Oxygen supply for biostimulation of enzymatic activity in organic-rich marine ecosystems

The depletion of oxygen and the use of high energy cost electron acceptors for mineralisation processes are considered as one of the main reasons limiting degradation rates in aquatic organic-rich ecosystems. In this research the effect of two different biostimulation oxygen-releasing protocols were investigated using extracellular β-glucosidase activity rates. Organic-rich sediment and water was collected from the harbour of Genoa (Italy, North-Western Mediterranean) and oxygenation was generated either by positioning air tubes into the overlying water, or by placing oxygen release compounds (ORC) directly into the sediment, in laboratory microcosms. The increase in enzymatic activity was significant in the water compartment of the oxygenated microcosms (ANOVA, p<0.05) and greater for the ORC treatment. In particular, in the water, air tubes caused an increase in the β-glucosidase activity during the first 24 h (from 18.1 nmol l⁻¹ h⁻¹ (T=0, before the treatment) to 50.9 nmol l⁻¹ h⁻¹ (T=24 h)), while ORC induced a β-glucosidase activity increase over the whole period (from 12.4 nmol l⁻¹ h⁻¹ (T=0) to 63.7 nmol l⁻¹ h⁻¹ (T=60 d)) together with a reduction in carbohydrate (from 1.91 mg l⁻¹ (T=0) to 0.76 mg l⁻¹ (T=60 d)) and a sedimentary pH increase (from 8.04 (T=0) to 8.22 (T=60 d)). The response to ORC treatment in the overlying water was also evident in the potential carbohydrate turnover rate, decreasing from 0.86 h (T=0) to 0.06 h (T=60 d) and cell specific enzymatic activity, increasing from 3.8 (T=0) to 22.8 nmol l⁻¹ h⁻¹ cell⁻¹ (T=60 d). A less marked change was observed in the sediment.This research shows that the supply of oxygen directly into the sediment rather than water aeration is a better way of naturally enhancing enzymatic degradation rates in organic-rich marine ecosystems. The marked effect observed in the water following the sediment treatment suggests the occurring of a close association of decomposition processes within water and sediment compartments.     

激光生物刺激效应的理论研究与个例分析

文中深入的综述了近些年来激光生物刺激效应的研究进展,并尝试运用功率密度为16 mW/mm2的CO2激光对萌发的棉花种子进行辐照,进而研究激光对棉花种子萌发、幼苗生长发育以及抗逆性的影响。大量的研究表明,CO2激光辐照萌发的棉花种子,会对棉花种子的发芽率、出土后幼苗的生长发育状况、植株的抗逆性以及幼苗的生理生化代谢均有一定影响,但不同时间进行辐照造成的影响程度不同。     

Microbial intervention for better fish health in aquaculture: the Indian scenario

Aquaculture has evolved as the fastest growing food-producing sector and developed as an important component in food security. To keep a sustainable growth pattern, health management strategies must go beyond antibiotics and chemotherapeutics, which create resistant bacteria and immunosuppression in the host. Besides development of drug resistant bacteria and pathogens, the adverse effect of antibiotics is caused by their influence on the aquatic microflora, and the retention of harmful residues in aquatic animals. On the other hand, the microbes with their unique structure and cell wall components can trigger immunity, and thus exposure plays an important role in the evolution. Microbial intervention through an environmentally friendly approach is an alternative method of health management. India is endowed with a bounty of varied climatic conditions, microbial diversity and fish fauna and aquaculture systems offering challenges in biological and environmental pursuits. Producing about 4.4% of world’s fish and ranking third in global fish production, India trades about 2.4% in global fish market with the annual export earning being over $1311 million. Use of microbes for beneficial purposes is increasingly recognized as a valuable input for sustainable and responsible aquaculture. Microbial intervention in aquaculture can be broadly water/environment based through bioaugmentation, biostimulation, biocontrol measures, or (to generate) host response through probiotics, immunostimulants, and vaccines. Also, application of molecular methods such as polymerase chain reaction (PCR) and nucleic acid techniques are making increasing inroads into aquatic microbiological research in India. This paper elucidates all these aspects of microbial intervention in aquaculture, high-lighting Indian research and accomplishments.     

石油污染盐碱土壤生物修复模式

石油污染盐碱土壤的生物修复从机理上看,最主要的作用是微生物的降解能力,而植物和其他措施则主要起着辅助和刺激土壤微生物发挥效用的作用.因此,将石油污染盐碱土壤的生物修复模式划分为生物强化、生物刺激以及生物强化和生物刺激组合的三大类.生物强化主要强调石油污染物降解的直接加强措施,使该作用成为修复的主流或强势;而生物刺激则强调环境因素的改变,使生物强化效果提高的各种间接措施.在实际应用过程中,生物强化和生物刺激联合模式是提高石油污染物快速降解转化的主要生物修复模式.目前国内外的研究结果表明,在降解率方面,生物刺激＜生物强化＜生物强化和生物刺激的组合.根据污染土壤的具体情况,一般采用的生物刺激手段越丰富,降解效果越好.一般地,影响石油降解的顺序为营养＞表面活性剂＞电子受体.因此,生物强化是生物修复的主体,辅助以适当的生物刺激手段是石油污染盐碱土壤生物修复模式的首选.而成本有限时,应优先考虑营养刺激.     

Biostimulation and enrichment of 2,6-dichlorobenzamide-mineralising soil bacterial communities from dichlobenil-exposed soil

Eleven enrichment cultures of 2,6-dichlorobenzamide (BAM)-mineralising bacteria from a dichlobenil-exposed soil were enriched using three different media. Ten of the enriched mixed cultures had stimulated BAM mineralisation only in the presence of supplementary carbon and were able to utilise BAM as the sole nitrogen source, while only one was able to utilise BAM as the sole source of both carbon and nitrogen. Cultivation and DNA-based analysis of the mixed cultures suggested that different bacterial populations were stimulated by the three strategies. Our findings indicate that natural BAM-mineralising populations capable of using BAM as a source of nitrogen can be readily stimulated, enriched and maintained following sub-culturing from dichlobenil-treated soils by adding an alternative carbon source.     

农药污染土壤生物刺激修复技术研究进展

生物刺激作为一种环境友好且高效的生物修复技术,在污染土壤治理中具有独特优势,已成为国内外学者研究热点。针对当前农药污染土壤现状,本文综述了农药污染土壤及生物刺激修复技术的概念和范畴,重点从营养底物、表面活性剂、有机改良剂等角度阐述了生物刺激的方法和种类,探讨了影响生物刺激法修复农药污染土壤的主要因素,提出了生物刺激法目前存在的不足之处及未来发展趋势。本综述可为农药污染土壤生物刺激修复技术的发展和应用提供科学支撑。