Rakkhumkaew Numfon, Kawasaki Takeru, Fujie Makoto, Yamada Takashi
Center for Research and Development of Agricultural Industry, Faculty of Agro Industry Product and Innovation Technology, Srinakarinwirot University, Ongkarak 26120, Thailand.
Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima 739-8530, Japan.
J Biosci Bioeng. 2018 Mar;125(3):311-315. doi: 10.1016/j.jbiosc.2017.10.002. Epub 2017 Nov 1.
Chlorella viruses or chloroviruses contain a gene that encodes an enzyme that catalyzes chitin synthesis. This gene is expressed early in viral infections to produce chitin on the outside of the Chlorella cell wall. Interestingly, chitin synthesis by microalgal Chlorella cells in combination with chloroviruses represents a unique eco-friendly process for converting solar energy and CO into useful materials. However, during the final viral infection stage, the host cells are completely lysed, so chitin should be harvested before cells lyse. To increase chitin yields, slow-growing chlorovirus isolates were adopted and the viral replication process was modified with an inhibitor of DNA synthesis. The accumulation of chitin on the surface of Chlorella cells infected with one of nine chlorovirus isolates carrying the chitin synthase gene was compared with that of CVK2 (a standard virus)-infected cells. Chlorella cells infected with CVNF-1 (a slow-growing virus) accumulated chitin over the entire cell surface within 15 min post-infection (p.i.), and chitin continued to accumulate for up to 8 h p.i. before cells lysed. This was 2-fold longer than the chitin-accumulation period for cells infected with CVK2. The addition of aphidicolin delayed the progression of the virus replication cycle and extended the chitin-accumulation period of CVNF-1-infected cells to 12 h p.i. before cells lysed. Additionally, chitin production in the aphidicolin-treated CVNF-1-infected cells was approximately 6-fold higher than in CVK2-infected cells not treated with aphidicolin. Thus, chitin synthesis in a Chlorella-virus system may be prolonged by using slow-growing viral isolates treated with aphidicolin.
小球藻病毒或绿藻病毒含有一个编码催化几丁质合成的酶的基因。该基因在病毒感染早期表达，以在小球藻细胞壁外部产生几丁质。有趣的是，微藻小球藻细胞与绿藻病毒结合进行几丁质合成代表了一种将太阳能和一氧化碳转化为有用材料的独特环保过程。然而，在病毒感染的最后阶段，宿主细胞会完全裂解，因此几丁质应该在细胞裂解之前收获。为了提高几丁质产量，采用了生长缓慢的绿藻病毒分离株，并用DNA合成抑制剂对病毒复制过程进行了修饰。将携带几丁质合酶基因的9种绿藻病毒分离株之一感染的小球藻细胞表面几丁质的积累情况与感染CVK2（一种标准病毒）的细胞进行了比较。感染CVNF-1（一种生长缓慢的病毒）的小球藻细胞在感染后15分钟内（p.i.）在整个细胞表面积累几丁质，并且几丁质在细胞裂解前持续积累长达8小时p.i.。这比感染CVK2的细胞的几丁质积累期长2倍。添加阿非科林延迟了病毒复制周期的进程，并将感染CVNF-1的细胞的几丁质积累期延长至细胞裂解前12小时p.i.。此外，经阿非科林处理的感染CVNF-1的细胞中的几丁质产量比未用阿非科林处理的感染CVK2的细胞高约6倍。因此，通过使用经阿非科林处理的生长缓慢的病毒分离株，小球藻-病毒系统中的几丁质合成可能会延长。
