Study of the Multidrug Resistance of Enterobacteria Isolated from Waters and Tilapia Fishes from Fish Farms in the Sud-Comoé Region, Côte d’Ivoire

Microbial resistance to antibiotics is a global problem that threatens the lives of millions of people and affects several sectors, including aquaculture. The aim of the present study is to contribute to the monitoring of multi-resistant enterobacterial strains circulating in fish ponds in the Sud-Comoé region of south-eastern Côte d’Ivoire, more specifically in the Aboisso and Tiapoum departments. To this end, 20 samples of Tilapia fish (Oreochromis niloticus) and 60 samples of farm water were collected from 5 fish farms in the Sud-Comoé region. Microbiological analyses were based on the isolation and identification of enterobacteria on Mac Conkey + Ceftazidime medium. These analyses resulted in the isolation of 73 strains of enterobacteria, including 58 from fish and 15 from fish pond water samples. Antibiotic sensitivity tests carried out on enterobacteria isolated from water and fish samples showed high levels of resistance (100%) to the beta-lactam family (Amoxicilin + clavulanic acid, Ceftazidime). Klebsiella pneumoniae and Enterobacter spp. showed resistance to Ciprofloxacins (100%) and (25%) respectively. The study also showed that strains of Enterobacteriaceae were resistant to all 3 families of antibiotics, notably Beta-lactams, Fluoro-quinolones and Aminosides. The presence of multi-resistant Enterobacteriaceae in fish and pond water samples represents a public health risk.

Phylogenetics and Molecular Divergence of Tilapia Fish (Oreochromis Species) Using Mitochondrial D-Loop and Cytochrome b Regions

Understanding the level of genetic diversity in any population is an important requisite towards strategizing measures for conservation and improvement of stocks. This study focused on the assessment of phylogenetics and molecular divergence of tilapia fish species obtained from two populations (Domita in South-South and Odeda in South-West, Nigeria) using the displacement loop (D-loop) and cytochrome b region of the mitochondrial deoxyribonucleic acid (mtDNA). A total of 28 samples (15 from South-South and 13 from South-West) were used for the genetic analysis. DNA was extracted from the tissue of all the samples using Quik-gDNATM miniPrep kit. The D-loop containing the hypervariable region was sequenced for all samples from the two populations, while cytochrome b (Cyt b) region of mtDNA was only sequenced for samples from South-South population. Chromatograms of the sequences were viewed and edited using Bioedit software. Multiple sequence alignment was carried out using molecular evolutionary genetic analysis (MEGA) software before subsequent genetic analyses. Phylogenetic analysis grouped the samples into two clusters based on population. Also, when the two mitochondrial regions were pooled together, they clustered into two major groups based on mitochondrial regions. Analysis of molecular variance (AMOVA) revealed 37.32% variation within population and 62.68% variation among population with a significant fixation index of 0.627 (p 0.05). The genetic distance inferred between D-loop regions of South-South and South-West populations was 0.243. Maternal lineage analysis revealed that the origin of tilapia fish from both populations could be traced to Oreochromis spirilus and Oreochromis leucostictus based on mitochondrial D-loop region. The findings of this study revealed molecular divergence among the tilapia populations and may serve as pivot information for the genetic improvement of this important species.

罗非鱼(Tilapia)鱼皮提取明胶的工艺优化

以罗非鱼(Tilapia)鱼皮为原料,分别用碱法、酸法、酶法进行前处理,对3种方法的提取效果进行比较,筛选出最佳水解方法为酶法。优化了酶法处理后的漂白、熬胶工艺,获得鱼皮提取明胶的最佳工艺。结果显示,前处理采用0.2%的混合酶,调p H值至3.5,于40℃水浴中酶水解鱼皮1 h,用6%高锰酸钾溶液进行氧化漂白3 h,再用1.5%草酸溶液进行还原漂白45 min。控制p H值为5?6,分3次熬胶,每次分别将水浴加热升温至60℃、65℃、70℃,各加热2 h,过滤后将3次胶液合并,在真空度不低于500 mm Hg,温度不超过60℃的情况下浓缩至20%左右。然后在60℃的鼓风干燥箱干燥至明胶含水量14%以下,经粉碎机粉碎,即可得成品明胶。该工艺产品得率19.93%(湿基)、粘度13.1 m Pa·s、凝胶强度1034.3 g/cm2。

The calcium-binding activity of fish scale protein hydrolysates

The calcium-binding activity of tilapia scale protein hydrolysates sequentially hydrolyzed by trypsin, flavor enzyme and pepsin were investigated. The hydrolysates were divided into four fractions using G-15 gel chromatography, and the F3 fraction has the higher calcium-binding activity of 196.3 mg/g. The UV-vis and the Fourier transform infrared spectroscopy (FTIR) demonstrate that the amino nitrogen atoms and the oxygen atoms belonging to the carboxylate groups are the primary binding sites for Ca2+. The X-ray diffraction and scanning electron microscopy (SEM) confirmed the reaction between the peptde and calcium. The results obtained indicated that this fish scale protein hydroly-sates have potential as functional foods for calcium-supplementation.

Water Quality and Growth Performance of Nile Tilapia Fries Fed on Insect-Based Feeds

Fish feed is one of the main constraints on the growth of aquaculture in Kenya. The lack of high-quality and competitively priced feeds means that the fish farmers are unable to expand their production. To ensure that aquaculture remains viable and sustainable, it is necessary to optimize production through the utilization of locally available feeding materials. Insect-based feeds are alternative least-cost feeding resource in fish production. Using alternative protein sources such as black soldier fly larvae (BSF) and daphnia meal in place of fishmeal (Omena and Dagaa) is an ingenious strategy for sustainable fish aquaculture. This study evaluated the effect of four treatments: BSF, daphnia, Omena from Lake Victoria and Dagaa from Lake Tanganyika on the fish pond environmental parameters and fish fries’ performance (body weight and length). The experiment was carried out in a greenhouse with 30 fingerlings in each experimental unit. The feeding trials took 23 days. Results indicated that the four treatments have a varied effect on the BW and L of fish fries. A high growth rate was observed in Daphia, followed by BSF, Omena and Dagaa in that order. On the other hand, the treatments have varied effects on pond parameters with BSF promoting too much growth of algae. BSF have higher amounts of ammonia, nitrates and phosphorus, which stimulate the high growth of algae.

A preliminary review on population parameters and genetic diversity in Oreochromis mossambicus:meta-regression and haplotype diversity

Assessment of population parameters and genetic diversity is critical for the economic and threatened species,including Oreochromis mossambicus.The morphometric and population parameters data for O.mossambicus were extracted based on the available literature from various countries.Phylogenetic and genetic diversity were analyzed based on cytochrome c oxidaseⅠ(COⅠ)sequences of the mitochondrial DNA(mtDNA)gene.The population parameters(asymptotic length(L_(∞)),growth constant(K),growth performance index(Ø),approximate maximum age(t_(max)),standard length(L),and weight(W))results revealed a variation among the populations studied.The result categorized the population into two groups:South African populations located close to Zimbabwe,Mozambique,Namibia,Australia,and China,as GroupⅠ,and the Indian population placed close to Thailand,the Philippines,Indonesia,America,and Mexico as GroupⅡ.The meta-regression results reveal that temperature strongly correlated with weight.In contrast,other population factors showed no significant differences.The haplotype analysis based on COI of mtDNA displayed 21 haplotypes,which revealed low nucleotide(π=0.025)diversity.Haplotype diversity(HD)was 0.65.The haplotype analysis showed that Tajima(D)was negative(-0.82)and Fu’s Fs was positive(2.2),and both tests were not significant(P>0.05),whereas the overall F-statistic(F_(st))value was 0.40(P<0.001).In conclusion,population parameters,and genetic analysis indices a high variation among the O.mossambicus from different locations.Additionally,the population parameters for O.mossambicus in America,Asia,and Australia were more influenced by ecological factors.At the same time,the population parameters in the African continent were influenced more by genetic factors.

Integration of Fish and Poultry Farming into Cropping Systems to Improve Production Yields

This study aims to evaluate and compare the fertilizing effects of fish-breeding water and river water combined or not with composted poultry manure on the growth and production of okra and lettuce crops. Thus, a sample of 2000 Nile tilapia Oreochromis niloticus fry and a sample of 100 Cobb 500 strain chicks were reared and monitored for six months and fifteen days. Poultry manure and fish-breeding water were then collected and used to fertilize and water okra and lettuce crops. Two systems were used for the crops (okra and lettuce) tested in an elementary plot design with replicates for each treatment (T1: fish-breeding water alone;T2: river water alone;T3: fish-breeding water combined with manure;T4: river water combined with manure). Morphometric parameters and phenological traits of okra and lettuce crops as well as the total harvest weight and production yield were evaluated and compared between treatments. The results reveal better growth and higher yields (0.67 kg/m2 vs. 0.45 kg/m2) of okra crops that received treatment T1 compared to T2. The best growth and yields of lettuce were obtained with treatments T3 (3.34 kg/m2) and T1 (1.89 kg/m2) compared to T4 (1.23 kg/m2) and T2 (1.20 kg/m2). These results show that fish-breeding water combined with poultry manure can boost okra and lettuce production and would be a real asset to stimulate local agricultural development. Thus, the adoption of such an agro-ecological approach integrating fish farming and animal husbandry could increase local production and provide food of good nutritional quality.

即食调味罗非鱼块制备工艺研究

[目的]以新鲜罗非鱼为原料制备即食罗非鱼块产品。[方法]通过单因素及正交试验以成品感官品质为评价指标对即食调味罗非鱼块的腌制去腥、调味处理、高温烘制等加工工艺进行研究。[结果]最佳工艺为:食盐4%、白酒3%、姜12%、蒜12%、葱12%腌制30分钟,食盐3%、花椒粉3%、辣椒粉6%调味30分钟,在65℃条件下烘制2h取出冷却后放冰箱冷藏24小时,65℃下复烘1h,最后刷油在160℃条件下烘烤10min。[结论]按此工艺生产的即食调味罗非鱼鱼块具有咸淡适中、肉质软硬恰当、味道鲜香麻辣的口感。

一株鹅-鱼养殖环境下罗非鱼无乳链球菌的分离鉴定及药物敏感性分析

【目的】为确定鹅-鱼立体养殖环境下引发罗非鱼疾病的病原菌,通过分析病原菌的生长特性、致病性与药物敏感性,为罗非鱼病的深入研究与精准防控提供科学依据。【方法】从患病罗非鱼组织中分离病原菌,采用形态观察、生理生化鉴定、16S rRNA序列分析等方法鉴定菌株;绘制菌株生长曲线,分析温度、盐度及pH值对病原菌生长的影响;通过腹腔注射和拌料口服投喂方式人工回归感染健康罗非鱼,分析病原菌的致病性;采用药敏纸片法测定病原菌对11类共26种抗菌药物的敏感性。【结果】从患病罗非鱼的脑组织中分离纯化得到一株优势菌株,编号为SAYJN,经形态学观察、生理生化鉴定、16S rRNA序列分析及回归感染试验,鉴定此菌株为无乳链球菌(Streptococcus agalactiae);SAYJN菌株的生长迟缓期为0~5 h,对数期为5~12 h;最适生长温度37℃、最适pH值7.0、最适盐度为5‰。腹腔注射和拌料口服投喂SAYJN菌株均可感染健康罗非鱼;水温为29(±1)℃时,腹腔注射SAYJN菌液对罗非鱼有较强的致病性,半致死浓度(LC_(50))为2.4×10^(8)CFU/mL;SAYJN菌株致病力与其浓度和水温密切相关。SAYJN菌株对甲氧苄啶、庆大霉素、新霉素等6种药物产生耐药性,对恩诺沙星、环丙沙星、阿米卡星等4种药物中度敏感,对多西环素、氟苯尼考、利福平等16种药物敏感。【结论】无乳链球菌SAYJN菌株是鹅-鱼立体养殖环境下罗非鱼疾病爆发的主要病原菌,该菌的致病力强弱与其浓度和水温密切相关。

惠州西湖外来鱼类入侵与鱼类群落状况研究

【目的】摸清惠州西湖鱼类群落组成和外来鱼类入侵现状。【方法】2023年2月,在惠州西湖主湖区开展鱼类资源调查,运用Jaccard相似性指数、相似性分析、非度量多维尺度排序法等方法分析外来鱼类物种组成、丰度差异、分布格局、群聚结构和群落相似性。【结果】共捕获鱼类21种,包括鲤、鲫和鲢等16种土著鱼类以及豹纹翼甲鲇、齐氏罗非鱼、尼罗罗非鱼、伽利略罗非鱼和露斯塔野鲮5种外来鱼类。外来鱼类质量和数量分别占总渔获物的45.36%和44.18%。豹纹翼甲鲇和齐氏罗非鱼在5种外来鱼类中质量和数量占比相对较高,表明外来种群资源量具有一定规模;相似性分析结果表明,西湖平均Jaccard相似性指数处于相似等级(数值为0.62),表明惠州西湖鱼类群落空间分布相似度高;聚类分析结果表明,在78.73%的相似性水平时,惠州西湖鱼类群落可分为4组,但它们之间的差异未达到生态学意义上的差异显著(P>0.05)。【结论】惠州西湖各站点鱼类群落较为相似,豹纹翼甲鲇和齐氏罗非鱼在各个站点均有出现,入侵较为严重,亟需采取相应的防控措施。

玉米油乳液对重组罗非鱼肉品质的影响

【目的】提高莫桑比克罗非鱼(Oreochromis mossambicus,以下简称罗非鱼)碎肉的利用率,改善重组罗非鱼肉的品质。【方法】本研究将玉米油乳液添加在重组罗非鱼肉中,通过设置不同的玉米油乳液添加比,测定重组罗非鱼肉的质构、水分活度、持水性、色度、微观结构、低场核磁共振、傅里叶红外光谱等指标,探究玉米油乳液对重组罗非鱼肉的微观、质构特性、外观颜色、水分分布等特性的影响。【结果】(1)玉米油乳液增加了重组罗非鱼肉的硬度、胶着性、咀嚼性和弹性,当添加比为20%时,硬度、胶着性、咀嚼性和弹性最高,但对内聚性无明显影响。(2)玉米油乳液增强了重组罗非鱼肉的白度值和亮度值,降低了红度值和黄度值,在添加比为40%时,白度值和亮度值均最大;同时增强了重组罗非鱼肉蛋白的持水性,降低了水分活度,在添加比为20%时,水分活度最低。(3)添加不同比例玉米油乳液的重组罗非鱼肉均存在同样的特征吸收峰,说明玉米油乳液不会引起重组罗非鱼肉蛋白特征吸收峰的改变,峰强存在较小的差异。扫描电镜结果表明,玉米油乳液使重组罗非鱼肉蛋白微观结构变得更加致密、均匀。【结论】玉米油乳液的添加可以改善重组罗非鱼肉内部的组织结构,并且适当的添加比可以促进鱼肉组织之间紧密的结合,从而改变鱼肉组织的水分分布,提高重组罗非鱼肉的品质。【意义】玉米油乳液有效地改善了重组罗非鱼肉的品质和感官,因而可作为重组罗非鱼肉制品的品质改良剂,改善其凝胶性能和风味,用于开发新型的重组罗非鱼肉产品,为罗非鱼加工碎肉的高值化利用提供新思路。

Contribution of Garcinia kola to the Productivity and Economic Profitability of the Community Agricultural Area of Kedougou: Financial and Comparative Analysis of Production Factors

Inland fishing predominates in the Kedougou region, which has no coastline. This type of fishing does not yet meet the local population’s demand for fish products. In response to this concern, a Community Agricultural Estate housing an integrated fish farm was set up in the commune of Bandafassi, in the village of Itato. Since its creation, this production unit has been faced with the problem of sourcing high-quality, low-cost, monosex male Oreochromis niloticus fry. In order to overcome this constraint, the present research focuses on the contribution of Garcinia kola to the productivity and economic profitability of the Itato farm. The aim of the research is to assess fish production in the experimental set-up and the production costs of tilapia in a controlled environment. The comparative study of the various production factors shows disparities only in the input factor, where scenarios 2 and 3 use additional products. These are 17-α-methytestosterone for scenario 2 and Garcinia kola for scenario 3. These products significantly interfere with fish production, with a fairly high mortality rate for scenario 2 (25% for two production cycles/ cohort2 (B5, B6, B7 and B8) treated with 17-α-methytestosterone). As for scenarios 1 and 3, mortalities are 5% with or without recourse to additional products (G. kola). In addition, average fish production for the three (03) scenarios is estimated at 28687.5 kg/2 cycles. It varies from one scenario to another, i.e. 30937.5 kg/2 cycles for scenarios 1 and 3 and 24187.5 kg/2 cycles for scenario 2. It is therefore higher in scenarios 1 and 3 than in scenario 2. This difference is due to the fairly large losses of individuals in scenario 2. Furthermore, the analysis of the profit and loss accounts for tilapia production varies from one scenario to another depending on the type of farm: 476 Franc CFA for scenario 1, 610 Franc CFA for scenario 2 and 472 Franc CFA for scenario 3 (F CFA = franc of the French Colonies of Africa). The Average operating income for all the fish farming units is 34,726,142 Franc CFA. The highest (41,638,075 Franc CFA) and lowest (29,281,075 Franc CFA) ERs were observed in scenarios 3 and 2 respectively. It was 33,259,275 Franc CFA for scenario 1. The difference between the NERs of the three scenarios is more or less significant in terms of results. The operating result (OR) is positive in all 3 scenarios in our study. However, the scenario 3 system generates a higher rate of return (the ratio between an income and the capital employed to obtain that income) (74%) than that generated by the scenario 1 system (69%). As for the scenario 2 system, it generates a lower financial return than the two previous systems (67%). Above all, this work made it possible to construct an approach that would make it possible to answer such a question by relying successively on various methods: a typology, according to the production factors involved in the operation of the Community Agricultural Estate fish farm.

罗非鱼的热风干燥特性及其主要成分含量变化研究

研究了罗非鱼鱼片在40、50和60℃等不同热风温度下的干燥速度变化和热风干燥对鱼片的主要成分含量的影响。结果表明,当鱼片厚度一定时,温度越高干燥速度越快,同样厚度的鱼片在较高温度下的干燥时间要比较低温度下的干燥时间至少缩短9h;当温度一定时,鱼片的干燥速度明显受其厚度的影响,鱼片越薄,干燥越快,而且鱼片厚度对干燥速度的影响超过了温度。对于厚度一定的鱼片,在温度恒定时,鱼片中的粗蛋白质含量随着干燥时间的延长而下降。

浮床栽培空心菜对罗非鱼养殖池塘水体中氮和磷的控制

总氮和总磷一直被认为是引起水体富营养化的重要因子,而氨氮和亚硝酸盐氮是养殖过程中引起鱼类疾病的关键环境因子。此试验利用PVC管构建浮床,研究了浮床栽培空心菜对罗非鱼养殖池塘水体中N和P的控制效果。数据表明,在试验后期,池塘水体中总氮水平降至淡水养殖池塘废水排放二级标准,而总磷水平达到地表水环境质量二类标准,氨氮的水平控制在1mg/L以下,而亚硝酸盐氮水平则控制在0.1mg/L以下。从各处理组对污染物的去除情况来看,空心菜种植时间与种植面积均与N、P的去除效果呈现较好的正相关关系,种植时间越长(>60天),种植面积与去除效果的正相关性越明显。结果表明,在集约化养殖池塘中采用浮床栽培空心菜能够对氮和磷实现有效的控制,并且空心菜浮床覆盖率为20%时比10%和15%处理组更具有经济效益。该试验为淡水池塘罗非鱼的健康养殖提供了一个新的思路。

鱼皮明胶蛋白膜的制备及其性质改良

利用罗非鱼鱼皮提取明胶制备蛋白膜,考察了浸提条件和戊二醛的添加对明胶蛋白膜性质的影响.结果表明,利用罗非鱼鱼皮可以制备成无色透明的明胶蛋白膜.在80℃水浴条件下,伴随着明胶浸提时间的延长,膜的抗拉伸强度(TS)出现先上升后下降的趋势,在浸提时间为1.0 h时达到最大值.而膜的断裂延伸率(EAB)和水蒸气透过率(WVP)则随着浸提时间的增加而下降.然而,浸提时间对膜的透光率没有显著影响.另一方面,当利用质量分数为1%～4%(相对明胶蛋白)的戊二醛对蛋白膜进行改性时,膜的TS、EAB、WVP和溶解性均明显下降,而蛋白膜的色泽变黄,紫外线阻隔能力增强.利用SDS-PAGE分析发现,戊二醛的添加会使明胶分子发生交联反应,且反应更易在高分子成分之间发生.

响应面法优化罗非鱼鱼皮胶原多肽螯合镁的工艺条件的研究

以罗非鱼鱼皮为原料,研究鱼皮胶原多肽和镁离子的螯合工艺条件。探讨了鱼皮胶原多肽与氯化镁的质量比、反应体系的pH、螯合温度、螯合时间等因素对鱼皮胶原蛋白螯合反应的影响;在单因素实验的基础上,通过响应面法对鱼皮胶原多肽与镁的螯合工艺条件进行优化,确定最佳的螯合工艺条件为:质量比1∶5、pH7.0、螯合温度70℃、螯合时间30min。在此条件下,螯合率达84.58%。通过对比螯合反应前后傅里叶变换红外光谱图的变化,证明了鱼皮胶原多肽与镁离子形成了新的螯合物。

罗非鱼与四种海水鱼鱼糜比较

比较了罗非鱼与工厂常用的四种海水鱼(黄姑鱼、带鱼、沙丁鱼、鲜丁鱼)鱼糜的基本成分含量、凝胶性能及鱼肌肉蛋白的营养价值。罗非鱼与海水鱼鱼糜的水分含量无显著差异(p>0.05),但蛋白质、脂肪、灰分、盐溶性蛋白含量及pH值有显著差异(p<0.05);罗非鱼鱼糜凝胶的强度、白度显著高于海水鱼(p<0.05),而凝胶的持水性显著低于海水鱼(p<0.05);通过分析几种鱼肌肉蛋白的必须氨基酸含量、氨基酸价(AAS)及氨基酸指数(EAAI),得出罗非鱼肌肉蛋白的营养价值高于黄姑鱼、带鱼和鲜丁鱼,但低于沙丁鱼。

稳定态二氧化氯对罗非鱼鱼丸品质变化的影响

为研究稳定态二氧化氯对罗非鱼鱼丸保鲜效果的影响,本文以感官评定(白度、硬度和弹性)、菌落总数、p H、挥发性盐基氮(TVB-N)及硫代巴比妥酸值(TBA)为鲜度指标定期取样测定,研究稳定态二氧化氯在冷藏条件下(4±1)℃对罗非鱼鱼丸的保鲜效果。结果表明:稳定态二氧化氯具有良好的杀菌和保鲜作用,能有效地抑制微生物的生长,并减缓蛋白质变性、脂肪氧化变质,延长罗非鱼鱼丸货架期6~10 d;其处理浓度为50 mg/L时保鲜效果显著。

酶法制取罗非鱼鱼鳞胶原蛋白寡肽的工艺

利用酶工程技术,以罗非鱼鱼鳞为研究对象,研究开发罗非鱼鱼鳞胶原蛋白寡肽制品。以蛋白酶种类、底物浓度、酶解时间、加酶量、温度、pH为实验因素,以胶原蛋白的提取率、平均分子量等为指标,确定酶解最佳条件为:在pH6,温度50℃,底物浓度150 g/L,加酶量1%MG+1%HHM的条件下,水解12 h,可得胶原提取率为55%,平均分子量为920 u左右。

罗非鱼鳞胶原多肽抗疲劳活性研究

以脱钙罗非鱼(Oreochromis niloticus)鳞为原料,利用复合酶(木瓜蛋白酶:中性蛋白酶=1∶1)进行酶解制备罗非鱼鳞胶原多肽,并对其粗蛋白含量、水分含量、氨基酸组成及分子量分布进行分析;通过对实验小鼠负重游泳时间、血清尿素氮、肝糖原含量测定,来探讨该胶原多肽的抗疲劳活性。结果表明:罗非鱼鳞胶原多肽能显著延长小鼠负重游泳时间(P<0.05),显著地降低小鼠的血清尿素氮含量(P<0.05)和提高小鼠体内肝糖原(P<0.05)的储备量。由此可见,罗非鱼鳞胶原多肽具有明显的抗疲劳活性。