不同林龄杉木林下套种阔叶树对土壤磷组分的影响

套种是杉木人工林经营的重要措施,磷是南方森林生态系统中主要限制性养分元素之一,但套种模式对土壤磷素的影响尚不明确。以亚热带杉木人工林表层(0-10 cm)土壤为对象,研究套种林(杉阔套种幼林、杉阔套种成熟林)和杉木幼林土壤理化性质和土壤各形态磷含量差异,分析套种对杉木人工林土壤磷含量的影响。结果表明:(1)不同套种林显著改变土壤总磷、土壤总无机磷、土壤总有机磷、土壤微生物生物量磷(MBP)和土壤酸性磷酸酶活性(APA),大小顺序均为杉阔套种成熟林>杉阔套种幼林>杉木幼林。(2)土壤各磷组分中活性磷含量较低,其中NaHCO3-Po在活性组分中占主导;土壤NaOH-Po是中等活性磷的主要组分,杉阔套种成熟林尤为显著;闭蓄态磷(Residual-P)在总磷含量中最高。(3)与杉木幼林相比,杉阔套种成熟林显著增加了树脂提取态磷(Resin-Pi)、碳酸氢钠提取态有机和无机磷(NaHCO3-Pi、NaHCO3-Po)、氢氧化钠提取态有机和无机磷(NaOH-Pi、NaOH-Po)、氢氧化钠残留提取态有机磷(NaOHu.s-Po)、盐酸提取态磷(HCl-Pi)和闭蓄态磷(Residual-P)含量;土壤总无机磷、NaHCO3-Po、HCl-Pi、NaHCO3-Pi、NaOHu.s-Pi和Residual-P对杉阔套种幼林的响应不敏感。(4)除含水率外不同林龄下杉阔套种林土壤磷形态与土壤理化性质(土壤总碳氮、土壤可溶性有机氮、土壤微生物生物量磷、酸性磷酸酶)呈正相关性(P<0.05)。冗余分析表明,土壤磷组分的变化主要受MBP调控,且MBP与有机磷组分(NaOHu.s-Po、NaOH-Po)和HCI-Pi呈显著正相关。总之,套种林的土壤磷素有效性高于杉木幼林,土壤养分状况更佳。     

Fusarium solani Upregulated Sesquiterpene Synthase Expression,Sesquiterpene Production and Allelopathic Activity in Piper betle L.

Activators of sesquiterpene synthase (STS) gene expression and sesquiterpene production in Piper betle L. were examined using quantitative real time PCR and gas chromatography mass spectrometry methods, and the allelopathic activity of untreated and Fusarium solani-treated betel extracts was tested on seed germination and on the shoot and root growth of Thai rice variety PSL2 (Oryza sativa cv. Phitsanulok 2) and three dominant paddy weeds (Eclipta prostrata, Echinochloa crus-galli and Chloris barbata). The results demonstrated that F. solani dramatically upregulated STS expression and productions of β-cubebene, β-caryophyllene and germacrene D sesquiterpene when compared with the untreated control, and that betel extracts had a greater inhibitory effect on weeds than on rice. The effects were more clearly detected on seed germination and root growth than on shoot growth, and they were found to be dose-dependent. It is also noted that F. solani-treated extract had stronger effects than the untreated extract. The species most sensitive to the allelopathic effects was C. barbata, germination of which was completely inhibited even at a dose of 0.1 mg/mL untreated extract. With regards to rice, although betel extract at 1.0 mg/mL showed no inhibition on germination, it affected the elongation of rice roots, in addition to those of the tested weeds. The obtained data suggested that F. solani has potential as an activator of sesquiterpene allelochemical production via STS expression, the latter leading to the treated betel extract having a stronger phytotoxic effect. These results were beneficial in the promotion of natural herbicide production using biotechnology.     

裂褶菌多糖的研究进展

裂褶菌多糖(Schizophyllan)是裂褶菌(Schizophyllum commune)的主要活性成分之一.综述了裂褶菌多糖结构、提取纯化工艺和生理活性功能等方面的研究进展.     

密度泛函法研究金丝桃素的结构特性与光活性

采用密度泛函法（Density functional theory method,DFT）在6-31G＊基组水平上对金丝桃素（Hypericin,4,4′,5,5′,7,7′-六羟基-2,2′M甲基-中位-萘骈二蒽酮,化学式为C30H16O8）的分子结构、轨道能量、电荷布居、红外图谱等进行了研究,并对分子中的不同氢键类型以及光活性的本质特性进行了讨论;同时对部分计算结果与实验数据进行了对比分析.结果表明,金丝桃素易于与生物分子发生作用从而破坏病变分子;理论计算的数据与一些已知的实验数据具有较好的吻合性,说明计算结果有效.     

有机改良剂对温室土壤及番茄质量的影响

研究了优培-海藻生物有机肥(Y)、微生物菌肥(W)和腐植酸有机肥对日光温室土壤的理化性质、有效态微量元素含量、酶活性以及番茄品质等方面的影响,旨在探索快速、简易且廉价的土壤改良方法,为日光温室土壤改良及有机蔬菜生产提供理论依据。结果表明,不同土壤改良剂对土壤p H无显著影响,在番茄生育期内土壤p H值始终在7.0以上,没有出现酸化问题;拉秧后,除中量腐植酸有机肥(FM)外,其他各处理均能有效降低土壤EC值并达到极显著水平;各处理对提升有效态Mn、Zn和Fe含量的效果不显著,其中,仅高量腐植酸有机肥处理(FH)能同时提高开花结果盛期0~20 cm和20~40 cm土层的有效态Zn含量,与CK相比,分别增加10.8%和13.2%;不同土壤改良剂均可提高土壤脲酶和蔗糖酶活性;不同土壤改良剂对碱性磷酸酶的酶活性影响较小;微生物菌肥对酸性磷酸酶和过氧化氢酶的酶活性影响相对明显;不同土壤改良剂均能提高番茄可溶性固形物、可溶性糖、可滴定酸和维生素C的含量,其中,中量腐植酸有机肥处理提高了番茄的糖酸比。土壤改良剂可有效改善日光温室土壤特性及番茄品质。     

艾纳香内生真菌抗细菌和炭疽菌的活性研究

为获得丰富的艾纳香内生真菌资源,筛选出抗性生防菌株,用于活性次生代谢产物的发现,通过水琼脂法对海南产艾纳香进行内生真菌分离,通过ITS序列分析,对其进行鉴定和分析。采用滤纸片法评价内生真菌发酵产物对细菌的抑制活性,采用平板对峙培养法评价艾纳香内生真菌对植物炭疽菌的拮抗作用。本研究共分离鉴定出191株内生真菌,分属于27属,45种,其中优势菌属为Diaporthe、Paraphoma、Ectophoma、Penicillium、Talaromyces、Hypoxylon、Phomopsis、Colletotrichum和Fusarium。抗细菌活性结果显示,Clonostachys、Fusarium和Diapothe属活性较强。抗炭疽病菌试验显示,Talaromyces、Ectophoma和Penicillium属活性较强。本研究初步探讨了海南产艾纳香内生真菌种类的多样性,并首次对其进行了抗病原菌活性筛查,获得的活性菌株可作为微生物源菌剂开发的重要材料。     

秸秆纤维素分解细菌的筛选与鉴定

利用纤维素琼脂选择培养基和刚果红染色方法,从不同来源的土样中分离出2个菌株,测定了其纤维素酶活性、小麦秸秆降解能力,并对纤维素降解能力强的两个菌株进行了分子鉴定。结果表明,两株高效纤维素分解菌在纤维素刚果红培养基上均能形成透明水解圈,利用16S r RNA序列测序并分析Genbank中的同源性,结合形态和理化性质确定为Bacillus thuringiensis和Bacillus anthracis。在37℃,p H为7的条件下测定了纤维素酶活力,SC1-3和XR2-5-4分别为1.41和1.59。这两株37℃下经15 d后小麦秸秆失重率达19.92%和22.83%。     

地稔凝集素的提取及凝血活性的研究

为研究和利用地稔的促凝血活性物质,以地稔为试材,提取地稔凝集素,研究pH、温度和糖等理化因素对凝血活性的影响。结果表明:经硫酸铵沉淀及透析提取的地稔凝集素具有红细胞凝集活性;碱性条件下,抑制作用明显,而酸性条件有较强促进作用;温度对凝集素凝血活性影响很小;半乳糖有明显促进作用。     

秸杆栽培食用菌拮抗菌株的鉴定及混菌发酵条件的优化

从海洋泥样和食用菌发酵料中分离出了32个菌株,从中筛选出了既具有较高的纤维素酶活性又具有对青霉(Penicillium spp)、木霉(Trichoderma spp.)、根霉(Rhizopus)、曲霉(Aspergillus spp)、毛霉(Mucro)较强拮抗能力的W-4、W-10、N-14三个菌株。经鉴定W-4、W-10分别属于放线菌中黄色节杆菌(Arthrobacter flavescens)和石灰壤诺卡氏菌(Nocardia calcarea),N-14属于细菌中的乳酸乳杆菌(Lactobacillus lactis)。通过正交试验对上述3个菌株混合发酵条件进行优化,确定在温度35℃、时间36h、pH7.5、装液量60ml/250ml时为最适发酵条件。在此条件下3个菌株混合发酵液纤维素酶活力仍然很高。同时混合发酵液对青霉、曲霉、毛霉、木霉、根霉的拮抗能力分别为单菌株发酵液的1.79倍、1.36倍、1.29倍、1.04倍、1.07倍。     

Shelf-Life of Spanish Mackerel (Scomberomorus commerson) from Northern Australian Waters

Abstract

The shelf-life of Spanish mackerel caught by line fishing in Northern Australian waters was evaluated. Spiked fish were stored in ice either headed and gutted or left uncut and subjected to sensory, nucleotide, pH, histamine and microbial analysts and the rigor pattern recorded. There was little difference between the two product forms. Rigor in uncut fish lasted for 14 ± 9.8 hours and in headed and gutted fish for 19.6 ± 16.3 hours. Spanish mackerel retained good sensory quality for up to 14 days. The bacterial load reached 105 cfu/g by 18 days. K values were low for most of the storage time, < 40%. Histamine levels did not develop more than 10 mg/kg during storage. The pH of Spanish mackerel did not change much even though bacterial levels become high.