Displaying publications 1 - 20 of 464 in total

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  1. Azizan KA, Ressom HW, Mendoza ER, Baharum SN
    PeerJ, 2017;5:e3451.
    PMID: 28695065 DOI: 10.7717/peerj.3451
    Lactococcus lactis subsp. cremoris MG1363 is an important starter culture for dairy fermentation. During industrial fermentations, L. lactis is constantly exposed to stresses that affect the growth and performance of the bacterium. Although the response of L. lactis to several stresses has been described, the adaptation mechanisms at the level of in vivo fluxes have seldom been described. To gain insights into cellular metabolism, 13C metabolic flux analysis and gas chromatography mass spectrometry (GC-MS) were used to measure the flux ratios of active pathways in the central metabolism of L. lactis when subjected to three conditions varying in temperature (30°C, 37°C) and agitation (with and without agitation at 150 rpm). Collectively, the concentrations of proteinogenic amino acids (PAAs) and free fatty acids (FAAs) were compared, and Pearson correlation analysis (r) was calculated to measure the pairwise relationship between PAAs. Branched chain and aromatic amino acids, threonine, serine, lysine and histidine were correlated strongly, suggesting changes in flux regulation in glycolysis, the pentose phosphate (PP) pathway, malic enzyme and anaplerotic reaction catalysed by pyruvate carboxylase (pycA). Flux ratio analysis revealed that glucose was mainly converted by glycolysis, highlighting the stability of L. lactis' central carbon metabolism despite different conditions. Higher flux ratios through oxaloacetate (OAA) from pyruvate (PYR) reaction in all conditions suggested the activation of pyruvate carboxylate (pycA) in L. lactis, in response to acid stress during exponential phase. Subsequently, more significant flux ratio differences were seen through the oxidative and non-oxidative pentose phosphate (PP) pathways, malic enzyme, and serine and C1 metabolism, suggesting NADPH requirements in response to environmental stimuli. These reactions could play an important role in optimization strategies for metabolic engineering in L. lactis. Overall, the integration of systematic analysis of amino acids and flux ratio analysis provides a systems-level understanding of how L. lactis regulates central metabolism under various conditions.
    Matched MeSH terms: Fermentation
  2. Lee BQ, Khor SM
    Compr Rev Food Sci Food Saf, 2015 Jan;14(1):48-66.
    PMID: 33401813 DOI: 10.1111/1541-4337.12120
    Soy sauce, a dark-colored seasoning, is added to enhance the sensory properties of foods. Soy sauce can be consumed as a condiment or added during the preparation of food. There are 3 types of soy sauce: fermented, acid-hydrolyzed vegetable protein (acid- HVP), and mixtures of these. 3-Chloropropane-1,2-diol (3-MCPD) is a heat-produced contaminants formed during the preparation of soy sauce and was found to be a by-product of acid-HVP-produced soy sauce in 1978. 3-MCPD has been reported to be carcinogenic, nephrotoxic, and reproductively toxic in laboratory animal testing and has been registered as a chemosterilant for rodent control. 3-MCPD is classified as a possible carcinogenic compound, and the maximum tolerated limit in food has been established at both national and international levels. The purpose of this review is to provide an overview on the detection of 3-MCPD in soy sauce, its toxic effects, and the potential methods to reduce its concentration, especially during the production of acid-HVP soy sauce. The methods of quantification are also critically reviewed with a focus on efficiency, suitability, and challenges encountered in analysis.
    Matched MeSH terms: Fermentation
  3. Batool T, Makky EA, Jalal M, Yusoff MM
    Appl Biochem Biotechnol, 2016 Mar;178(5):900-23.
    PMID: 26547852 DOI: 10.1007/s12010-015-1917-3
    L-asparaginase (LA) catalyzes the degradation of asparagine, an essential amino acid for leukemic cells, into ammonia and aspartate. Owing to its ability to inhibit protein biosynthesis in lymphoblasts, LA is used to treat acute lymphoblastic leukemia (ALL). Different isozymes of this enzyme have been isolated from a wide range of organisms, including plants and terrestrial and marine microorganisms. Pieces of information about the three-dimensional structure of L-asparaginase from Escherichia coli and Erwinia sp. have identified residues that are essential for catalytic activity. This review catalogues the major sources of L-asparaginase, the methods of its production through the solid state (SSF) and submerged (SmF) fermentation, purification, and characterization as well as its biological roles. In the same breath, this article explores both the past and present applications of this important enzyme and discusses its future prospects.
    Matched MeSH terms: Fermentation
  4. Zentou H, Zainal Abidin Z, Yunus R, Awang Biak DR, Abdullah Issa M, Yahaya Pudza M
    ACS Omega, 2021 Feb 16;6(6):4137-4146.
    PMID: 33644536 DOI: 10.1021/acsomega.0c04025
    Despite the advantages of continuous fermentation whereby ethanol is selectively removed from the fermenting broth to reduce the end-product inhibition, this process can concentrate minor secondary products to the point where they become toxic to the yeast. This study aims to develop a new mathematical model do describe the inhibitory effect of byproducts on alcoholic fermentation including glycerol, lactic acid, acetic acid, and succinic acid, which were reported as major byproducts during batch alcoholic fermentation. The accumulation of these byproducts during the different stages of batch fermentation has been quantified. The yields of total byproducts, glycerol, acetic acid, and succinic acid per gram of glucose were 0.0442, 0.023, 0.0155, and 0.0054, respectively. It was found that the concentration of these byproducts linearly increases with the increase in glucose concentration in the range of 25-250 g/L. The results have also showed that byproduct concentration has a significant inhibitory effect on specific growth coefficient (μ) whereas no effect was observed on the half-velocity constant (Ks). A new mathematical model of alcoholic fermentation was developed considering the byproduct inhibitory effect, which showed a good performance and more accuracy compared to the classical Monod model.
    Matched MeSH terms: Fermentation
  5. Sivagurunathan P, Kuppam C, Mudhoo A, Saratale GD, Kadier A, Zhen G, et al.
    Crit Rev Biotechnol, 2018 Sep;38(6):868-882.
    PMID: 29264932 DOI: 10.1080/07388551.2017.1416578
    This review provides the alternative routes towards the valorization of dark H2 fermentation effluents that are mainly rich in volatile fatty acids such as acetate and butyrate. Various enhancement and alternative routes such as photo fermentation, anaerobic digestion, utilization of microbial electrochemical systems, and algal system towards the generation of bioenergy and electricity and also for efficient organic matter utilization are highlighted. What is more, various integration schemes and two-stage fermentation for the possible scale up are reviewed. Moreover, recent progress for enhanced performance towards waste stabilization and overall utilization of useful and higher COD present in the organic source into value-added products are extensively discussed.
    Matched MeSH terms: Fermentation
  6. Zareian M, Ebrahimpour A, Bakar FA, Mohamed AK, Forghani B, Ab-Kadir MS, et al.
    Int J Mol Sci, 2012;13(5):5482-97.
    PMID: 22754309 DOI: 10.3390/ijms13055482
    l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound.
    Matched MeSH terms: Fermentation
  7. Yap AC, Chan KG, Sim KS, Choo YM
    Nat Prod Res, 2016 Apr;30(7):783-8.
    PMID: 26252083 DOI: 10.1080/14786419.2015.1065492
    Enterobacter cloacae is a highly pathogenic Gram-negative proteobacterium which is responsible for a wide array of infections. In the present study, the fermentation culture of E. cloacae has yielded one new oxolane compound, Rimboxo (1) in addition to three known compounds, i.e. Maculosine (2), phenylacetic acid (3) and methyl myristate (4). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.
    Matched MeSH terms: Fermentation
  8. Noroul Asyikeen, Z., Ma’aruf, A.G., Sahilah, A.M., Mohd. Khan, A., Wan Aida, W.M.
    MyJurnal
    Megabiodiversity of Malaysian’s flora and fauna which include microorganism could be conserved and served as alternative source indigenous yeast, the leavening agent of commercial bread making. This study was conducted in attempt to exploit the potential of Saccharomyces cerevisiae strains isolated from 30 different local fruits and plant parts as a leavening agent in bread making. The enrichment was carried out by fermenting the plant samples in medium containing Grape Must at 25°C for 10 days following by isolation of tentative yeasts at 30°C for 3 to 5 days. 20 out of 30 samples tested showed the presence of yeasts was then selected for identification of S. cerevisiae strains through biochemical and physiological tests. Of the 20 yeast strains examined, 13 strains were identified as S. cerevisiae and potentially used as leavening agent in bread making where 5 strains namely SN3, SMK9, SDB10, SRB11 and SS12 showed better fermentative performance compared to commercial strains. Thus, indicated that the local fruits and plant parts could be the potential source of indigenous S. cerevisiae strains for leavening agent in bread making.
    Matched MeSH terms: Fermentation
  9. Ong SY, Zainab-L I, Pyary S, Sudesh K
    Appl Microbiol Biotechnol, 2018 Mar;102(5):2117-2127.
    PMID: 29404644 DOI: 10.1007/s00253-018-8788-9
    Polyhydroxyalkanoate (PHA) is a family of microbial polyesters that is completely biodegradable and possesses the mechanical and thermal properties of some commonly used petrochemical-based plastics. Therefore, PHA is attractive as a biodegradable thermoplastic. It has always been a challenge to commercialize PHA due to the high cost involved in the biosynthesis of PHA via bacterial fermentation and the subsequent purification of the synthesized PHA from bacterial cells. Innovative enterprise by researchers from various disciplines over several decades successfully reduced the cost of PHA production through the efficient use of cheap and renewable feedstock, precisely controlled fermentation process, and customized bacterial strains. Despite the fact that PHA yields have been improved tremendously, the recovery and purification processes of PHA from bacterial cells remain exhaustive and require large amounts of water and high energy input besides some chemicals. In addition, the residual cell biomass ends up as waste that needs to be treated. We have found that some animals can readily feed on the dried bacterial cells that contain PHA granules. The digestive system of the animals is able to assimilate the bacterial cells but not the PHA granules which are excreted in the form of fecal pellets, thus resulting in partial recovery and purification of PHA. In this mini-review, we will discuss this new concept of biological recovery, the selection of the animal model for biological recovery, and the properties and possible applications of the biologically recovered PHA.
    Matched MeSH terms: Fermentation
  10. Rafiqul, I.S.M., Mimi Sakinah, A.M.
    MyJurnal
    Xylitol is a high value sugar alcohol with anticariogenic properties that is used as an ideal sweetener for diabetic patients. Industrially, xylitol is manufactured by catalytic reduction of pure xylose, which has
    some disadvantages. The fermentation process has been studied as an alternative, but its viability is dependent on the optimization of several variables. This fermentation process on an industrial-scale is not feasible due to decreased productivity. Compared to the fermentation process, enzymatic method is expected to make a substantial increase in productivity. Enzymatic xylitol production from xylose exist in lignocellulosics is an attractive and promising alternative method to the chemical process. The enzymatic method might be able to overcome the disadvantages of the chemical process. This article reviews the literature on the processes for xylitol production and identifies further ways for improved xylitol production to compete with the current chemical process.
    Matched MeSH terms: Fermentation
  11. Choi EM, Kim YH
    Food Chem Toxicol, 2008 Jan;46(1):375-9.
    PMID: 17904263 DOI: 10.1016/j.fct.2007.08.018
    The present study was undertaken to determine whether Ligularia fischeri leaf extract (LF) is efficacious against collagen-induced arthritis (CIA) in mice. DBA/1J mice were immunized with bovine type II collagen and treated with LF (100 and 200 mg/kg) for 49 days. Mice were assessed regularly for signs of arthritis and the levels of rheumatoid factor, anti-type II collagen antibody, cytokines, AST, ALT, and creatinine in serum were also examined after the animals were killed. The arthritis score and paw edema were markedly suppressed in the groups treated with LF. Moreover, levels of rheumatoid factor, anti-type II collagen antibody, tumor necrosis factor-alpha, interleukin (IL)-1, and IL-6 in sera were reduced by LF administration. These data suggest that L. fischeri might be effective for the treatment of inflammatory arthritis like human rheumatoid arthritis.
    Matched MeSH terms: Fermentation
  12. Ooi MF, Foo HL, Loh TC, Mohamad R, Rahim RA, Ariff A
    Sci Rep, 2021 Apr 07;11(1):7617.
    PMID: 33828119 DOI: 10.1038/s41598-021-87081-6
    Postbiotic RS5, produced by Lactiplantibacillus plantarum RS5, has been identified as a promising alternative feed supplement for various livestock. This study aimed to lower the production cost by enhancing the antimicrobial activity of the postbiotic RS5 by improving the culture density of L. plantarum RS5 and reducing the cost of growth medium. A combination of conventional and statistical-based approaches (Fractional Factorial Design and Central Composite Design of Response Surface Methodology) was employed to develop a refined medium for the enhancement of the antimicrobial activity of postbiotic RS5. A refined medium containing 20 g/L of glucose, 27.84 g/L of yeast extract, 5.75 g/L of sodium acetate, 1.12 g/L of Tween 80 and 0.05 g/L of manganese sulphate enhanced the antimicrobial activity of postbiotic RS5 by 108%. The cost of the production medium was reduced by 85% as compared to the commercially available de Man, Rogosa and Sharpe medium that is typically used for Lactobacillus cultivation. Hence, the refined medium has made the postbiotic RS5 more feasible and cost-effective to be adopted as a feed supplement for various livestock industries.
    Matched MeSH terms: Fermentation
  13. Chien Bong CP, Alam MNHZ, Samsudin SA, Jamaluddin J, Adrus N, Mohd Yusof AH, et al.
    J Environ Manage, 2021 Nov 15;298:113461.
    PMID: 34435568 DOI: 10.1016/j.jenvman.2021.113461
    Polyhydroxyalkanoate (PHA) is a type of polyesters produced in the form of accumulated intracellular granules by many microorganisms. It is viewed as an environmentally friendly bioproduct due to its biodegradability and biocompatibility. The production of the PHA using oil substrates such as waste oil and plant oil, has gained considerable attention due to the high product yield and lower substrate cost. Nevertheless, the PHA fermentation using oil substrate is complicated due to the heterogenous fatty acid composition, varied bio-accessibility and possible inhibitory effect on the bacterial culture. This review presents the current state-of-the-art of PHA production from oil-based substrates. This paper firstly discusses the technical details, such as the choice of bacteria strain and fermentation conditions, characteristic of the oil substrate as well as the PHA composition and application. Finally, the paper discusses the challenges and prospects for up-scaling towards a cleaner and effective bioprocess. From the literature review, depending on the cell culture and the type of PHA produced, the oil platform can have a PHA yield of 0.2-0.8 g PHA/g oil substrate, with PHA content mostly from 40 to 90% of the cell dry weight. There is an on-going search for more effective oil-utilising PHA producers and lower cost substrate for effective PHA production. The final application of the PHA polymer influences the treatment needed during downstream processing and its economic performance. PHA with different compositions exhibits varied decomposition behaviour under different conditions, requiring further insight towards its management towards a sustainable circular economy.
    Matched MeSH terms: Fermentation
  14. Biglari N, Orita I, Fukui T, Sudesh K
    J Biotechnol, 2020 Jan 10;307:77-86.
    PMID: 31669355 DOI: 10.1016/j.jbiotec.2019.10.013
    This study investigates the effect of strategies on poly(3-hydroxybutyrate) [P(3HB)] production in bioreactor. In the production of P(3HB), urea and glucose feeding streams were developed to characterize the fed-batch culture conditions for new Cupriavidus necator NSDG-GG mutant. Feeding urea in repeated fed-batch stage (RFB-I) at 6, and 12 h in cultivation led to insignificant kinetic effect on the cell dry mass (CDM) and P(3HB) accumulation. Feeding glucose in repeated fed-batch stage (RFB-II) demonstrated that the incremental feeding approach of glucose after urea in fill-and-draw (F/D) mode at 24, 30, 36, 42, and 48 h in fermentation increased CDM and P(3HB) concentration. In the 1st cycle in RFB-II, the cumulative CDM reached the value of 26.22 g/L and then it increased with the successive repeated fed-batches to attain biomass of 145 g/L at the end of 5th cycle of RFB-II. The final cumulative P(3HB) concentration at the end of 5th cycle of RFB-II reached 111 g/L with the overall yield of 0.50 g P(3HB) g gluc- 1; the CDM productivity from the RFB-II cycles was in the range of 0.84-1.3 g/(L·h). The RFB-II of glucose in an increment mode produced nearly 2.2 times more increase in CDM and P(3HB) productivities compared to the decrement RFB-II mode. Repeated cultivation had also the advantage of avoiding extra time required for innoculum preparation, and sterilization of bioreactor during batch, thereby it increased the overall industrial importance of the process.
    Matched MeSH terms: Fermentation
  15. Ida Muryany, Ahmad Rohi Ghazali, Nor Fadilah Rajab, Hing HL, Ina-Salwany, Mohd Zamri Saad, et al.
    Sains Malaysiana, 2018;47:2391-2399.
    Bacterial adhesion to host cells is the most important probiotic character. However, the adhesion of probiotic should not
    affect the viability of the host cells. In this study, Lactobacillus plantarum strain L8, Lactobacillus plantarum strain L20
    and Lactobacillus pentosus strain S1 were tested for their cytotoxic effects through MTT assay and their ability to adhere
    and colonize on HT-29 and CCD-18Co intestinal cells as detected microscopically using light microscopy and Scanning
    Electron Microscopy (SEM). No cytotoxicity effects were observed on both intestinal cells following 24 h treatment with
    all Lactobacillus strains. Additionally, all strains demonstrated strong adhesive activity where more than 100 bacteria
    adhered to both intestinal cells although differences in the adhesion scores observed among different strains. The adhesion
    as observed via SEM showed an autoagreggative pattern and adhered as clusters on the surface of both intestinal cells.
    In conclusion, all three Lactobacillus strains are non-cytotoxic to both cells with strong adhesion ability on intestinal
    cells and this study also proved that Malaysian fermented fish are good source of probiotic bacteria.
    Matched MeSH terms: Fermentation
  16. Chilakamarry CR, Mimi Sakinah AM, Zularisam AW, Sirohi R, Khilji IA, Ahmad N, et al.
    Bioresour Technol, 2022 Jan;343:126065.
    PMID: 34624472 DOI: 10.1016/j.biortech.2021.126065
    The increase in solid waste has become a common problem and causes environmental pollution worldwide. A green approach to valorise solid waste for sustainable development is required. Agricultural residues are considered suitable for conversion into profitable products through solid-state fermentation (SSF). Agricultural wastes have high organic content that is used as potential substrates to produce value-added products through SSF. The importance of process variables used in solid-phase fermentation is described. The applications of SSF developed products in the food industry as flavouring agents, acidifiers, preservatives and flavour enhancers. SSF produces secondary metabolites and essential enzymes. Wastes from agricultural residues are used as bioremediation agents, biofuels and biocontrol agents through microbial processing. In this review paper, the value addition of agricultural wastes by SSF through green processing is discussed with the current knowledge on the scenarios, sustainability opportunities and future directions of a circular economy for solid waste utilisation.
    Matched MeSH terms: Fermentation
  17. Ho CW, Lazim A, Fazry S, Hussain Zaki UKH, Massa S, Lim SJ
    J Sci Food Agric, 2020 Feb;100(3):1012-1021.
    PMID: 31646636 DOI: 10.1002/jsfa.10103
    BACKGROUND: Wines are produced via the alcoholic fermentation of suitable substrates, usually sugar (sugar cane, grapes) and carbohydrates (wheat, grain). However, conventional alcoholic fermentation is limited by the inhibition of yeast by ethanol produced, usually at approximately 13-14%. Aside from that, soursop fruit is a very nutritious fruit, although it is highly perishable, and thus produces a lot of wastage. Therefore, the present study aimed to produce fermented soursop juice (soursop wine), using combination of two starter cultures, namely mushroom (Pleurotus pulmonarius) and yeast (Saccharomyces cerevisiae), as well as to determine the effects of fermentation on the physicochemical and antioxidant activities of fermented soursop juice. Optimisation of four factors (pH, temperature, time and culture ratio) using response surface methodology were performed to maximise ethanol production.

    RESULTS: The optimised values for alcoholic fermentation were pH 4.99, 28.29 °C, 131 h and a 0.42 culture ratio (42:58, P. pulmonarius mycelia:S. cerevisiae) with a predicted ethanol concentration of 22.25%. Through a verification test, soursop wine with 22.29 ± 0.52% ethanol was produced. The antioxidant activities (1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power) showed a significant (P 

    Matched MeSH terms: Fermentation
  18. Harun R, Yip JW, Thiruvenkadam S, Ghani WA, Cherrington T, Danquah MK
    Biotechnol J, 2014 Jan;9(1):73-86.
    PMID: 24227697 DOI: 10.1002/biot.201200353
    The continuous growth in global population and the ongoing development of countries such as China and India have contributed to a rapid increase in worldwide energy demand. Fossil fuels such as oil and gas are finite resources, and their current rate of consumption cannot be sustained. This, coupled with fossil fuels' role as pollutants and their contribution to global warming, has led to increased interest in alternative sources of energy production. Bioethanol, presently produced from energy crops, is one such promising alternative future energy source and much research is underway in optimizing its production. The economic and temporal constraints that crop feedstocks pose are the main downfalls in terms of the commercial viability of bioethanol production. As an alternative to crop feedstocks, significant research efforts have been put into utilizing algal biomass as a feedstock for bioethanol production. Whilst the overall process can vary, the conversion of biomass to bioethanol usually contains the following steps: (i) pretreatment of feedstock; (ii) hydrolysis; and (iii) fermentation of bioethanol. This paper reviews different technologies utilized in the pretreatment and fermentation steps, and critically assesses their applicability to bioethanol production from algal biomass. Two different established fermentation routes, single-stage fermentation and two-stage gasification/fermentation processes, are discussed. The viability of algal biomass as an alternative feedstock has been assessed adequately, and further research optimisation must be guided toward the development of cost-effective scalable methods to produce high bioethanol yield under optimum economy.
    Matched MeSH terms: Fermentation
  19. Khairul Azly Zahan, Norhayati Pa’e, Ida Idayu Muhamad
    Sains Malaysiana, 2016;45:393-400.
    Acetobacter xylinum strains are known as efficient producers of cellulose. A. xylinum is an obligate aerobic bacterium that has an oxygen-based metabolism. The dissolved oxygen (DO) concentration in a rotary discs reactor (RDR) is one of the most important factors that need to be observed during the cellulose synthesis by these bacteria. In this study, the effects of different discs rotation speed (5, 7, 9 and 12 rpm) and fermentation period (3, 4, 5 and 6 days) on the DO concentration and production of bacterial cellulose in a 10-L RDR were examined. The highest yield was obtained at 7 rpm with a total dried weight of 28.3 g for 4 days fermentation. The results showed that the DO concentration in the 10-L RDR increased in the range of 13 to 17% with increasing of discs rotation speed from 7 to 12 rpm. However, fermentation with high discs rotation speed at 12 rpm reduced the bacterial cellulose production. Analysis of data using Statistica 8.0 showed a high coefficient of determination value (R2 = 0.92). In conclusion, discs rotation speed gave more significant effect on the DO concentration and production of bacterial cellulose in 10-L RDR compared to fermentation period. This was further combined with synergistic effect from sufficient consumption of oxygen for the enhanced production of bacterial cellulose and providing the controlled environment for encouraging bacterial growth throughout the fermentation process.
    Matched MeSH terms: Fermentation
  20. Madihah MS, Ariff AB, Khalil MS, Suraini AA, Karim MI
    Folia Microbiol (Praha), 2001;46(3):197-204.
    PMID: 11702403
    A study of the kinetics and performance of solvent-yielding batch fermentation of individual sugars and their mixture derived from enzymic hydrolysis of sago starch by Clostridium acetobutylicum showed that the use of 30 g/L gelatinized sago starch as the sole carbon source produced 11.2 g/L total solvent, i.e. 1.5-2 times more than with pure maltose or glucose used as carbon sources. Enzymic pretreatment of gelatinized sago starch yielding maltose and glucose hydrolyzates prior to the fermentation did not improve solvent production as compared to direct fermentation of gelatinized sago starch. The solvent yield of direct gelatinized sago starch fermentation depended on the activity and stability of amylolytic enzymes produced during the fermentation. The pH optima for alpha-amylase and glucoamylase were found to be at 5.3 and 4.0-4.4, respectively. alpha-Amylase showed a broad pH stability profile, retaining more than 80% of its maximum activity at pH 3.0-8.0 after a 1-d incubation at 37 degrees C. Since C. acetobutylicum alpha-amylase has a high activity and stability at low pH, this strain can potentially be employed in a one-step direct solvent-yielding fermentation of sago starch. However, the C. acetobutylicum glucoamylase was only stable at pH 4-5, maintaining more than 90% of its maximum activity after a 1-d incubation at 37 degrees C.
    Matched MeSH terms: Fermentation
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