acid productivity of 7 g/lh was obtained at D=0.4 h−1 with a yield of 70% lactic acid and 50% lactose utilization. At a dilution rate of 0.1 h−1, a lactic acid productivity of 2.5 g/lh was obtained with a 55.5% lactic acid yield and 90% lactose utilization. The bioreactor system was operated at a constant dilution rate of 0.1 h−1 for 20 days without loss of original activity. In this case, the average lactic acid productivity, lactic acid yield and lactose utilization were 24 g/lh, 55% and 90%, respectively.

In the current work, date wastes were used for lactic acid (LA) production under thermo-alkaline conditions to overcome some fermentation challenges. Amongst 27 bacterial isolates that produced LA from date juice, isolate D-218 exhibited better growth stability and LA production under various stressed conditions. This isolate was characterized as Bacillus coagulans D-218 using physiological and molecular identification methods. In batch fermentation mode, strain D-218 could not completely utilize 80 g/L of the total sugar and produced only 45.8 ± 2.8 g/L of LA at LA productivity of 0.214 g/L.h and high residual sugar (29.2 g/L) was unutilized in the fermentation media. Different repeated batch fermentations with different initial sugar concentrations and gradual increase in sugar concentrtions were conducted to maximize LA productivity. Starting with 60 g/L of total sugar, four runs of repeated batch fermentations were conducted that enhanced the LA productivity (70%) to 0.49 g/L.h. Another 9 runs were initiated with 40 g/L which further improved LA productivity that reached up to 0.77 g/L.h. Surprisingly, initiating fermentations with 20 g/L of total sugar successfully attained long-term fermentation (18 runs) with high LA yield and productivity without carbon loss of initiated startup sugar of date waste. In this process, strain D-218 could completely consume 80 g/L sugars with high LA production titer (72.9 ± 0.56 g/L), yield (0.92 g/g), and productivity (0.71 g/L.h). This study is the first to exploit date waste in a cost-effective system for high-titer lactic acid production under thermo-alkaline conditions (pH 9.0; 50 °C) and to report repeated batch fermentation for LA production from date wastes.

The prospect of utilizing yam peel hydrolysate (YPH) as a carbon source for lactic acid (LA) production using Rhizopus orysae was investigated in batch surface and submerged fermentation processes. The kinetics of biomass growth, substrate utilization and LA production were studied using models of modified Luedeking–Piret, logistic and simple Luedeking–Piret equations, respectively, for the surface and submerged processes. The YPH containing 80 g L−1 of reducing sugars (glucose, xylose, ribose and others) was obtained by acid hydrolysis (H2SO4) of 100 g L−1 of yam peel and used for fermentation. The LA yield from the YPH was 80.03% and 75.63% for the surface and submerged fermentation, respectively. These values were higher than those of synthetic glucose syrup (SGS), which were 77.36% and 38.96% for surface and submerged fermentation, respectively. The models were satisfactory for the fermentation processes with high accuracy of R2 ((0.89 to 0.96), (0.95 to 0.99) and (0.86 to 0.99)) for biomass growth, substrate (SGS/YPH) utilization and LA production, respectively. The models also elucidated that the fermentation process was growth associated (α) instead of non‐growth associated (β) because the value of α/β was greater than 1. This justified the other kinetic parameters obtained for the growth phase. Therefore, Rhizopus oryzae effectively converted YPH to LA with a high yield and purity. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd

Lactic acid production by repeated fed-batch fermentation using free and immobilized cells of Lactobacillus lactis-11 in a packed bed-stirred fermentor (PBSF) system filled with different support materials including ceramic beads, macro-activated carbon cylinders and glass fiber balls was investigated. The results showed that the optimal support materials were the ceramic beads with diameters of 1-2 mm. Compared with the free cell fermentation system, lactic acid production and volumetric productivity in the PBSF system increased by 16.6 and 12.5%, respectively. Though the concentration of free cells decreased sharply, lactic acid production remained stable in five consecutive fed-batch runs using the PBSF system. pH gradients, immobilized cell concentration and mass diffusion in the packed bed were all affected by the recirculation rate of the culture broth. Maximum lactic acid production, productivity and yield occurred at a recirculation rate of 50 mL min(-1).

Lactic Acid as a platform chemical has broad application in various industries, especially in the production of Poly Lactic Acid (PLA) for biodegradable plastic. Empty fruit bunch (EFB), abundant by product from palm oil mill industry, is one of potential feedstock to be used in the production of lactic acid from lignocellulose biomass. EFB contains high cellulose and hemicellulose about 37– 59.7% w/w and 16–28% w/w, respectively. The aim of this paper is to study the effects of the operating conditions, such as temperature, reaction time, biomass loading, and catalyst concentration on the yield of lactic acid using barium hydroxide as alkaline catalyst. EFB pretreatment with steam explosion was applied to remove lignin content. The results showed that pretreatment reduced the lignin content from 22.66% to 9.69% w/w. Meanwhile, hemicellulose and cellulose increased from 14.40% to 16.40% w/w and 29.37% to 63.57% w/w, respectively. The highest yield of lactic acid was 21.57% C-mol, achieved by using 0.25 M Ba(OH)2 as the catalyst, with 5% w/v biomass loading, temperature 240°C, during 4 h reaction times. The yield was approximately equal to yield of lactic acid (~ 20%) compared with Pb2+ as the catalyst for EFB conversion although the later catalyst produced fewer by products during conversion.

Utilisation of microwave-NaOH pretreatment technology to improve performance and l-lactic acid yield from vinasse

Ethanol and lactic acid production as affected by sorghum genotype and location

Optimized feeding schemes of simultaneous saccharification and fermentation process for high lactic acid titer from sugarcane bagasse

Lactic acid fermentations were conducted using water hyacinth. It is known that the pretreatment and enzyme hydrolysis process optimize the potential of water hyacinth. Lactic acid produced by using lactic acid bacteria. All cells were grown at <TEX>$37^{\circ}C$</TEX> and initial pH 5.5. Lactic acid production was measured by HPLC. All Lactobacillus strains could produce lactic acid from pretreated water hyacinth. The highest lactic acid was achieved when lactic acid fermentation was carried out by L. delbrueckii for D-form and L. helveticus for L-form lactic acid production. The lactic acid concentration was 10.70 g/L by L. delbrueckii and it converted glucose in the medium to lactic acid, almost perfectly. Lactic acid production became higher when fermentation was carried out at a controlled pH 5.5. Lactic acid yield and productivity were 0.52 g/g and 0.19 g/L/h for L. helveticus, while L. delbrueckii was 0.64 g/g and 0.27 g/L/h. This study showed that water hyacinth medium could be alternative medium which can replace the complex and expensive medium for growing Lactobacillus strains in production of lactic acid.

Use of inexpensive nitrogen sources and starch for l(+) lactic acid production in anaerobic submerged fermentation

Production of lactic acid from paper sludge using acid-tolerant, thermophilic Bacillus coagulan strains

Photocatalytic conversion of biomass is considered an effective, clean, and environmentally friendly route to obtain high-valued chemicals and hydrogen. However, the limited conversion efficiency and poor selectivity are still the main bottlenecks for photocatalytic biomass conversion. Herein, we report the highly selective photocatalytic conversion of glucose solution on holo-symmetrically spherical three-dimensionally ordered macroporous TiO₂-CdSe heterojunction photonic crystal structure (s-TCS). The obtained s-TCS photocatalysts show excellent stability and strong light harvesting, uniform mass diffusion and exchange, and efficient photogenerated electrons/holes separation and utilization. The optimized s-TCS-4 photocatalyst displays the highest photocatalytic performance for glucose oxidation and hydrogen production. The glucose conversion, lactic acid selectivity, and yield on s-TCS-4 are about 95.9%, 94.3%, and 96.4%, respectively. The photocatalytic production of lactic acid for s-TCS-4 (18.5 g/L) is 2.3 times higher than the pure spherical TiO₂ photonic crystal without CdSe (s-TiO₂, 8.1 g/L), and the hydrogen production rate of s-TCS-4 is 9.4 times that of s-TiO₂. For the first time, we reveal that the photocatalytic conversion of glucose to lactic acid is a third-order and four-electron-involved reaction. This work could shed some new light on the efficient photocatalysis conversion of biomass to highly value-added products with high selectivity and yield, and simultaneously sustainable hydrogen evolution.