Astaxanthin accumulation in the green microalga Haematococcus pluvialis: Effect of initial phosphate concentration and stepwise/continuous light stress oleh Vinoj Chamilka Liyanaarachchi, Gannoru Kankanamalage Sanuji Hasara Nishshanka, Rankoth Gedara Malith Malsha Premaratne, Thilini Udayangani Ariyadasa, Pemaththu Hewa Viraj Nimarshana, Anushree Malik