Decaying wood samples were collected, and actinomycetes were isolated and screened for laccase production. The identity of the efficient laccase-producing isolate was confirmed by using a molecular approach. Fermentation conditions for laccase production were optimized, and laccase biochemical properties were studied.
Results
Based on the 16S rRNA gene sequencing and phylogenetic analysis, the isolate coded as HWP3 was identified as Streptomyces sp. LAO. The time-course study showed that the isolate optimally produced laccase at 84 h with 40.58?±?2.35 U/mL activity. The optimized physicochemical conditions consisted of pH 5.0, ferulic acid (0.04%; v/v), pine back (0.2 g/L), urea (1.0 g/L), and lactose (1 g/L). Streptomyces sp. LAO laccase was optimally active at pH and temperature of 8.0 and 90 °C, respectively, with remarkable pH and thermal stability. Furthermore, the enzyme had a sufficient tolerance for organic solvents after 16 h of preincubation, with laccase activity?>?70%. Additionally, the laccase maintained considerable residual activity after pretreatment with 100 mM of chemical agents, including sodium dodecyl sulphate (69.93?±?0.89%), ethylenediaminetetraacetic acid (93.1?±?7.85%), NaN3 (96.28?±?3.34%) and urea (106.03?±?10.72%).
Conclusion
The laccase's pH and thermal stability; and robust catalytic efficiency in the presence of organic solvents suggest its industrial and biotechnological application potentials for the sustainable development of green chemistry.
We assessed the seasonal abundance and distribution of Vibrio species as well as some selected environmental parameters in the treated effluents of two wastewater treatment plants (WWTP),
one each located in a suburban and urban community of Eastern Cape Province, South Africa. Vibrio population density ranged from 2.1×105 to 4.36×104 CFU/ml in the suburban community and from 2.80×105 to 1.80×105 CFU/ml in the urban community. Vibrio species associated with 180 μ, 60 μ, and 20 μ plankton sizes were observed at densities of 0–136×103 CFU/ml, 0–8.40×102 CFU/ml, and 0–6.80×102 CFU/ml, respectively at the suburban community’s WWTP. In the urban community, observed densities of culturable Vibrio were 0–2.80×102 CFU/ml (180 μ), 0–6.60×102 CFU/ml (60 μm), and 0–1.80× 103 CFU/ml (20 μm). The abundance of free-living Vibrio species ranged from 0 to 1.0×102 and 1.0×103 CFU/ml in the suburban and urban communities’ WWTPs, respectively. Molecular confirmation of the presumptive Vibrio isolates revealed the presence of V. fluvialis (41.38%), V. vulnificus (34.48%), and V. parahaemolyticus (24.14%) in the suburban community effluents. In the urban community molecular confirmation revealed that the same species
were present at slightly different percentages, V. fluvialis (40%), V. vulnificus (36%), and V. parahaemolyticus (24%). There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, but Vibrio species abundance was positively correlated with temperature (r=0.565; p<0.01), salinity, and dissolved oxygen (p<0.05). Turbidity and pH showed significant seasonal variation (p<0.05) across the seasons in both locations. This study underscores the potential of WWTPs to be sources of Vibrio pathogens in the watershed of suburban and urban communities in South Africa. 相似文献
目的:探讨钙离子拮抗剂拉西地平对高温高湿应激大鼠血管平滑肌细胞内内质网应激相关因子葡萄糖调节蛋白78(glucose-regulated protein of 78kD,GRP78)和C/EBP环磷酸腺苷反应元件结合转录因子同源蛋白(CAAT/enhancer binding protein homologous protein,CHOP)表达的影响。方法:将60只雄性SD大鼠随机分为对照组、高温高湿组、拉西地平组,每组20只。按实验时间(2w、4w、6w、8w)的不同,各组又分为4个亚组,每个亚组5只大鼠。用颈动脉插管法测定各组大鼠的平均动脉压(MAP);用免疫组织化学法检测GRP78和CHOP的表达水平。结果:①高温高湿各组的MAP随着实验时间的延长呈逐渐递增的趋势,高温高湿4w、6w、8w亚组的MAP均显著高于相应的对照组和拉西地平组(P〈0.05)。②随着实验时间的延长,高温高湿组GRP78表达量不断增加,6w达到最大值,8w表达减弱。高温高湿4w、6w、8w亚组GRP78表达量均高于相应对照组和拉西地平组,有显著性差异(P〈0.05)。③高温高湿组2w、4w、6w、8w亚组CHOP表达量组间比较有显著性差异(P〈0.05),8w亚组表达达到最高值;高温高湿组6w、8w亚组与相应对照组和拉西地平组比较有显著性差异(P〈0.05)。结论:高温高湿应激可引起血管平滑肌细胞内质网应激反应,导致GRP78表达及CHOP表达的不对称增加,提示高温高湿应激可引起血管平滑肌细胞的损害;拉西地平可以减轻内质网应激,逆转高温高湿应激所致的血管平滑肌细胞的损伤作用,对血管平滑肌细胞有保护作用。 相似文献