TITLE:
Effects of light intensities and photoperiods on growth and proteolytic activity in purple non-sulfur marine bacterium, Afifella marina strain ME (KC205142)
AUTHORS:
Sujjat Al-Azad, Tan Kar Soon, Julian Ransangan
KEYWORDS:
Afifella marina; Light Intensity; Photoperiod; Proteolytic Activity; Purple Non-Sulfur Bacteria; Light Intensity; Photoperiod; Proteolytic Activity; Purple Non-Sulfur Bacteria
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.4 No.10,
October
16,
2013
ABSTRACT: Afifella marina strain ME (KC205142), a purple non-sulfur bacterium
was isolated from mangrove habitats of Sabah.
The effects of light intensities and photoperiods on proteolytic activity in Afifella marina strain ME (KC205142)
were investigated. Secretion of proteolytic enzymes in Afifella marina was preliminarily assessed by skim milk agarose
media. Subsequently, light intensities, such as, dark, 1000, 1500, 2000,
2500, 3000, 3500, 4000, 4500 and 5000 lux were used to evaluate the effects on
proteolytic activity in Afifella marina strain ME under anaerobic condition. After that, the effect of photoperiods on
proteolytic activity was monitored under anaerobic light condition (3000 lux)
at 0 h (0L/24D),
6 h (6L/18D), 12 h (12L/12D), 18 h (18L/6D) and 24 h (24L/0D)
of photoperiod. The
highest proteolytic activity of 74.67 U was recorded at 3000 lux illumination
light intensity. The proteolytic activity in bacterium Afifella marina strain ME was positively associated with the dry
cell weight. The proteolytic activity of 72.67 U in bacterium Afifella marina strain ME at 18 h (18L/6D) photoperiod is not
significantly different (p > 0.05) from proteolytic activity of 74.67 U recorded at continuous light (24L/0D) condition. Light intensity of
3000 lux, culture period of 48 h and a photoperiod of 18 h (18L/ 6D) were the optimum parameters for
proteolytic activity in bacterium Afifella
marina strain ME.