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1.
Buatong Jirayu Phongpaichit Souwalak Rukachaisirikul Vatcharin Sakayaroj Jariya 《World journal of microbiology & biotechnology》2011,27(12):3005-3008
The aim of this work was to select endophytic fungi from mangrove plants that produced antimicrobial substances. Minimal inhibitory
concentrations (MIC) and minimal bactericidal concentrations (MBC) or minimal fungicidal concentrations (MFC) of crude extracts
from 150 isolates were determined against potential human pathogens by a colorimetric microdilution method. Ninety-two isolates
(61.3%) produced inhibitory compounds. Most of the extracts (28–32%) inhibited Staphylococcus aureus (MIC/MBC 4–200/64–200 μg ml−1). Only two extracts inhibited Pseudomonas aeruginosa (MIC/MBC 200/>200 μg ml−1). 25.5 and 11.7% inhibited Microsporum gypseum and Cryptococcus neoformans (MIC/MFC 4–200/8–200 μg ml−1 and 8–200/8–200 μg ml−1, respectively), while 7.5% were active against Candida albicans (MIC/MFC 32–200/32–200 μg ml−1). None of the extracts inhibited Escherichia coli. The most active fungal extracts were from six genera, Acremonium, Diaporthe, Hypoxylon, Pestalotiopsis, Phomopsis, and Xylaria as identified using morphological and molecular methods. Phomopsis sp. MA194 (GU592007, GU592018) isolated from Rhizophora apiculata showed the broadest antimicrobial spectrum with low MIC values of 8–32 μg ml−1against Gram-positive bacteria, yeasts and M. gypseum. It was concluded that endophytic fungi from mangrove plants are diverse, many produce compounds with antimicrobial activity
and could be suitable sources of new antimicrobial natural products. 相似文献
2.
Ping Su Anders Henriksson Christina Nilsson Hazel Mitchell 《World journal of microbiology & biotechnology》2008,24(9):1837-1842
The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three
probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against
Staphylococcus aureus and Streptococcus pyogenes (100 μg ml−1) were considerably lower than those against the probiotic strains tested (>800 μg ml−1) and Escherichia coli (800 μg ml−1). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both
Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by
24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately.
These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections
caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important
adjuncts to, or alternatives to, conventional antibiotic therapy. 相似文献
3.
Koo H Rosalen PL Cury JA Ambrosano GM Murata RM Yatsuda R Ikegaki M Alencar SM Park YK 《Current microbiology》2000,41(3):192-196
The effects of a new variety of propolis, from Northeastern Brazil (BA), on growth of mutans streptococci, cell adherence,
and water-insoluble glucan (WIG) synthesis were evaluated. Propolis from Southeastern (MG) and Southern (RS) Brazil were also
tested as an extension of our previous work. Ethanolic extracts of propolis (EEP) were prepared and analyzed by reversed-phase
HPLC. For the antibacterial activity assays, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations
(MBC) of EEPs against Streptococcus mutans, S. sobrinus, and S. cricetus were determined. Cell adherence of S. mutans and S. sobrinus to a glass surface was measured spectrophotometrically at 550 nm. WIG synthesized from sucrose by glucosyltransferase (Gtf)
was extracted and quantified by the phenol-sulfuric method. The HPLC profile of the new variety of propolis was entirely different
from Southeastern and Southern propolis. Neither flavonoid aglycones nor p-coumaric acid were detected in EEP BA. All EEPs demonstrated biological activities against mutans streptococci; EEP BA showed
the highest potency in all in vitro parameters evaluated in this study. The ranges of MIC values were 50 (EEP BA)–400 μg/ml
(MG), for S. mutans; and 25 (BA)–400 μg/ml (MG), for S. sobrinus and S. cricetus. The bactericidal concentration of EEPs was four to eight times the MIC values. The adherence of S. mutans and S. sobrinus cells and WIG synthesis were markedly inhibited by EEPs, demonstrating significant inhibition at all concentrations compared
with the control (80% ethanol) (p < 0.05). EEP BA showed 80% inhibition of cell adherence and WIG synthesis at concentrations as low as 12.5 and 7.8 μg/ml, respectively.
The results show that the new variety of propolis was exceptionally effective in all in vitro parameters tested against mutans
streptococci; biological effects of propolis are likely not to be due solely to flavonoids and (hydroxy)cinnamic acid derivatives.
Received: 14 February 2000 / Accepted: 8 May 2000 相似文献
4.
Teodora Janković Branka Vinterhalter Dijana Krstić-Milošević Radomirka Nikolić Dragan Vinterhalter Slobodan Milosavljević 《Acta Physiologiae Plantarum》2011,33(4):1515-1520
Shoot cultures of Gentianella bulgarica established from seedling epicotyls were maintained on MS medium supplemented with BA 0.2 mg l−1 + NAA 0.1 mg l−1. Cultures were prone to precocious flowering requiring the use of small shoot buds for multiplication purposes. The contents
of three xanthone compounds identified as DGL, BGL, and DMB, in different plant material were determined by HPLC. The analysis
revealed that the production of xanthones was affected by different concentrations of BA in medium. Shoot cultures grown at
higher BA concentrations contained more DGL than material grown in nature. The concentrations of other two xanthones were
lower in shoot cultures than in plants from nature. The radical scavenging activity of plant extracts and xanthones was investigated
by DPPH test. Samples from plants grown in nature showed the highest activity (IC50 = 0.26 mg ml−1), while the extracts of shoot cultures grown in media with higher concentrations of BA showed moderate activities (IC50 from 1.6 to 4.4 mg ml−1). 相似文献
5.
An endophytic Xylaria sp., having broad antimicrobial activity, was isolated and characterized from Ginkgo biloba L. From the culture extracts of this fungus, a bioactive compound P3 was isolated by bioactivity-guided fractionation and
identified as 7-amino-4-methylcoumarin by nuclear magnetic resonance, infrared, and mass spectrometry spectral data. The compound
showed strong antibacterial and antifungal activities in vitro against Staphylococcus aureus [minimal inhibitory concentrations (MIC) 16 μg·ml−1], Escherichia coli (MIC, 10 μg·ml−1), Salmonella typhia (MIC, 20 μg·ml−1), Salmonella typhimurium (MIC, 15 μg·ml−1), Salmonella enteritidis (MIC, 8.5 μg·ml−1), Aeromonas hydrophila (MIC, 4 μg·ml−1), Yersinia sp. (MIC, 12.5 μg·ml−1), Vibrio anguillarum (MIC, 25 μg·ml−1), Shigella sp. (MIC, 6.3 μg·ml−1), Vibrio parahaemolyticus (MIC, 12.5 μg·ml−1), Candida albicans (MIC, 15 μg·ml−1), Penicillium expansum (MIC, 40 μg·ml−1), and Aspergillus niger (MIC, 25 μg·ml−1). This is the first report of 7-amino-4-methylcoumarin in fungus and of the antimicrobial activity of this metabolite. The
obtained results provide promising baseline information for the potential use of this unusual endophytic fungus and its components
in the control of food spoilage and food-borne diseases. 相似文献
6.
Luna JM Rufino RD Sarubbo LA Rodrigues LR Teixeira JA de Campos-Takaki GM 《Current microbiology》2011,62(5):1527-1534
Different groups of biosurfactants exhibit diverse properties and display a variety of physiological functions in producer
microorganisms; these include enhancing the solubility of hydrophobic/water-insoluble compound, heave metal binding, bacterial
pathogenesis, cell adhesion and aggregation, quorum sensing and biofilm formation. Candida sphaerica was grown in a low cost medium, consisting of distilled water supplemented with 9% refinery residue of soybean oil and 9%
corn steep liquor, for 144 h at 28°C and 150 rpm. The cell-free supernatant obtained at the end of the experiments was submitted
to extraction, and afterward the biosurfactant was isolated using methanol with a yield of 9 g l−1. The critical micelle concentration of the biosurfactant was found to be 0.25 mg ml−1 with a surface tension of 25 mN m−1. Several concentrations of the biosurfactant (0.625–10 mg ml−1) were used to evaluate its antimicrobial and antiadhesive activities against a variety of microorganisms. The biosurfactant
showed antimicrobial activity against Streptococcus oralis (68%), Candida albicans (57%), and Staphylococcus epidermidis(57.6%) for the highest concentration tested. Furthermore, the biosurfactant at a concentration of 10 mg ml−1 inhibited the adhesion between 80 and 92% of Pseudomonas aeruginosa, Streptococcus agalactiae, Streptococcus sanguis12. Inhibition of adhesion with percentages near 100% occurred for the higher concentrations of biosurfactant used. Results gathered
in this study point to a potential use of the biosurfactant in biomedical applications. 相似文献
7.
Microbacterium esteraromaticum was isolated from ginseng field. The β-glucosidase gene (bgp1) from M. esteraromaticum was cloned and expressed in Escherichia coli BL21 (DE3). The bgp1 gene consists of 2,496 bp encoding 831 amino acids which have homology to the glycosyl hydrolase family 3 protein domain.
The recombinant β-glucosidase enzyme (Bgp1) was purified and characterized. The molecular mass of purified Bgp1 was 87.5 kDa,
as determined by SDS-PAGE. Using 0.1 mg ml−1 enzyme in 20 mM sodium phosphate buffer at 37°C and pH 7.0, 1.0 mg ml−1 ginsenoside Rb1 was transformed into 0.444 mg ml−1 ginsenoside Rg3 within 6 h. The Bgp1 sequentially hydrolyzed the outer and inner glucose attached to the C-20 position of
ginsenosides Rb1. Bgp1 hydrolyzed the ginsenoside Rb1 along the following pathway: Rb1 → Rd → 20(S)-Rg3. This is the first report of the biotransformation of ginsenoside Rb1 to ginsenoside 20(S)-Rg3 using the recombinant β-glucosidase. 相似文献
8.
Bo Long Alex X. Niemiera Zhi-ying Cheng Chun-lin Long 《Plant Cell, Tissue and Organ Culture》2010,101(2):151-162
The effects of seed maturity, media type, carbon source, and organic nutrient additives on seed germination, protocorm development,
and plant growth of Paphiopedilum villosum var. densissimum Z. J. Liu et S. C. Chen were investigated. Micropropagation frequency was enhanced through the use of 200-day-old seed, Knudson
C (KC) medium, and the presence of both glucose and coconut milk in the medium. The effects of various plant growth regulators
on the frequency of shoot organogenesis in four Paphiopedilum species were also investigated. Explants of P. villosum var. densissimum and P. insigne (Lindl.) Stein incubated in the presence of 5 mg l−1 6-benzyladenine (BA) with 0.5 mg l−1 α-naphthalene acetic acid (NAA) and 0.2 mg l−1 BA with 0.1 mg l−1 NAA, respectively, showed a twofold increase in the frequency of shoot organogenesis. For explants of P. bellatulum (Rchb. f.) Stein and P. armeniacum S. C. Chen et F. Y. Liu, the combination of 5.5 mg l−1 BA with 0.5 mg l−1 NAA and 4 mg l−1 BA with 0.1 mg l−1 NAA, respectively, resulted in the highest frequencies of shoot organogenesis. 相似文献
9.
Wiyakrutta Suthep Sriubolmas Nongluksna Panphut Wattana Thongon Nuntawan Danwisetkanjana Kannawat Ruangrungsi Nijsiri Meevootisom Vithaya 《World journal of microbiology & biotechnology》2004,20(3):265-272
A total of 81 Thai medicinal plant species collected from forests in four geographical regions of Thailand were examined for
the presence of endophytic fungi with biological activity. Of 582 pure isolates obtained, 360 morphologically distinct fungi
were selected for cultivation on malt Czapek broth and yeast extract sucrose broth, from which extracts were tested for biological
activity. Extracts of 92 isolates could inhibit Mycobacterium tuberculosis (MIC 0.0625–200 μg ml−1) when tested by the microplate Alamar blue assay, while extracts of six inhibited Plasmodium falciparum (IC50 of 1.2–9.1 μg ml−1) as determined by the [3H]hypoxanthine incorporation method. Strong anti-viral activity against Herpes simplex virus type 1 was observed in 40 isolates
(IC50 of 0.28–50 μg ml−1). The sulphorhodamine B assay for activity against cancer cell lines revealed that 60 were active against human oral epidermoid
carcinoma cells (EC50 0.42–20 μg ml−1) and 48 against breast cancer cells (EC50 0.18–20 μg ml−1). Bioactivity profile was affected by the type of culture medium. Given the high incidence of bioactive extracts and the
fact that most of the isolated fungi could not be identified due to lack of spore formation, the results suggested that Thai
medicinal plants can provide a wide variety of endophytes that might be a potential source of novel bioactive compounds.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Juan Wang Wen-Yuan Gao Jian Zhang Tao Huang Tian-Tian Wen Lu-Qi Huang 《Acta Physiologiae Plantarum》2011,33(3):861-866
Lactoalbumin hydrolysate (LH) at 100 mg L−1 with methyl jasmonate (MJ) at 2 mg L−1 synergistically stimulated ginsenoside accumulation in Panax quinquefolium cells compared with 100 mg L−1 LH. Combination elicitors led to higher ginsenoside productivity (45.93 mg L−1) than single treatment of 100 mg L−1 LH (31.37 mg L−1). This present result will be helpful in providing a tool for enhancing the productivity of ginsenoside by Panax quinquefolium cell cultures on a commercial scale. 相似文献
11.
Chávez-Quintal P González-Flores T Rodríguez-Buenfil I Gallegos-Tintoré S 《Indian journal of microbiology》2011,51(1):54-60
Bioactive compounds from vegetal sources are a potential source of natural antifungic. An ethanol extraction was used to obtain
bioactive compounds from Carica papaya L. cv. Maradol leaves and seeds of discarded ripe and unripe fruit. Both, extraction time and the papaya tissue flour:organic
solvent ratio significantly affected yield, with the longest time and highest flour:solvent ratio producing the highest yield.
The effect of time on extraction efficiency was confirmed by qualitative identification of the compounds present in the lowest
and highest yield extracts. Analysis of the leaf extract with phytochemical tests showed the presence of alkaloids, flavonoids
and terpenes. Antifungal effectiveness was determined by challenging the extracts (LE, SRE, SUE) from the best extraction
treatment against three phytopathogenic fungi: Rhizopus stolonifer, Fusarium spp. and Colletotrichum gloeosporioides. The leaf extract exhibited the broadest action spectrum. The MIC50 for the leaf extract was 0.625 mg ml−1 for Fusarium spp. and >10 mg ml−1 for C. gloeosporioides, both equal to approximately 20% mycelial growth inhibition. Ethanolic extracts from Carica papaya L. cv. Maradol leaves are a potential source of secondary metabolites with antifungal properties. 相似文献
12.
Diversity of lactic acid bacteria and yeasts in Airag and Tarag,traditional fermented milk products of Mongolia 总被引:2,自引:1,他引:1
Koichi Watanabe Junji Fujimoto Masae Sasamoto Jamyan Dugersuren Tseveendori Tumursuh Shirchin Demberel 《World journal of microbiology & biotechnology》2008,24(8):1313-1325
We used culture- and molecular-biology-based methods to investigate microbial diversity in the traditional Mongolian fermented
milks “Airag” (fermented mare’s milk) and “Tarag” (fermented milk of cows, yaks, goats, or camels). By rRNA or functional
gene sequencing, we identified 367 lactic acid bacteria (LAB) strains and 152 yeast strains isolated from 22 Airag and 31
Tarag samples. The total concentration of LAB in Airag (107.78 ± 0.50 c.f.u. ml–1; mean ± SD) was significantly lower (P < 0.01) than in Tarag (108.35 ± 0.62 c.f.u. ml−1), whereas the total concentration of yeasts in Airag (107.41 ± 0.61 c.f.u. ml-1) was significantly higher (P < 0.01) than in Tarag (105.86 ± 1.29 c.f.u. ml-1). Lactobacillus helveticus and Lactobacillus kefiranofaciens were isolated from Airag as the predominant LAB strains at levels of about 107 c.f.u. ml−1, whereas Lactobacillus delbrueckii subsp. bulgaricus, L. helveticus, and Streptococcus thermophilus were the predominant isolates from Tarag at about 107 c.f.u. ml−1. The lactose-fermenting Kluyveromyces marxianus was isolated predominantly from Airag as its major alcoholic fermentation component. Non-lactose-fermenting yeasts such as
Saccharomyces cerevisiae, Issatchenkia orientalis, and Kazachstania unispora were the predominant isolates from Tarag, at about 105 c.f.u. ml−1. The apparent geographic differences in the L. kefiranofaciens and S. thermophilus contents of Tarag strongly suggested that differences among the animal species from which the milk was sourced, rather than
geographic distances, were the most important factors influencing the diversity of the microbial composition of traditional
fermented milks in Mongolia. 相似文献
13.
Behzad Ahmadi Khoshnood Alizadeh Jaime A. Teixeira da Silva 《Plant Cell, Tissue and Organ Culture》2012,109(3):525-533
The effects of three periods of incubation (10, 20 and 30 min) at different levels of bleomycin (0, 0.1, 0.2, 0.3, 0.4 and
0.5 μg ml−1), as well as three periods of exposure (12, 24 and 48 h) to different levels of the anti-auxin p-chlorophenoxyisobutyric acid (PCIB), including 1, 2, 3, 4 and 5 mg l−1, on microspore embryogenesis of rapeseed cv. ‘Amica’ were investigated. Microspore embryogenesis was significantly enhanced
following 20 min treatment with 0.2 μg ml−1 bleomycin compared with untreated cultures. Highest embryo yield (163 embryos Petri dish−1) was observed with 24 h treatment of 4 mg l−1 PCIB. The highest percentage of secondary embryogenesis was observed on B5 medium containing 0.15 mg l−1 of gibberellic acid (GA3) and 0.2 mg l−1 6-benzyladenine (BA) in 4–6 mm microspore-derived embryos (MDEs). Most callus formed on B5 medium containing 0.15 mg l−1 GA3, 0.1 mg l−1 BA and 0.1 mg l−1 indole-3-acetic acid (IAA) when 4–6 mm embryos were used. Regeneration was highest on B5 medium containing 0.05 mg l−1 GA3 or 0.1 mg l−1 BA and 0.2 mg l−1 IAA with 2–4 mm embryos. Microspore embryogenesis and plant regeneration could be improved by both bleomycin and PCIB when
the appropriate MDE length and phytohormone level were selected. 相似文献
14.
Meiru Li Hongqing Li Xiaoying Hu Xiaoping Pan Guojiang Wu 《Plant Cell, Tissue and Organ Culture》2011,106(3):363-371
Saussurea involucrata is a valuable traditional Chinese medicinal herb. This is the first report of a successful genetic transformation protocol
for S. involucrata using Agrobacterium tumefaciens. Leaf explants were incubated with A. tumefaciens strain EHA105 harboring the binary vector pCAMBIA 1301, which contains the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following
co-cultivation, about 23.7% of the explants produced hygromycin-resistant calli on MS basal medium (Murashige and Skoog in
Physiol Plant 15: 473–497, 1962) supplemented with 1 mg l−1 benzyladenine (BA), 0.1 mg l−1 α-naphthaleneacetic acid (NAA), 0.1 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D), 20 mg l−1 hygromycin, and 500 mg l−1 cefotaxime. Shoots were regenerated following transfer of the resistant calli to shoot induction medium containing 1.5 mg l−1 BA, 0.1 mg l−1 NAA, 0.25 mg l−1 gibberellic acid (GA3), 20 mg l−1 hygromycin, and 250 mg l−1 cefotaxime, and about 67.5% of the resistant calli differentiated into shoots. Finally, 80% of the hygromycin-resistant shoots
rooted on MS media supplemented with 0.2 mg l−1 NAA, 20 mg l−1 hygromycin, and 250 mg l−1 cefotaxime. The transgenic nature of the transformants was demonstrated by detection of β-glucuronidase activity in the primary
transformants and by Southern blot hybridization analysis. About 16% of the total inoculated leaf explants produced transgenic
plants after approximately 5 months. Using this optimized transformation system, a rice ortholog of the Arabidopsis FLOWERING LOCUS T gene, Hd3a, was transferred into S. involucrata. Introduction of this gene caused an early-flowering phenotype in S. involucrata. 相似文献
15.
Teresa Manso Carla Nunes Sara Raposo Maria Emília Lima-Costa 《Journal of industrial microbiology & biotechnology》2010,37(11):1145-1155
Large-scale production has been the major obstacle to the success of many biopesticides. The spreading of microbial biocontrol
agents against postharvest disease, as a safe and environmentally friendly alternative to synthetic fungicides, is quite dependent
on their industrial mass production from low-cost raw materials. Considerable interest has been shown in using agricultural
waste products and by-products from food industry as nitrogen and carbon sources. In this work, carob pulp aqueous extracts
were used as carbon source in the production of the biocontrol agent Pantoea agglomerans PBC-1. Optimal sugar extraction was achieved at a solid/liquid ratio of 1:10 (w/v), at 25°C, for 1 h. Batch experiments were
performed in shake flasks, at different concentrations and in stirred reactors at two initial inoculums concentrations, 106 and 107 cfu ml−1. The initial sugar concentration of 5 g l−1 allowed rapid growth (0.16 h−1) and high biomass productivity (0.28 g l−1 h−1) and was chosen as the value for use in stirred reactor experiments. After 22 and 32 h of fermentation the viable population
reached was 3.2 × 109 and 6.2 × 109 cfu ml−1 in the fermenter inoculated at 106 cfu ml−1 and 2.7 × 109 and 6.7 × 109 cfu ml−1 in the bioreactor inoculated at 107 cfu ml−1. A 78% reduction of the pathogen incidence was achieved with PBC-1 at 1 × 108 cfu ml−1, grown in medium with carob extracts, on artificially wounded apples stored after 7 days at 25°C against P. expansum. 相似文献
16.
A plant growth-promoting rhizobacterium (PGPR) was isolated and identified as Gordonia sp. S2RP-17, which showed ACC deaminase and siderophore synthesizing activities. Its maximum specific growth rate was 0.54 ± 0.12 d−1 at 5,000 mg L−1 of total petroleum hydrocarbon (TPH), and its maximum diesel degradation rate was 2,434.0 ± 124.4 mg L−1 d−1 at 20,000 mg L−1 of TPH. The growth of Zea mays was significantly promoted by the inoculation of Gordonia sp. S2RP-17 in the diesel-contaminated soil. Measured TPH removal efficiencies by various means were 13% by natural attenuation,
84.5% by planting Zea mays, and 95.8% by the combination of Zea mays and Gordonia sp. S2RP-17. The S2RP-17 cell counts were maintained at 1 × 106 CFU g-soil−1 during the remediation period, although they slightly decreased from their initial numbers (2.94 × 107 CFU g-soil−1). These results indicate that rhizoremediation using both Zea mays and Gordonia sp. S2RP-17 is a promising strategy for enhancing remediation efficiency of diesel-contaminated soils. 相似文献
17.
Pratibha Dheeran Sachin Kumar Yogesh K. Jaiswal Dilip K. Adhikari 《Applied microbiology and biotechnology》2010,86(6):1857-1866
A newly isolated Geobacillus sp. IIPTN (MTCC 5319) from the hot spring of Uttarakhand's Himalayan region produced a hyperthermostable α-amylase. The microorganism
was characterized by biochemical tests and 16S rRNA gene sequencing. The optimal temperature and pH were 60°C and 6.5, respectively,
for growth and enzyme production. Although it was able to grow in temperature ranges from 50 to 80°C and pH 5.5–8.5. Maximum
enzyme production was in exponential phase with activity 135 U ml−1 at 60°C. Assayed with cassava as substrate, the enzyme displayed optimal activity 192 U ml−1 at pH 5.0 and 80°C. The enzyme was purified to homogeneity with purification fold 82 and specific activity 1,200 U mg−1 protein. The molecular mass of the purified enzyme was 97 KDa. The values of K
m
and V
max were 36 mg ml−1 and 222 μmol mg−1 protein min−1, respectively. The amylase was stable over a broad range of temperature from 40°C to 120°C and pH ranges from 5 to 10. The
enzyme was stimulated with Mn2+, whereas it was inhibited by Hg2+, Cu2+, Zn2+, Mg2+, and EDTA, suggesting that it is a metalloenzyme. Besides hyperthermostability, the novelty of this enzyme is resistance
against protease. 相似文献
18.
l-DOPA is an amino acid derivative and most potent drug used against Parkinson’s disease, generally obtained from Mucuna pruriens seeds. In present communication, we have studied the in vitro production of l-DOPA from l-tyrosine by novel bacterium Bacillus sp. JPJ. This bacterium produced 99.4% of l-DOPA from l-tyrosine in buffer (pH 8) containing 1 mg ml−1 cell mass incubated at 40°C for 60 min. The combination of CuSO4 and l-ascorbic acid showed the inducing effect at concentrations of 0.06 and 0.04 mg ml−1, respectively. The activated charcoal 2 mg ml−1 was essential for maximum bioconversion of l-tyrosine to l-DOPA and the crude tyrosinase activity was 2.7 U mg−1 of tyrosinase. Kinetic studies showed significant values of Y
p/s (0.994), Q
s (0.500) and q
s (0.994) after optimization of the process. The production of l-DOPA was confirmed by analytical techniques such as HPTLC, HPLC and GC–MS. This is the first report on rapid and efficient
production of l-DOPA from l-tyrosine by bacterial source which is more effective than the plant, fungal and yeast systems. 相似文献
19.
Production rates, abundance, chlorophyll a (Chl a) concentrations and pigment composition were measured for three size classes (<2 μm, 2–11 μm and >11 μm) of phytoplankton
from May to December 2000 in deep, mesotrophic, alpine lake Mondsee in Austria. The study focuses on differences among phytoplankton
size fractions characterised by their surface area to volume ratio ([mm2 l−1: mm3l−1]), pigment distribution patterns and photosynthetic rates. Particular attention was paid to autotrophic picophytoplankton
(APP, fraction <2 μm) since this size fraction differed significantly from the two larger size fractions. Among the three
fractions, APP showed the highest surface area to volume ratios and a high persistence in the pattern of lipophilic pigments
between temporarily and spatially successive samples (about 80% similarity of pigment composition between samples over seasons
and depths). The epilimnetic abundance of APP varied seasonally with an annual maximum of 180 × 103 cells ml−1 in June (at 4–9 m). The minimum (October at 12 m) was more than an order of magnitude lower (4.9 × 103 ml−1). APP peaked during autumn and contributed between 24% and 42% to the total area-integrated Chl a (10–23 mg m−2) and between 16% and 58% to total area-integrated production (5–64 mg m−2 h−1) throughout seasons. 相似文献
20.
H. Yu X. Ren F. Yang Y. Xie Y. Guo Y. Cheng W. Yao 《Letters in applied microbiology》2022,74(2):258-267
Cinnamomum camphora chvar. Borneol essential oil (BEO) was efficiently extracted by using pilot-plant neutral cellulase-assisted steam distillation (NCSD). Borneol, β-cadinene and α-caryophyllene were identified as major components. Bacillus subtilis was the most sensitive bacteria to BEO with the lowest minimal inhibition concentration (MIC) and minimal bactericial concentration (MBC) at 1·75 and 3·50 mg ml−1, respectively. Antimicrobial activity of the BEO was also reasonably high against Salmonella typhimurium, Escherichia coli and Staphylococcus aureus, but not sensitive against two fungi, i.e. Aspergillus niger and Penicillium aurantiogriseum. Changes in permeability and integrity of cell membrane, damage of cell wall and further leakage out of metabolites and ions were determined as bactericidal mechanisms of BEO against the two gram-positive bacteria. The BEO showed a reasonably high repelling activity of dust mite, which achieved higher than 95% repelling dust mite activity after the treatment of BEO solution at 0·50 mg ml−1. When the concentration of BEO was higher than 0·50 mg ml−1, it was B-grade miticide with miticidal activity higher than 95%. Miticidal procedures were characterized as excitation, contraction, relaxation and lastly leading to the death of dust mite. It is speculated that the BEO would cause dehydration and death of dust mite as neuromuscular toxicity. 相似文献