Growth and regulation of enzyme synthesis in the nitrilotriacetic acid (NTA)-degrading bacterium Chelatobacter heintzii ATCC 29600

Abstract

In the aerobic bacterium Chelatobacter heintzii, growth and regulation of enzymes involved in nitrilotriacetic acid (NTA) degradation have been investigated in chemostat culture during cultivation with glucose, NTA or mixtures thereof. In batch culture ,urn,, with NTA was 018 h-I and with glucose 0.22 h-I. Growth yields for both substrates were reduced at low dilution rates. During growth with NTA specific activity of the NTA monooxygenase (NTA-MO) exhibited a maximum at D = 003 h-I and gradually decreased with increasing dilution rates. In glucose-grown cells the specific activity as well as immunologically detectable NTA-MO protein was always close to the detection limit. During cultivation with different mixtures of NTA and glucose at a dilution rate of 006 h-I, both substrates were utilized simultaneously, irrespective of the NTA/glucose ratio and the presence of excess ammonia. Synthesis of both NTA-MO and iminodiacetic acid dehydrogenase became induced when NTA contributed to more than approximately 1-3% of the total carbon in the substrate mixture supplied. However, NTA was also degraded when the proportion of NTA in the mixture was lower than 1 %, which is consistent with the low constitutive level of expression for NTA-MO observed. Results are discussed with respect to NTA biodegradation during sewage treatment and in ecosystems.

Effect of media composition on yield values of bacteria growing on binary and ternary substrate mixtures in continuous culture

“…They found that those concentrations could be predicted from the biomass yields on the individual substrates and the proportions of the substrates in the feed. Similar results were obtained by Bally et al (1994) with a culture of Chelatobacter heintzii grown in a chemostat on mixtures of glucose and nitrilotriacetate and by Bitzi et al (1991) with a binary mixed culture grown on methanol, methylene chloride, acetone, and isopropanol. It should be noted, however, that only total yields in the mixtures and yields on individual substrates fed singly were measured in those studies; direct measurements of the yields on the individual substrates in the mixtures were not made.…”

“…The only previous work on this subject was done by Egli and coworkers (Bally et al, 1994;Bitzi et al, 1991;Egli et al, 1993;Kovářová et al, 1997) who concluded that yields were uninfluenced by the quantity of a given substrate in a multicomponent substrate. The difference in the observations is probably due to differences in experimental technique.…”

Bacterial growth yields on EDTA, NTA, and their biodegradation intermediates

“…Yields have been previously reported by Henneken et al (1998) for mixed culture EDTA biodegradation, Weilenmann et al (2004) for pure culture (DSM 9103) EDTA biodegradation, and Bally et al (1994) for pure culture NTA biodegradation. Yields for some of the common downstream intermediates (glyoxylate and glycine) have been previously reported by several sources for different bacterial species (Engelbrecht and McKinney 1957;Rutgers et al 1989).…”

Effect of metal complexation on the bioavailability of nitrilotriacetic acid to Chelatobacter heintzii ATCC 29600

“…It is readily biodegradable in a variety of environments including river water, sewage sludge and soils (Bally et al 1994;Firestone and Tiedje 1975;Tiedje 1975;Swisher et al 1973;Tiedje et al 1973). However, concern has been expressed that NTA may mobilise toxic metals in the environment through the formation of soluble metal chelates (Banat et al 1974;Samanidou and Fytianos 1990).…”