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Background. Lactobacillus acidophilus not only improves the intestinal flora balance but also inhabits the growth of undesirable microorganisms in intestine, which is benefit to the health of humans and animals. Plackett-Burman and steepest ascent experiment are the rapid and concise ways of screening the main effective factors. This study is aimed to select the main influence factors and optimize the medium for Lactobacillus acidophilus by Plackett-Burman experiment and steepest ascent experiment. Material and methods. The ideal carbon source was screened among glucose, maltose, lactose and whey powder, and the ideal nitrogen source was screened among casein hydrolysate, peptone, yeast extract powder, fish meal, carbamide, ammonium sulfate and sodium nitrate by single factor experiment. Plackett-Burman and steepest ascent experiment were applied to screen the main effective factors of Lactobacillus acidophilus among peptone, beef extract, yeast extract powder, glucose, K2HP04, C6H1407N2, CH3COONa, MgS04 and Tween-80. Result. The results indicated that glucose (p = 0.01510) as negative factor and K,HP04 ip = 0.02017) as positive effect were the significant growth factors of Lactobacillus acidophilus, CH3COONa (p = 0.09273) as positive effect was an important factor, and the optimized medium was as follows: glucose - 21 g/L, K2HP04 - 3.5 g/L, CH3COONa - 6.5 g/L, peptone - 10 g/L, beef extract - 8 g/L, yeast extract powder - 8 g/L, C6H1407N2 - 2 g/L, MgS04 - 0.2 g/L and Tween-80 - 1 mL/L when the maximum viable count could achieve 2.72* 109 cfii/mL. Discussion. The experimental model is reliable and the experimental results are of good stability. Variance analysis is performed to determine the adequacy and significance of the linear model. Thus, Plackett-Burman and steepest ascent experiment improve the veracity of optimization the medium for Lactobacillus acidophilus compared with the previous research.
The Huaihe River Basin is located in-between the north-south climate transitional zone in China and is China’s important congested area and production base. The land-use of the environment was occupied by the land-use for social and economics. This paper aims to have a comprehensive understanding about land-use and vegetation evolution of the basin over the past 30 years. In view of 5 years (1985, 1990, 2000, 2005, and 2014) land-use data and remote sensing data about NDVI, land-use dynamic degree, and land-use transfer matrix were used to analyze the dynamics of land use. Spatial overlay was used to study vegetation change characteristics of the basin. The present study investigates the evolution trend of vegetation coverage based on spatial overlay analysis. We found that water bodies and urban lands of the basin increased during 1985-2014. On the other hand, the area of artificial vegetation, natural vegetation, and wetland were reduced. The impact was gradually increased by human intervention on various land use types. Overall vegetation coverage level shows deteriorative development, and distribution areas were discrete. The excellent vegetation coverage of natural vegetation and wetland didn’t have obvious changes, but the high coverage significantly decreased. Taken as a whole, the natural vegetation coverage was reduced. The vegetation coverage level of artificial water in the land-use for social and economics had greatly increased, but the overall trend of vegetation coverage level of artificial vegetation and resident construction land showed a decreasing trend.
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