Photo-biological hydrogen production by a temperature-tolerant mutant of Rhodobacter capsulatus isolated by transposon mutagenesis

Screening of high temperature tolerant strains is important for photo-fermentative hydrogen production in natural conditions which exhibit wide temperature variations. Hence, a temperature-tolerant strain of Rhodobacter capsulatus was isolated by transposon mutagenesis. The mutant strain Rhodobacter capsulatus MX01 could convert cornstalk hydrolysate into hydrogen successfully, and exhibited better hydrogen production performance at higher culture temperature (33 °C and 37 °C) and light intensity (5000 lx and 7000 lx) than the wild type strain. At 33 °C and 5000 lx, the total hydrogen production yield and rate of MX01 from cornstalk hydrolysate were 3.64 ± 0.18 mol-H₂/g-cornstalk and 40.07 ± 1.70 mmol-H₂/(h·g-cornstalk), respectively. The energy conversion efficiency of cornstalk hydrolysate to hydrogen for the mutant strain MX01 was 10.6%. This higher temperature- and light intensity-tolerant mutant MX01 could carry out photo-fermentation at outdoor settings, which is important for eco-friendly, low-cost and energy-saving practical application of bio-hydrogen production.