. 2020 Apr 28;13:1178636120913280. doi: 10.1177/1178636120913280

Table 3.

Optimization of culture conditions for production of extracellular keratinase from Bacillus cereus and Pseudomonas sp. in shake-flask cultivation.

Culture conditions	Bacillus cereus		Pseudomonas sp.		Culture conditions	Bacillus cereus		Pseudomonas sp.
Culture conditions	OD (280 nm)	Enzyme activity (U/mL)	OD (280 nm)	Enzyme activity (U/mL)	Culture conditions	OD (280 nm)	Enzyme activity (U/mL)	OD (280 nm)	Enzyme activity (U/mL)
Incubation temperature (°C)					pH
35	1.80	36.00 ± 1.00	1.50	30.00 ± 2.00	6.5	1.70	34.00 ± 2.64	1.67	23.33 ± 3.51
37	2.10	42.00 ± 2.64	2.05	41.00 ± 3.60^a	7.5	2.03	40.67 ± 1.15	1.53	30.67 ± 2.51
39	2.85	57.00 ± 2.00^a	1.80	36.00 ± 1.00	8.5	2.62	52.33 ± 1.15	1.70	34.00 ± 1.00
41	2.63	52.66 ± 2.08	1.48	29.66 ± 1.53	9.5	2.82	56.33 ± 1.52^a	2.17	43.33 ± 1.52^a
43	2.23	44.66 ± 1.53	1.10	22.00 ± 2.65	10.5	2.33	46.67 ± 4.16	1.83	36.67 ± 1.52
Inoculum volume (%, mL)					Incubation period (h)
1.00	1.82	36.33 ± 1.52	1.05	21.00 ± 1.00	24	0.80	16.00 ± 1.00	0.35	07.00 ± 2.00
2.00	2.18	43.67 ± 1.52	1.50	30.00 ± 2.00	48	1.35	27.00 ± 2.00	0.88	17.67 ± 2.51
3.00	2.78	55.67 ± 2.08^a	1.95	39.00 ± 1.00^a	72	1.88	37.67 ± 2.51	2.20	44.00 ± 1.00^a
4.00	2.55	51.00 ± 1.00	1.25	25.00 ± 2.00	96	3.01	60.00 ± 1.00^a	1.63	32.67 ± 1.52
5.00	1.98	39.67 ± 1.52	0.90	18.00 ± 1.00	120	2.07	41.33 ± 1.52	1.45	29.00 ± 1.00
Substrates					Agitation speed (r/min)
Human hair	1.12	22.33 ± 2.51	1.00	20.00 ± 1.00	100	2.42	48.33 ± 3.51	1.49	29.83 ± 3.40
Feather meal	2.73	54.67 ± 1.52^a	2.07	41.33 ± 1.52^a	150	2.87	57.33 ± 2.08^a	1.90	38.00 ± 3.00^a
Raw feather	2.15	43.00 ± 2.00	1.65	33.00 ± 2.00	200	1.20	39.33 ± 2.36	1.62	32.33 ± 2.51
					250	1.69	33.83 ± 3.01	1.15	23.00 ± 3.00
Carbon sources					Nitrogen sources
Glucose	1.58	31.67 ± 1.52	0.88	17.67 ± 3.05	Peptone	2.17	43.33 ± 1.52	1.02	20.33 ± 1.52
Fructose	1.80	36.00 ± 1.00	1.25	25.00 ± 2.00	Tryptone	2.45	49.00 ± 2.00	1.80	36.00 ± 1.00
Maltose	2.17	43.33 ± 1.52	1.82	36.33 ± 2.30^a	Yeast extract	2.80	56.00 ± 1.00^a	2.10	42.00 ± 2.00^a
Starch	2.80	56.00 ± 2.00^a	1.50	30.00 ± 2.00	Sodium molybdate	1.75	35.00 ± 2.00	1.30	26.00 ± 1.00
Lactose	1.35	27.00 ± 2.00	1.00	20.00 ± 1.00	Ammonium sulfate	1.35	27.00 ± 2.00	0.80	16.00 ± 1.00

All conditions were conducted on basal medium; results are expressed as mean ± SD for triplicate.

Best result.