Abstract: Disclosed is a process for producing L-leucine which comprises culturing in a medium a microorganism belonging to the genus Escherichia and having resistance to a leucine analogue and an ability to produce L-leucine, allowing L-leucine to accumulate in the culture, recovering L-leucine therefrom.

Abstract: Disclosed is a process for producing an L-amino acid which comprises culturing a microorganism belonging to the genus Escherichia, having resistance to 2-ketobutyric acid and ability to produce the L-amino acid in a medium until the L-amino acid is accumulated in the medium, and recovering the L-amino acid therefrom.

Abstract: Disclosed is a process for producicng L-threonine, which comprises culturing in a medium a microorganism belonging to the genus Escherichia and having a resistance to cysteine or cystine, or their analogue and an ability to produce L-threonine until L-threonine is accumulated in the culture broth, and recovering L-threonine therefrom.

Abstract: A process is disclosed for producing L-threonine, the process involves culturing in a medium a microorganism of the genus Escherichia capable of producing L-threonine which has resistance to at least one of rifampicin, lysine, methionine, aspartic acid and homoserine, or a decreased ability to degrade L-threonine, accumulating L-threonine in the culture liquor and recovering L-threonine therefrom.

Abstract: A process is disclosed for producing L-threonine, the process involves culturing in a medium a microorganism belonging to the genus Escherichia and having resistance to rifampicin, lysine, methionine, aspartic acid and homoserine, accumulating L-threonine in the culture and recovirng L-threonine therefrom.

Abstract: An electrical multilayer contact, specifically for relays, comprises the following layers disposed upon each other on a contact support member:a first layer of a copper-nickel alloy for mechanically and electrically connecting the further layers to the support member,a second layer consisting of silver or having a very high silver content for adhering the further layers to the first layer,a third layer of a silver-tin oxide composition,a fourth layer of silver or a silver alloy, anda fifth layer of gold or an alloy having a high gold content.This multilayer structure is preferably used for both, the fixed contact member and the movable contact member of a relay contact couple. In this case, the upper surface of the multilayer contact structure disposed on the fixed contact is plane, while that on the movable contact is curved in one direction to cooperate with the opposite plane surface in forming a line contact.

Abstract: A flat type electromagnetic relay wherein respective members forming normally closed contacts and normally opened contacts and actuating such contacts are stacked on one another to substantially enclose electromagnet assembly of which core and coil frame are integrally formed to be flat. A balance spring urges a card operatively coupled to an armature of the assembly into non-attracted position of the armature for normal positions of the contacts with a balanced constant force with reference to attracting force to the armature and resilient force of normally opened contact spring. The assembly includes means for positioning the respective members when assembled with a single assembling direction.