Phosphatase production by a Citrobacter sp. growing in batch culture and use of batch cultures to investigate some limitations in the use of polyacrylamide gel-immobilized cells for product release

Eggshell waste bioprocessing for sustainable acid phosphatase production and minimizing environmental hazards

BACKGROUND

The Environmental Protection Agency has listed eggshell waste as the 15th most significant food industry pollution hazard. Using eggshell waste as a renewable energy source has been a hot topic recently. Therefore, finding a sustainable solution for the recycling and valorization of eggshell waste by investigating its potential to produce acid phosphatase (ACP) and organic acids by the newly-discovered B. sonorensis was the target of the current investigation.

RESULTS

Drawing on both molecular and morphological characterizations, the most potent ACP-producing B. sonorensis strain ACP2, was identified as a local bacterial strain obtained from the effluent of the paper and pulp industries. The use of consecutive statistical experimental approaches of Plackett-Burman Design (PBD) and Orthogonal Central Composite Design (OCCD), followed by pH-uncontrolled cultivation conditions in a 7 L bench-top bioreactor, revealed an innovative medium formulation that substantially improved ACP production, reaching 216 U L-1 with an ACP yield coefficient Yp/x of 18.2 and a specific growth rate (µ) of 0.1 h-1. The metals Ag+, Sn+, and Cr+ were the most efficiently released from eggshells during the solubilization process by B. sonorensis. The uncontrolled pH culture condition is the most suitable and favoured setting for improving ACP and organic acids production. Quantitative and qualitative analyses of the produced organic acids were carried out using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Lactic acid, citric acid, and hydroxybenzoic acid isomer were the most common organic acids produced throughout the cultivation process. The findings of TGA, DSC, SEM, EDS, FTIR, and XRD analysis emphasize the significant influence of organic acids and ACP activity on the solubilization of eggshell particles.

CONCLUSIONS

This study emphasized robust microbial engineering approaches for the large-scale production of a newly discovered acid phosphatase, accompanied by organic acids production from B. sonorensis. The biovalorization of the eggshell waste and the production of cost-effective ACP and organic acids were integrated into the current study, and this was done through the implementation of a unique and innovative medium formulation design for eggshell waste management, as well as scaling up ACP production on a bench-top scale.

Bioprocess development as a sustainable platform for eco-friendly alkaline phosphatase production: an approach towards crab shells waste management

Background

There are substantial environmental and health risks associated with the seafood industry's waste of crab shells. In light of these facts, shellfish waste management is critical for environmental protection against hazardous waste produced from the processing industries. Undoubtedly, improved green production strategies, which are based on the notion of "Green Chemistry," are receiving a lot of attention. Therefore, this investigation shed light on green remediation of the potential hazardous crab shell waste for eco-friendly production of bacterial alkaline phosphatase (ALP) through bioprocessing development strategies.

Results

It was discovered that by utilizing sequential statistical experimental designs, commencing with Plackett–Burman design and ending with spherical central composite design, and then followed by pH-uncontrolled cultivation conditions in a 7 L bench-top bioreactor, an innovative medium formulation could be developed that boosted ALP production from Bacillus licheniformis strain ALP3 to 212 U L⁻¹. The highest yield of ALP was obtained after 22 h of incubation time with yield coefficient Y_p/s of 795 U g⁻¹, which was 4.35-fold higher than those obtained in the shake-flask system. ALP activity has a substantial impact on the volatilization of crab shell particles, as shown by the results of several analytical techniques such as atomic absorption spectrometry, TGA, DSC, EDS, FTIR, and XRD.

Conclusions

We highlighted in the current study that the biovalorization of crab shell waste and the production of cost-effective ALP were being combined and that this was accomplished via the use of a new and innovative medium formulation design for seafood waste management as well as scaling up production of ALP on the bench-top scale.

A sustainable and effective bioprocessing approach for improvement of acid phosphatase production and rock phosphate solubilization by Bacillus haynesii strain ACP1

There is indeed a tremendous increase in biotechnological production on a global scale, more and more innovative bioprocesses, therefore, require to perform ideally not only in a small lab- but also on large production scales. Efficient microbial process optimization is a significant challenge when accomplishing a variety of sustainable development and bioengineering application objectives. In Egypt's mines, several distinct types of rock phosphate (RP) are utilized as a source of phosphate fertilizers in agriculture. It is more ecologically beneficial to utilize RP bio-solubilization than acidulation. Therefore, this work aimed to strategically scale up the acid phosphatase (ACP) production and RP bio-solubilization by the newly-discovered Bacillus haynesii. The use of consecutive statistical experimental approaches of Plackett-Burman Design (PBD), and Rotatable Central Composite Design (RCCD), followed by pH-uncontrolled cultivation conditions in a 7 L bench-top bioreactor revealed an innovative medium formulation. These approaches substantially improved ACP production, reaching 207.6 U L^-1 with an ACP yield coefficient Y_p/x of 25.2 and a specific growth rate (µ) of 0.07 h^-1. The metals Na, Li, and Mn were the most efficiently released from RP during the solubilization process by B. haynesii. The uncontrolled pH culture condition is the most suitable setting for simultaneously improving the ACP and organic acids production. The most abundant organic acid produced through the cultivation process was lactic acid, followed by glutamic acid and hydroxybenzoic acid isomer. The findings of TGA, DSC, SEM, EDS, FTIR, and XRD analysis emphasize the significant influence of organic acids and ACP activity on the solubilization of RP particles.

Biovalorization of raw agro-industrial waste through a bioprocess development platform for boosting alkaline phosphatase production by Lysinibacillus sp. strain APSO

This study highlighted the exploitation of mathematical models for optimizing the growth conditions that give the highest phosphatase productivity from a newfound Lysinibacillus sp. strain APSO isolated from a slime sample. Mathematical models facilitate data interpretation and provide a strategy to solve fermentation problems. Alkaline phosphatase (ALP) throughput was enhanced by 16.5-fold compared to basal medium based on a sequential optimization strategy that depended on two-level Plackett–Burman design and central composite design. The additional improvement for volumetric productivity and specific production yield was followed in a 7 L bench-top bioreactor to evaluate microbial growth kinetics under controlled and uncontrolled pH conditions. The pH-controlled batch cultivation condition neither supported cell growth nor enhanced ALP productivity. In contrast, the uncontrolled pH batch cultivation condition provided the highest ALP output (7119.4 U L⁻¹) and specific growth rate (µ = 0.188 h⁻¹) at 15 h from incubation time, which was augmented > 20.75-fold compared to the basal medium. To the authors’ knowledge, this study is the second report that deals with how to reduce the production cost of the ALP production process via utilization of agro-industrial waste, such as molasses and food waste (eggshell), as a nutrimental source for the improvement of the newfound Lysinibacillus sp. strain APSO ALP throughput.

Dynamic consolidated bioprocessing for innovative lab-scale production of bacterial alkaline phosphatase from Bacillus paralicheniformis strain APSO

To meet the present and forecasted market demand, bacterial alkaline phosphatase (ALP) production must be increased through innovative and efficient production strategies. Using sugarcane molasses and biogenic apatite as low-cost and easily available raw materials, this work demonstrates the scalability of ALP production from a newfound Bacillus paralicheniformis strain APSO isolated from a black liquor sample. Mathematical experimental designs including sequential Plackett–Burman followed by rotatable central composite designs were employed to select and optimize the concentrations of the statistically significant media components, which were determined to be molasses, (NH₄)₂NO₃, and KCl. Batch cultivation in a 7-L stirred-tank bioreactor under uncontrolled pH conditions using the optimized medium resulted in a significant increase in both the volumetric and specific productivities of ALP; the alkaline phosphatase throughput 6650.9 U L⁻¹, and µ = 0.0943 h⁻¹; respectively, were obtained after 8 h that, ameliorated more than 20.96, 70.12 and 94 folds compared to basal media, PBD, and RCCD; respectively. However, neither the increased cell growth nor enhanced productivity of ALP was present under the pH-controlled batch cultivation. Overall, this work presents novel strategies for the statistical optimization and scaling up of bacterial ALP production using biogenic apatite.

Effect of nutrient limitation on biofilm formation and phosphatase activity of a Citrobacter sp

A phosphatase-overproducing Citrobacter sp. (NCIMB 40259) was grown in an air-lift reactor in steady-state continuous culture under limitation of carbon, phosphorus or nitrogen. Substantial biofilm formation, and the highest phosphatase activity, were observed under lactose limitation. However, the total amount of biofilm wet biomass and the phosphatase specific activity were reduced in phosphorus- or nitrogen-limited cultures or when glucose was substituted for lactose as the limiting carbon source. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) showed differences in cell and biofilm morphology in relation to medium composition. Electron microscopy suggested that the differences in biofilm formation may relate to differential expression of fimbriae on the cell surface.

Localization of enzymically enhanced heavy metal accumulation by Citrobacter sp. and metal accumulation in vitro by liposomes containing entrapped enzyme

A heavy-metal-accumulating Citrobacter sp. has been used for the treatment of metal-laden industrial wastes. Metal uptake is mediated via a cell-bound phosphatase that liberates inorganic phosphate which precipitates with heavy metals as cell-bound metal phosphate. A phosphatase-efficient mutant accumulated little UO(2)2+, while a phosphatase-overproducing mutant accumulated correspondingly more metal, with a uranium loading equivalent to the bacterial dry weight achieved after 6 h exposure of resting cells to uranyl ion in the presence of phosphatase substrate (glycerol 2-phosphate). The phosphatase, visualized by immunogold labelling in the parent and overproducing strains, but not seen in the deficient mutant, was held within the periplasmic space with, in some cells, a higher concentration at the polar regions. Enzyme was also associated with the outer membrane and found extracellularly. Accumulated uranyl phosphate was visible as cell-surface- and polar-localized deposits, identified by energy-dispersive X-ray analysis (EDAX), proton-induced X-ray emission analysis (PIXE) and X-ray diffraction analysis (XRD) as polycrystalline HUO2PO4.4H2O. Nucleation sites for initiation of biocrystallization were identified at the cytoplasmic and outer membranes, prompting consideration of an in vitro biocatalytic system for metal waste remediation. Phosphatidylcholine-based liposomes with entrapped phosphatase released phosphate comparably to whole cells, as shown by 31P NMR spectroscopy in the presence of 'NMR-silent' 112Cd2+. Application of liposome-immobilized enzyme to the decontamination of uranyl solutions was, however, limited by rapid fouling of the biocatalyst by deposited uranyl phosphate. It is suggested that the architecture of the bacterial cell surface provides a means of access of uranyl ion to the inner and outer membranes and enzymically liberated phosphate in a way that minimizes fouling in whole cells.

Enzymically accelerated biomineralization of heavy metals: application to the removal of americium and plutonium from aqueous flows

A biological process for the removal of heavy metals from the aqueous flows is described. Metals are precipitated on the surface of immobilized cells of a Citrobacter sp. as cell-bound metal phosphates. This uses phosphate liberated by the activity of a cell-bound phosphatase. Some radionuclides (e.g. 241americium) form metal phosphates readily; efficient removal of 241Am on a continuous basis is demonstrated. At low phosphatase activities, the efficiency of uranium removal correlates with enzyme activity. High phosphatase activities are not realised as an increase in metal removal, suggesting that chemical events become rate-limiting. Studies have suggested that maximal metal uptake occurs only after nucleation and the formation of precipitation foci. A model is presented to illustrate how nucleation and crystallization processes could enhance the removal of plutonium and neptunium from dilute solutions.