因为DNA易于人工提取，传统的自然遗传转化研究很少关注DNA的来源及给体细胞的作用，但这样的实验室科研显然无法回答自然条件下发生的转发过程及其生物学意义。近20年来，在5项国家自然科学项目的连续资助下，我们发现在在固态基质表面发生的枯草芽孢杆菌细胞-细胞转化的效率明显高于等量游离DNA-细胞，也高于传统的二步法转化，且细胞间转化时的共转化片段至少可达1268 kb。此外，饥饿、抗生素等压力胁迫可通过影响给体细胞大幅度提高细胞间转化效率，且这种DNA给体细胞特性不仅普遍适用于不同枯草芽孢杆菌菌株，而且也适用于地衣芽孢杆菌。说明在环境中进行的这类基因水平转移过程中DNA给体细胞确实可能具有我们尚不太了解的重要生物学功能。通过细胞学和遗传学手段对DNA给体细胞在转化过程中的功能开展更深入、系统的研究，可望为进一步揭示自然转化的实质及其与生物进化、生物多样性等的关系提供新的研究思路，形成理论突破。

Since DNA is easily been prepared, traditional studies of natural genetic transformation have paid little attention to the source of DNA and the role of the DNA donor cells. However, such laboratory artifacts cannot explain how this process occurs in nature and elucidate its biological significance. In the past 20 years, under the continuous support of 5 projects of National Natural Science Foundation of China, we confirmed that the cell - cell transformation efficiency of Bacillus subtilis occurred on solid base was significantly higher than that of equivalent free DNA- cell, and was also higher than that of traditional two-step transformation process. Meanwhile, the longest co-transfer DNA fragment could reach at least 1268 kb in the cell to cell transformation process. In addition, stresses such as starvation and exposure to antibiotics further enhanced the cell-cell transformation efficiency by affecting the donor cells, and such kind of DNA donor characteristic was found not only be ubiquitous among Bacillus subtilis strains, but also be applicable to some Bacillus licheniformis strains. Therefore, the above results suggest that the DNA donor cells may really have some unknown biological significance when such horizontal gene transfer process take place in the natural environments. By means of cytology and genetics, a more in-depth and systematic study of the function of DNA donor cell in the transformation process is expected to provide new research ideas and theoretical breakthroughs for further revealing the nature of natural transformation and its relationship with biological evolution and biodiversity.