4.1.3 Bacterial Production and Destruction of 

 Organic Matter 



VASSILIY M, KUDRYATSEV, VLADIMIR O. MAMAEV*. and TAMARA F. STRIGUNKOVA* 



^Institute of Global Climate and Ecoloi;y. Stale Committee for Hydrometeorology and Academy of Sciences, Moscow. USSR 



'Bach Biochemistrs- Institute and the Academy of Sciences, Moscow, USSR 



Introduction 



Bacteria play an important role in mineralization and 

 detoxication of anthropogenic materials (e.g., oil hydrocarbons, 

 pesticides, anionic surfactants, and heavy metal compounds) 

 (Larsson & Lemkemeier, 1981; Tsyban, 1981; Bernard & 

 George, 1986;Braginsky, 1986; Sahasrabudhe& Modi, 1987; 

 Tsyban f/«/., 1987d; Kirsof/«/., 1988; O'Connor & Huggett, 

 1988). While considerable data have been published on the 

 processes and mechanisms of organic matter destruction, the 

 extent of biological self-purification have not been studied 

 thoroughly enough, especially in subarctic and arctic areas of 

 the World Ocean. In these regions, characterized by low 

 temperatures and increasing anthropogenic load, the role of 

 microbial transtomiationofcontaminants becomes considerably 

 more important. In this regard, the assessment of bacterial 

 production, destruction of organic matter, and the transfonnation 

 of toxic organic compounds of anthropogenic origin is very 

 important to determine the assimilation capacity, self- 

 purification of organic contaminants, and prognosis of marine 

 ecosystems. 



Materials and Methods 



The production-destruction process affected by bacteria 

 in the Bering and Chukchi Seas was studied in July-August 

 1988 during the third Soviet-American ecological expedition. 

 Bacterial production and the rate of organic matter (OM) 

 destruction was measured in the Gulf of Anadyr, Bering and 

 Chukchi Seas (Fig. 1 ). 



Dark CO, assimilation was measured by the Romanenko 

 and Kuznetsov ( 1 974) method. Details are given in Methodical 

 Foundationsof Integrated Ecological Monitoring of the Ocean 

 ( Tsyban ef«/., 1988) and Kuznetsov and Dubinina( 1989). To 

 determine dark CO, assimilation, water samples were taken 

 from standard hydroiogical depths with Niskin bottles and 

 added to 100-ml stoppered bottles. The bottles were tilled in 

 the same way as samples taken for soluble oxygen (i.e.. Hushed 

 with 3 water volumes). The bottles, filled with water, were 

 placed in dark sacks and 0.5 ml of NaV CO,(specific activity 

 about 20 X Kfcounts/min) were added. Bottles were stoppered 

 without air bubbles under the stopper. Duplicate samples were 

 taken from each depth. Two reference bottles were included at 

 each station and, apart from radioactive sodium carbonate, 1 ml 

 of 40% fomialdehyde solution was added. Bottles inside the 

 sack were tightly closed to light and incubated at surface 

 seawater temperature. 



BactenjI Decomposition 



produclion 1 of organic matter 



0.5g CIm- BJ per l.Og Clttt 



• Station number 



36 S^^ 

 ^35 



d1 .19 



Fig. 1 . Bacterial prttductitin and dcctMiipttsitnin olarganic matter in the 0.5 to 

 4,'^ m layer in the Gulf of Anadyr, and central Bering Sea. summer, 

 1988. 



After suitable exposure, depending on temperatures, 

 formalin ( I ml ) was added to each bottle. Water samples were 

 filtered through a "Sinpor" membrane filter having pore diameter 

 0.35 or 0.45 |Jm and immediately treated with 1 '7c hydrochloric 

 acid to remove residues of radioactive carbonate. Radioactivity 

 was measured by means of liquid scintillation. Dark COj 

 assimilation was calculated by the following formula: 



c = Cffe ■ 



Rxt 



where 



r = 



^catl, ~ 



R = 



dark CO, assimilation, |ig C/l/d; 



radioactivity on filters, dpm/min; 



carbonate contents in the water, mg C/1 

 (determined by direct titration with 0.1 

 HCl in the presence of methyl red tracer); 



isotope added to each bottle, dpm/min; 



incubation time. 24 hours 



75 



