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Background: Bacteriocin-like inhibitory substance (BLIS) demonstrates potent inhibitory effect against oral pathogens. To apply in oral care products, high purity of BLIS is required in view of the safety and effectiveness in the application. Therefore, aqueous two-phase systems (ATPS) are introduced for the recovery and purification of BLIS. Methods: The optimization of ionic liquid-based ATPS (ILATPS) for the purification of BLIS from Enterococcus faecium CC2 was performed using response surface methodology (RSM). The partially purified BLIS was then identified, and the inhibitory effect against Streptococcus mutans UKMCC1019 was assessed. Significant Findings: ILATPS with a pH of 7 at a temperature of 40 °C, comprising of 10 % (w/w) fermentation broth, 15 % (w/w) 1‑butyl‑3-methylimidazolium tetrafluoroborate, (Bmim)BF4, 12.5 % (w/w) sodium citrate and 3 % (w/w) sodium chloride, resulted in the optimum purification factor of 4.406, recovery yield of 67.213 % and partition coefficient of 4.852. The BLIS was identified as enterocin CC2, with a molecular size of approximately 5.5–6 kDa. Furthermore, the partially purified BLIS at a concentration of 1.00 mg/mL demonstrated effective growth inhibition against S. mutans UKMCC1019. The ILATPS was shown to be a potential technology to enhance the purity of BLIS from E. faecium CC2.

Saccharomyces cerevisiae is being used for long as a rich source of proteins, sugars, nucleotides, vitamins, and minerals. Yeast lysates from autolyzed and hydrolyzed yeast cells have found numerous applications in the food industry. This study explored the feasibility of producing yeast lysates using an enzymolysis approach and proposed an ultrasonic-assisted enzymolysis process to realize yeast extract production with high total soluble solids. The efficiency of each process was compared and evaluated based on total soluble solids (Brix), protein content (mg/mL), cell viability (log CFU/mL), dry weight of yeast extract (mg/mL), and dry weight of cell wall (mg/mL). Results indicated that the total soluble solids and dry weight of yeast extract were higher using ultrasonic-assisted enzymolysis compared to those of autolysis and enzymolysis treatments. The ultrasonic-assisted enzymolysis parameters consisted of 0.1 Alcalase with 50 power, 80 pulse after 30 min, completely attenuated S. cerevisiae cells, and yielded the highest yeast extract and cell wall. A total of 9.62 ( w/w) of beta-glucan in the yeast extract was obtained through this process. This study for the first time explored the feasibility of utilizing the peptidase with the assistance of ultrasonication to produce Baker’s yeast extract and use it as a food supplement. In addition, the cell wall from the lysis treatment can be used as an agent for microencapsulating probiotics. © 2024, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

In eukaryotes, serine proteases are cellular localized hydrolases reported to regulate essential biological reactions. Improved industrial applications of proteins are aided by prediction and analysis of their 3-dimensional structures (3D). A serine protease was identified from CTG-clade yeast Meyerozyma guilliermondii strain SO and its 3D structure as well as its catalytic attributes have not been fully understood yet, thus we seek to report on the catalytic mechanism of M. guilliermondii strain SO MgPRB1 using substrate PMSF via in silico docking as well as its stability by way of disulfide bonds formation. Herein, bioinformatics tools and techniques were used to predict, validate and analyze the possible changes of CUG ambiguity (if any) in strain SO using template PDB ID: 3F7O. Structural assessments confirmed the classic catalytic triad Asp305, His337, and Ser499. Superimposition of MgPRB1 and template 3F7O structures revealed the unlinked cysteine residues between Cys341, Cys440, Cys471 and Cys506 of MgPRB1 compared to template 3F7O with two disulfide bonds formation, which confers structural stability. In conclusion, serine protease structure from strain SO was successfully predicted and studies towards understanding at the molecular level may be undertaken for its potential applications in the degradation of peptide bonds.

Pasteurella spp. are Gram-negative facultative bacteria that cause severe economic and animal losses. Pasteurella-based vaccines are the most promising solution for controlling Pasteurella spp. outbreaks. Remarkably, insufficient biomass cultivation (low cell viability and productivity) and lack of knowledge about the cultivation process have impacted the bulk production of animal vaccines. Bioprocess optimization in the shake flask and bioreactor is required to improve process efficiency while lowering production costs. However, its state of the art is limited in providing insights on its biomass upscaling, preventing a cost-effective vaccine with mass-produced bacteria from being developed. In general, in the optimum cultivation of Pasteurella spp., production factors such as pH (6.0–8.2), agitation speed (90–500 rpm), and temperature (35–40 °C) are used to improve production yield. Hence, this review discusses the production strategy of Pasteurella and Mannheimia species that can potentially be used in the vaccines for controlling pasteurellosis. The physicochemical factors related to operational parameter process conditions from a bioprocess engineering perspective that maximize yields with minimized production cost are also covered, with the expectation of facilitating the commercialization process.

Cancer remains one of the key causes of mortality globally, in spite of the availability of advanced detection and treatment strategies. Conventional cancer therapies have non-selectivity to the target cells. Secondly, conventional cancer therapies are proved to cause various side effects during the treatment. Lastly, cancer cells are known to develop resistance to the currently available therapies. Therefore, there is a demand for a novel therapy for various types of cancer. Some of the bacteriocins have been reported to have an anti-cancer effect against various types of cancer cells. Bacteriocins are proteins synthesized by bacterial ribosomes. They have shown high selectivity toward the cancer cells and low cytotoxicity toward normal cells. This makes them a promising anticancer candidate to replace or combine with conventional therapeutic agents. In this review, the latest studies on the selectivity of bacteriocins against cancer cells and their anticancer activities in preclinical and clinical studies will be discussed.

This study was aimed at evaluating the influence of type and concentration of lyoprotectants, storage temperature and storage duration on cell viability and antibacterial activity of Lactococcus lactis Gh1 after drying and during a long-term storage for 120 days. Highest survivability rate after freeze-drying was observed for cells protected in galactose followed by trehalose and peptone. The differences in cell viability among the different types of protective agent and between the concentrations after freeze-drying were not significant. However, significant difference was seen between the protective agents at different concentrations during storage. At high storage temperatures, the number of viable cells decreased for all protective agents and concentrations investigated in this study. Antibacterial activity from L. lactis Gh1 against Listeria monocytogenes ATCC 15313 was in linear correlation with the viable cell counts. Possible formulation of protective agent from this study could be applied in the industrial development of probiotic and bioprotective cultures.

Calcium carbonate precipitation is a form of sedimentary carbonate which occurs naturally in an ecosystem saturated with calcium ions and prompted by a wide assortment of microorganisms through various biological processes. The phenomenon, also known as “Microbially Induced Calcium Carbonate Precipitation” (MICP), may find the characteristics of its by-product biomineral to be a promising alternative for conventional cement. Several microalgae species can produce cementitious CaCO3 deposits, which are permanently removed as solid crystal upon achieving suitable conditions for precipitation. This study assessed a total of eight microalgae for their biomineralization capability in calcification media containing 12 mM of calcium chloride dihydrate and 0.18 to 5.0 mM of sodium bicarbonate by analyzing the profiles of cell growth, pH, calcium and bicarbonate ions concentration, alkalinity, and saturation index. Among the microalgae tested, Synechocystis sp. ATCC 27178 cultured in BG-11 medium with 5.0 mM of NaHCO3 had shown the highest calcium ions removal rate (0.70 mM/day), followed by Chlorella vulgaris (0.40 mM/day). The morphology of CaCO3 crystals precipitated from these microalgae was analyzed via scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX). The elucidation of the crystal polymorph as calcite was then confirmed through X-ray diffraction analysis.

Haematococcus lacustris (formerly called Haematococcus pluvialis) is regarded as the most promising microalgae for the production of natural astaxanthin, which is secondary metabolism used as a dietary supplement, also for cosmetic applications, due to its high anti-oxidant activity. Astaxanthin has a wide range of biological activities and high economic potential, and currently dominates the market in its synthetic form. Furthermore, because of the difficulty of bioprocess and the high cost of cultivation, astaxanthin extracted from this microalga is still expensive due to its low biomass and pigment productivities. Large-scale biomass production in biotechnological production necessitates the processing of a large number of cultures as well as the use of both indoor and outdoor systems, such as open pond raceway systems and photo-bioreactors (PBR). The photo-bioreactors systems are suitable for mass production because growth conditions can be controlled, and the risk of contamination can be reduced to a certain extent and under specific culture parameters. This review discusses current technologies being developed to improve cultivation and operation efficiency and profitability, as well as the effect of parameter factors associated with H. lacustris cultivation on biomass and astaxanthin bioproduction, and even strategies for increasing bioproduction and market potential for H. lacustris astaxanthin.

Purpose Okara is a highly perishable food processing by-product from soymilk and tofu manufacture. The present study aimed to optimize the pre-treatment of okara on the extraction of reducing sugars by applying a multi-enzyme complex, Viscozyme, containing a variety of carbohydrases to hydrolyze the okara cell walls. The chemical composition and the morphological structure of enzymatic-treated okara (ETO) were scrutinized. Methods Enzymatic hydrolysis pre-treatment was carried out under different enzyme concentrations (5–8%), temperatures (50–60 °C) and pH values (3–4) according to a central composite rotatable design, in which the ranges were chosen based on preliminary study. Results The optimal conditions for maximum reducing sugars extraction (4.78 mg/mL) were 8.0% (w/w) of enzyme, 50 °C and pH 3.0 for 4 h hydrolysis time, representing a 158.33 times increment, compared to the sample without enzymatic pre-treatment. The chromatogram from high performance liquid chromatography (HPLC) revealed that the carbohydrates such as glucose, fructose, raffinose and stachyose increased after hydrolysis. Surprisingly, arabinose which was not detected in raw okara (RO) was present in ETO. Scanning electron microscopy (SEM) confirmed the highly structured matrix of okara was unfolded and broken by the action of enzyme pre-treatment while energy-dispersive X-ray spectroscopy (EDS) imparted the changes of elemental components in ETO. The ETO showed higher antioxidant capacity than the control by DPPH, ABTS and FRAP tests. Conclusion Enzymatic hydrolysis proved to be an efficient way to enhance the physicochemical properties of okara for possible uses, making this residue into a newly added value product.

As the most recognizable natural secondary carotenoid astaxanthin producer, the green microalga Haematococcus pluvialis cultivation is performed via a two-stage process. The first is dedicated to biomass accumulation under growth-favoring conditions (green stage), and the second stage is for astaxanthin evolution under various stress conditions (red stage). This mini-review discusses the further improvement made on astaxanthin production by providing an overview of recent works on H. pluvialis, including the valuable ideas for bioprocess optimization on cell growth, and the current stress-exerting strategies for astaxanthin pigment production. The effects of nutrient constituents, especially nitrogen and carbon sources, and illumination intensity are emphasized during the green stage. On the other hand, the significance of the nitrogen depletion strategy and other exogenous factors comprising salinity, illumination, and temperature are considered for the astaxanthin inducement during the red stage. In short, any factor that interferes with the cellular processes that limit the growth or photosynthesis in the green stage could trigger the encystment process and astaxanthin formation during the red stage. This review provides an insight regarding the parameters involved in bioprocess optimization for high-value astaxanthin biosynthesis from H. pluvialis.

Bacteriocin-like inhibitory substances (BLIS) produced by Lactococcus lactis Gh1 had shown antimicrobial activity against Listeria monocytogenes ATCC 15313. Brain Heart Infusion (BHI) broth is used for the cultivation and enumeration of lactic acid bacteria, but there is a need to improve the current medium composition for enhancement of BLIS production, and one of the approaches is to model the optimization process and identify the most appropriate medium formulation. Response surface methodology (RSM) and artificial neural network (ANN) models were employed in this study. In medium optimization, ANN (R2 = 0.98) methodology provided better estimation point and data fitting as compared to RSM (R2 = 0.79). In ANN, the optimal medium consisted of 35.38 g/L soytone, 16 g/L fructose, 3.25 g/L sodium chloride (NaCl) and 5.40 g/L disodium phosphate (Na2HPO4). BLIS production in optimal medium (717.13 ± 0.76 AU/mL) was about 1.40-fold higher than that obtained in nonoptimised (520.56 ± 3.37 AU/mL) medium. BLIS production was further improved by about 1.18 times higher in 2 L stirred tank bioreactor (787.40 ± 1.30 AU/mL) as compared to that obtained in 250 mL shake flask (665.28 ± 14.22 AU/mL) using the optimised medium.

Growth of mutant gdhA Pasteurella multocida B:2 was inhibited by the accumulation of a by-product, namely ammonium in the culture medium during fermentation. The removal of this by-product during the cultivation of mutant gdhA P. multocida B:2 in a 2 L stirred-tank bioreactor integrated with an internal column using cation-exchange adsorption resin for the improvement of cell viability was studied. Different types of bioreactor system (dispersed and internal) with resins were successfully used for ammonium removal at different agitation speeds. The cultivation in a bioreactor integrated with an internal column demonstrated a significant improvement in growth performance of mutant gdhA P. multocida B:2 (1.05 × 1011 cfu/mL), which was 1.6-fold and 8.4-fold as compared to cultivation with dispersed resin (7.2 × 1010 cfu/mL) and cultivation without resin (1.25 × 1010 cfu/mL), respectively. The accumulation of ammonium in culture medium without resin (801 mg/L) was 1.24-fold and 1.37-fold higher than culture with dispersed resin (642.50 mg/L) and culture in the bioreactor integrated with internal adsorption (586.50 mg/L), respectively. Results from this study demonstrated that cultivation in a bioreactor integrated with the internal adsorption column in order to remove ammonium could reduce the inhibitory effect of this by-product and improve the growth performance of mutant gdhA P. multocida B:2.

The biosynthesis of calcium carbonate (CaCO3) minerals through a metabolic process known as microbially induced calcium carbonate precipitation (MICP) between diverse microorganisms, and organic/inorganic compounds within their immediate microenvironment, gives rise to a cementitious biomaterial that may emerge as a promissory alternative to conventional cement. Among photosynthetic microalgae, Chlorella vulgaris has been identified as one of the species capable of undergoing such activity in nature. In this study, response surface technique was employed to ascertain the optimum condition for the enhancement of biomass and CaCO3 precipitation of C. vulgaris when cultured in Blue-Green (BG)-11 aquaculture medium. Preliminary screening via Plackett–Burman Design showed that sodium nitrate (NaNO3), sodium acetate, and urea have a significant effect on both target responses (p < 0.05). Further refinement was conducted using Box–Behnken Design based on these three factors. The highest production of 1.517 g/L C. vulgaris biomass and 1.143 g/L of CaCO3 precipitates was achieved with a final recipe comprising of 8.74 mM of NaNO3, 61.40 mM of sodium acetate and 0.143 g/L of urea, respectively. Moreover, polymorphism analyses on the collected minerals through morphological examination via scanning electron microscopy and crystallographic elucidation by X-ray diffraction indicated to predominantly calcite crystalline structure.

Pasteurella multocida serotype B:2 is the causative agent of haemorrhagic septicaemia, a fatal disease in cattle and buffaloes. For use as a vaccine in the treatment of HS disease, an efficient cultivation of attenuated gdhA derivative P. multocida B:2 (mutant) for mass production of viable cells is required. In this study, the role of amino acids and vitamins on the growth of this particular bacterium was investigated. Initially, three basal media (Brain–heart infusion, Terrific broth, and defined medium YDB) were assessed in terms of growth performance of P. multocida B:2. YDB medium was selected and redesigned to take into account the effects of amino acids (glutamic acid, cysteine, glycine, methionine, lysine, tyrosine, and histidine) and vitamins (vitamin B1, nicotinic acid, riboflavin, pyridoxine, pantothenic acid, and biotin). High viable cell number was largely affected by the availability of micronutrient components and macronutrients. Histidine was essential for the growth whereby a traceable amount (20 mM) was found to greatly enhance the growth of gdhA derivative P. multocida B:2 mutant (6.6 × 109 cfu/mL) by about 19 times as compared to control culture (3.5 × 108 cfu/mL). In addition, amongst the vitamins added, riboflavin exhibited the highest impact on the viability of gdhA derivative P. multocida B:2 mutant (5.3 × 109 cfu/mL). Though the combined histidine and riboflavin in the culture eventually did not promote the stacking impact on cell growth and cell viability, nonetheless, they were still essential and important in either growth medium or production medium.

The bulk availability of banana waste in the world has made a move towards the development of alternative novel renewable sugars in present study as the pressed juice from banana frond and pseudostem was found to contain high level of renewable sugars such as glucose, sucrose and fructose. By using a simple sugarcane press, the glucose content in the banana frond juice was 16.6 g/L, which accounts for 55% of the total fermentable sugars. From the results, the lipase production reached ∼200 U/mL in medium comprising banana frond juice and banana pseudostem juice, comparable to basal medium with glucose (206.3 U/mL) as carbon source in basal media. As banana pseudostem possesses high content of starch, microwave heating pretreatment showed 36% enhancement of glucose content (10.4 g/L) in juice as compared to direct pressed juice (7.78 g/L). This result indicates that banana waste juice can be used as an alternative fermentable carbon source for lipase production and has potential as a fermentable carbon source.