Physiological and photobiochemical changes and growth in the heterotrophic strain Chlorella vulgaris g120 were studied during trophic conversion from heterotrophic to phototrophic growth regime. After the exposure of the Chlorella g120 culture to light, it revealed a significant activity of the electron transport (450–700 μmol e⁻ m⁻² s⁻¹ as measured by chlorophyll fluorescence) and high PSII photochemical yield F_v/F_m between 0.7 and 0.8. Fast fluorescence induction kinetics showed that PSII electron acceptors in the plastoquinone pool remained partly oxidized, indicating no downregulation of PSII electron transport. The data further revealed that high photobiochemical activity is lost in futile (protective) processes of non-photochemical quenching and respiration which indicate that surplus energy is dissipated in these processes. Pigment analysis showed low chlorophyll content − 0.35–1.15% as compared with exclusively phototrophic strain Chlorella vulgaris R-117. Nevertheless, the carotenoid content in g120 was relatively high − 0.20–0.33% of dry weight which resulted in a considerably high ratio of carotenoid/chlorophyll − 0.31–0.44. This strain probably does not possess the fully competent photosynthetic apparatus and can only partially adapt to phototrophy. We show that the heterotrophically grown g120 strain can undergo metabolic shift from heterotrophic to phototrophic growth regime. It might be an interesting strain from biotechnological point of view as a source of carotenoids, especially lutein.

在从营养型向营养型生长的营养转化过程中，研究了异养小球藻g120的生理和光生化变化及生长。小球藻g120培养物暴露于光后，它显示出显着的电子传输活性（通过叶绿素荧光测量为450-700μmole ^-  m ^-2  s ^-1）和高的PSII光化学产率F _v / F _m在0.7到0.8之间。快速的荧光诱导动力学表明，质体醌库中的PSII电子受体仍被部分氧化，表明PSII电子传递没有下调。数据进一步表明，在非光化学淬灭和呼吸作用的无效（保护性）过程中丧失了较高的光生化活性，这表明这些过程中耗散了多余的能量。颜料分析显示，与纯光养型小球藻相比，叶绿素含量低-0.35–1.15％R-117。然而，g120中的类胡萝卜素含量相对较高-干重的0.20-0.33％，这导致类胡萝卜素/叶绿素的比率相当高-0.31-0.44。该菌株可能不具备完全的光合作用能力，只能部分适应光养。我们显示异养生长的g120菌株可以经历从异养到光养生长制度的代谢转变。从生物技术的角度来看，它可能是一种有趣的菌株，是类胡萝卜素（尤其是叶黄素）的来源。