| 主权项 |
1. A method for determining and/or engineering photosynthetic mutant algal strains comprising:
(A) pre-screening wild-type or parent strains to select for photosynthetic efficiency by
(1) measuring a quantum requirement of said wild-type or parent strains at a sub-saturating light intensity;(2) for wild-type or parent strains having a quantum requirement of 15 or less, further measuring photosynthetic capacity to select for strains having a relatively high Pmax per cellular mass, which includes a Pmax per cellular mass for oxygen evolution of at least about 100 nmol/mg dry weight/minute, a Pmax per cellular mass for carbon fixation of at least about 80 nmol/mg dry weight/minute, a μmax for specific growth rate of at least about 0.1 hr−1, or a combination thereof;(3) optionally further measuring a saturating light intensity on strains satisfying the requirements of (A)(1) and A(2) to screen for strains whose Is is at least 125 μE/m2/s;(4) optionally further measuring a respiration and/or maintenance rate on strains satisfying the requirements of (A)(1) and A(2), and optionally also (A)(3), to screen for strains whose respiration/maintenance rate is less than 10% of μmax and/or Pmax, wherein the pre-screening results in a group of wild-type and/or parent strains for further study; and(5) producing a high light acclimated state in the wild-type or parent, which wild-type or parent passes (A)(1) and (A)(2) and optionally (A)(3) and optionally (A)(4) to determine whether the high light acclimated wild-type or parent:
(a) has at least a two thirds reduction in mass of chlorophyll a per cell mass;(b) has Pmax per cell mass within 20% of Pmax per cell mass of the relatively low light (sub-saturating) adapted state of the wild-type or parent;(c) has an Is of at least 250 μE/m2/s; and(d) has a quantum requirement in a short term test under sub-saturating light of at most 125% of the wild-type or parent strain in a short term test under sub-saturating light; (B) cause genetic mutations in the group of wild-type and/or parent strains from pre-screening (A) to form genetic mutant strains; (C) screening the genetic mutant strains for photosynthetic efficiency in mass cultures by
(1) measuring a pigment content in said genetic mutant strains;(2) for genetic mutant strains having a pigment content that is reduced by at least about 50%, as compared to a pigment content of its corresponding wild-type and/or parent strain, further measuring photosynthetic capacity to select for strains having a relatively high Pmax per cellular mass, that is at least 75% of a Pmax per cellular mass of its corresponding wild-type and/or parent strain;(3) for genetic mutant strains satisfying both (C)(1) and (C)(2), measuring saturating light intensity, Is, to select for strains whose Is is at least 250 μE/m2/s and/or whose Is is at least twice that of its corresponding wild-type and/or parent strain;(4) for genetic mutant strains satisfying (C)(1)-(C)(3), measuring a quantum requirement at a sub-saturating light intensity to select for strains having a quantum requirement of 15 or less and/or at most 125% of the quantum requirement of its corresponding wild-type and/or parent strain; and(5) optionally, for genetic mutant strains satisfying (C)(1)-(C)(4), further measuring a respiration and/or maintenance rate to screen for strains whose respiration/maintenance rate is less than 10% of μmax and/or Pmax per cellular mass; and (D) further screening the genetic mutants resulting from screening (C) by measuring biomass productivity to select strains having relatively high biomass productivity, measured as ash-free dry weight per volume of culture per unit time and/or as ash-free dry weight per area of illuminated surface of the culture per unit time, at least 25% higher than that of the corresponding wild-type and/or parent strains. |
