Deciphering and engineering high-light tolerant cyanobacteria for efficient photosynthetic cell factories

Development and utilization of“liquid sunshine”could be one of key solutions to deal with the issues of fossil fuel depletion and increasing carbon dioxide.Cyanobacteria are the only prokaryotes capable of performing oxygenic photosynthesis,and their activity accounts for~25%of the total carbon fixation on earth.More importantly,besides their traditional roles as primary producers,cyanobacteria could be modified as“photosynthetic cell factories”to produce renewable fuels and chemicals directly from CO_(2) driven by solar energy,with the aid of cutting-edging synthetic biology technology.Towards their large-scale biotechnological application in the future,many challenges still need to be properly addressed,among which is cyanobacterial cell factories inevitably suffer from high light(HL)stress during large-scale outdoor cultivation,resulting in photodamage and even cell death,limiting their productivity.In this review,we critically summarized recent progress on deciphering molecular mechanisms to HL and developing HL-tolerant chassis in cyanobacteria,aiming at facilitating construction of HLresistant chassis and promote the future application of the large-scale outdoor cultivation of cyanobacterial cell factories.Finally,the future directions on cyanobacterial chassis engineering were discussed.

Experimental Investigation of a Fixed-geometry Two-dimensional Mixed-compression Supersonic Inlet with Sweep-forward High- light and Bleed Slot in an Inverted ＂X＂-type Layout

A fixed-geometry two-dimensional mixed-compression supersonic inlet with sweep-forward high-light and bleed slot in an inverted ＂X＂-form layout was tested in a wind tunnel. Results indicate： （1） with increases of the free stream Mach number, the total pressure recovery decreases, while the mass flow ratio increases to the maximum at the design point and then decreases; （2） when the angle of attack, a, is less than 6°, the total pressure recovery of both side inlets tends to decrease, but, on the lee side inlet, its values are higher than those on the windward side inlet, and the mass flow ratio on lee side inlet increases first and then falls, while on the windward side it keeps declining slowly with the sum of mass flow on both sides remaining almost constant; （3） with the attack angle, a, rising from 6° to 9°, both total pressure recovery and mass flow ratio on the lee side inlet fall quickly, but on the windward side inlet can be observed decreases in the total pressure recovery and increases in the mass flow ratio; （4） by comparing the velocity and back pressure characterristics of the inlet with a bleed slot to those of the inlet without, it stands to reason that the existence of a bleed slot has not only widened the steady working range of inlet, but also made an enormous improvement in its performance at high Mach numbers. Besides, this paper also presents an example to show how this type of inlet is designed.