Table 1.

Effect of nitrogen source, initial pH, temperature, and aerobic and anaerobic conditions on the production of nisin Z by Lactococcus lactis strains ID1.5, ID3.1, ID8.5, PR3.1, and PD4.7 strains.

Conditions tested	Antimicrobial activity (AU·mL−1)∗
	ID1.5	ID3.1	ID8.5	PR3.1	PD4.7
Tryptone	125000	114000	91000	74000	57000
Animal peptone	57000	62000	51000	49000	40000
Soy peptone	23000	34000	14000	30000	34000
Casein peptone	91000	137000	57000	125000	114000
Meat extract	8600	9200	4300	5700	4300
Yeast extract	12800	12800	9300	11000	4300
Initial pH
4.5	6400	12800	10000	12000	4200
5.0	31000	26000	20000	23000	13000
5.5	34000	32000	46000	40000	52000
6.0	80000	114000	114000	137000	137000
6.5	91000	91000	114000	114000	80000
7.0	13000	20000	23000	16000	17000
Temperature (°C)
20	7000	6000	5000	7000	4000
25	14000	17000	17000	13000	10000
30	14000	17000	19000	14000	10000
35	6400	10000	7000	9000	3000
40	400	300	300	400	300
Aerobiose	46000	31000	51000	46000	40000
Anaerobiose	31000	17000	14000	13000	11000

^∗All experiments were performed in triplicate, and the averages of two independent tests were calculated.