CAJ | 학술논문

采用16S rDNA-PCR 菌群分离鉴定的方法，对循环水养殖条件下云纹石斑鱼(Epinehelus moara)幼鱼的胃、幽门盲囊、前肠、中肠和后肠的菌群结构进行了鉴定，用产酶菌筛选培养法对产消化酶的菌株进行了分离鉴定，并测试了各菌株消化酶的活力。研究发现，云纹石斑鱼幼鱼消化道内可培养的主要菌群为假单胞菌属(Pseudomonas)、微小杆菌属(Exiguobacterium)、不动杆菌属(Acinetobacter)、寡养单胞菌属(Stenotrophomonas)和葡萄球菌属(Staphylococcus)，其中产消化酶的菌株占可培养菌的55.6%。在产酶菌中，同一株菌产3种酶的有5株；产2种酶的有9株；中肠和后肠的菌株数最为丰富，胃次之，幽门盲囊和前肠菌群种类较少；产脂肪酶的菌株都集中在中肠。产消化酶的菌株主要以产蛋白酶和淀粉酶为主，且产酶量丰富，产蛋白酶活力最高达(87.732±1.134) U/mL；淀粉酶活力为(77.176±0.599)~(73.458±0.574) U/mL；产纤维素酶的菌仅一株，且酶活力较低。分析得知，消化道的菌群结构直接影响了外源性消化酶的种类与活性。本研究为工厂化循环水养殖条件下产酶有益菌的筛选提供了理论依据。
채용16S rDNA-PCR 균군분리감정적방법，대순배수양식조건하운문석반어(Epinehelus moara)유어적위、유문맹낭、전장、중장화후장적균군결구진행료감정，용산매균사선배양법대산소화매적균주진행료분리감정，병측시료각균주소화매적활력。연구발현，운문석반어유어소화도내가배양적주요균군위가단포균속(Pseudomonas)、미소간균속(Exiguobacterium)、불동간균속(Acinetobacter)、과양단포균속(Stenotrophomonas)화포도구균속(Staphylococcus)，기중산소화매적균주점가배양균적55.6%。재산매균중，동일주균산3충매적유5주；산2충매적유9주；중장화후장적균주수최위봉부，위차지，유문맹낭화전장균군충류교소；산지방매적균주도집중재중장。산소화매적균주주요이산단백매화정분매위주，차산매량봉부，산단백매활력최고체(87.732±1.134) U/mL；정분매활력위(77.176±0.599)~(73.458±0.574) U/mL；산섬유소매적균부일주，차매활력교저。분석득지，소화도적균군결구직접영향료외원성소화매적충류여활성。본연구위공엄화순배수양식조건하산매유익균적사선제공료이론의거。
The purpose of this research was to study the bacterial community structure in digestive tract and en-zyme production capacity of enzyme-producing bacteria, and provide reference for selection and application of probiotics for carnivorous fish culture. In this experiment, samples of juvenile saladfish (Epinehelus moara) stomach, pyloric caeca, foregut, midgut, and hindgut were obtained in recirculating aquaculture systems. Bacterial community structure was analyzed using 16S rDNA-PCR. The enzyme-producing bacteria were isolated and iden-tified by isolating and screening enzyme-producing bacteria. Moreover, the enzyme activities were tested. Twenty-seven strains were isolated and cultured under experimental conditions, including 13 strains of Pseudo-monas, 5 strains of Exiguobacterium, 7 strains of Acinetobacter, 1 strain of Stenotrophomonas, and 1 strain of Staphylococcus, which accounted for 48.2%, 18.5%, 25.9%, 3.7%, and 3.7%, respectively, of the isolated bacteria. The sequence homology of corresponding genes was greater than 98%. Fifteen strains produced enzymes and ac-counted for 55.6%of all bacteria;these bacteria included 7 strains of Pseudomonas, 5 strains of Exiguobacterium, 2 strains of Acinetobacter and 1 strain of Stenotrophomonas. Among these bacteria, 13 strains can produce both protease and amylase, whereas 4 strains can produce protease, amylase, and lipase. Among the enzyme-producing bacteria, 5 strains can produce 3 enzymes and 9 strains can produce 2 enzymes. Moreover, the bacteria in the midgut and hindgut were most abundant, and those in the stomach, diverticulum pyloricum and foregut were less abundant; the bacteria that produce lipase were concentrated in the midgut. Protease and amylase were the main enzymes produced by these bacteria; these two enzymes were highly productive, with protease activity up to (87.732±1.134) U/mL and amylase activity between (77.176±0.599) U/mL and (73.458±0.574) U/mL. Only one strain produced cellulase, and the activity was low. Under the experimental conditions, the isolated bacteria were all culturable. However, non-culturable bacteria cannot be isolated. Moreover, some culturable bacteria in the di-gestive tract could not be isolated because of limited testing conditions such as temperature, pH, culture medium, and other factors that may affect normal bacteria growth. In addition, isolation and identification took place under aerobic conditions, which is not similar to real gut conditions;thus, a large number of anaerobic bacteria were not isolated. Therefore, further investigation is needed to determine the actual bacterial community structure of the E. moara digestive tract. Our data showed that the bacterial community structure of the digestive tract directly af-fected the activity and diversity of exogenous digestive enzymes. This research provides a theoretical basis for selection of enzyme-producing bacteria in recirculating aquaculture conditions.