棕榈藤的热软化:半纤维木素基质的影响

利用蠕变柔量实验检测8种棕榈藤植物细胞壁的半纤维素木素基质，了解其对棕榈藤热软化影响。首先用乙醇-苯准备提取的单体样本，随后是用在木材上使用的标准程序对藤细胞进行化学分析。结果显示为细胞壁是42％～53％α-纤维素，19％～27％半纤维素和20％～40％木素。蠕变柔量实验表明，样品软化程度取决于热量的提供情况。提取的单体软化是在70～85℃时开始的，全纤维素在75～95℃时软化，而α-纤维素样品在100℃时软化。8种品种的热软化程度差异也被观测到。它们的差异取决于品种间半纤维素木素的比例的不同：基质的容量越大，分子运动越剧烈。同时还注意到从提取的单体的原料到全纤维素再到α-纤维素样品在热软化中的还原性差异。它取决于基质的还原量，因为木素去除了。α-纤维素还有其它的运动。这些运动仅衍生于纤维素链中的晶体-非晶体区域。物质的晶体越多，可观测的分子运动越小。     

利用聚类分析方法分析人工和野生省藤属的形态特征

本文利用聚类分析方法分析了棕榈藤形态特征,这些特性影响到棕榈藤的生长特征和整体性质。聚类分析和主要组分分析显示出人工和野生这2种类型省藤属有相似之处。这表明,在加工过程中人工藤和野生藤在各方面相差无几。结果是,最终藤产品的质量都几乎相同。为此,藤工业不再单纯利用野生藤,因为人工藤是一种很好的替代品。     

影响省藤弹性的参数和弹性方程式的确定

本文评估了省藤结构(基本薄壁组织和微管束分布)、物理特征(微纤维角度、结晶度和非晶区)和细胞壁化学成分(纤维素、半纤维素和木质素)对压缩应力的影响,以确定一个能测定省藤弹性的数学模式。进行了图象分析,碘染色,x光衍射技术和标准化学分析。最后,用热机械分析仪测定了压缩应力。回归方程表明,在不同参数中,基本薄壁组织比例、微纤维角度、非晶区大小和半纤维含量与压缩应力呈正相关。多元回归的数学方程为Y=0.012x₂-0.0001x₁+0.016x₃+0.017x₄-1.861,其中Y=压缩应力,x₂=微纤维角度,x₁=基本薄壁组织,x₃=非晶区,x₄=半纤维含量。在这些参数中,当P=0.050,半纤维含量的影响最大。     

人工种植省藤的性能特征

对人工种植的棕榈藤和野生藤的力学特性进行对比。同时,评估了比重和纤维比对强度的变异性的影响,并评估了强度特性对藤龄的影响。人工种植和野生藤的断裂模数和弹性模数相似,由此证明人工种植藤的强度特性并不亚于野生藤的强度特性。这说明,人工藤可在工业上利用,且对藤产品的性能没有负面影响。绝干比重和纤维比也没有对其强度特性的变异性产生影响。同样,藤龄也不会对强度特性产生影响。很明显,幼龄藤也具有成熟藤秆相同的强度。     

Enhancing growth and resistance to Vibrio alginolyticus disease in catarina scallop (Argopecten ventricosus) with Bacillus and Lactobacillus probiotic strains during early development

In bivalve aquaculture, selecting suitable probiotic treatments can be crucial for improving hatchery‐rearing of larvae and juveniles. We assessed the potential of five bacterial strains, previously selected in vitro, to improve survival, growth and resistance of catarina scallop Argopecten ventricosus during early and late larval and juvenile developmental stages, as well as during exposure to the pathogen Vibrio alginolyticus. Hatchery‐reared larvae and juveniles were treated with eight treatments of single or combined strains of Bacillus and Lactobacillus at 1 × 10⁶ CFU mL^?1 every 48 h for 9 days (larvae) and 21 days (juveniles). Compared with the control, significantly higher survival and growth in size and weight of early veliger larvae occurred with the antibiotic and the RL5 (Lactobacillus graminis) treatments. Significantly enhanced settlement of pediveliger larvae occurred with a different probiotic strain, the mix of Lactobacillus and Bacillus (MIX‐LB), while higher survival and growth of early juveniles occurred with C3 (Lactobacillus plantarum). The mix of Bacillus (MIX‐B) significantly increased survival of juveniles from V. alginolyticus after 120‐h infection, consistent with maximum activity of superoxide dismutase enzyme. In contrast, all untreated and infected scallops died by 96 h. The three Bacillus strains performed poorly when used as single treatments and when given to early developing larvae. Our results indicate that the action mechanism of probiotic strains is stage specific and strain specific, generating different responses by the host, including improved survival and growth (likely from better nutrient assimilation) and higher resistance against pathogens (possibly from strengthening the immune system).     

Isolation and use of beneficial microbiota from the digestive tract of lions‐paw scallop Nodipecten subnodosus and winged pearl oyster Pteria sterna in oyster aquaculture

We isolated microbiota from the digestive tract of Nodipecten subnodosus and Pteria sterna and determined in vitro their haemolytic activity, antagonism against Vibrio spp., bacterial hydrophobicity, production of extracellular enzymes and molecular identification. Five bacterial strains were selected: RL5 and C3 (Lactobacillus spp.) and PB1‐1, PB1‐5 and PB1‐6 (Bacillus spp.). The RL5 and C3 isolates showed antimicrobial activity against Vibrio spp. and the PB1‐1, PB1‐5 and PB1‐6 isolates showed enzymatic activity for amylase, protease, lipase and cellulose; the C3 and PB1‐5 isolates were highly hydrophobic. The selected strains of bacteria were tested in vivo as probiotics, together with a treatment of ampicillin and a control without bacteria on juvenile Kumamoto oysters Crassostrea sikamea. The strains were provided individually and as mixes of isolates. Survival, growth and biochemical composition of the juveniles were determined as in vivo indicators. Juveniles grew significantly larger and faster when treated with a specific mix of isolates (MIX‐B), compared with the control. The protein, lipid and carbohydrate concentrations were also significantly higher in oysters exposed to probiotic treatments, compared with the control and the antibiotic treatment. The selected microbiota showed probiotic proprieties for cultivating C. sikamea juveniles.