The potential of bioflocculant-producing bacteria as inoculum for biofloc based systems

Aim: Biological flocculants has been widely used around the world to replace the usage of synthetic flocculants for wastewater treatment.Anew green technology using biological flocculant known as biofloc system was developed which offers zero water exchanged, low feed conversion ratio (FCR) and high nutritional profile. This study was conducted to determine the most potential bioflocculant-producing bacteria isolated from biofloc sampleinPacific Whiteleg shrimp,P. vannameiculture pond. Methodology: Biofloc sample was collected using Imhoff cone and bacteria was isolated. The most abundant bacteria isolated throughout P. vannamei culture period was selected for screening of bioflocculant-producing bacteria usingYPG medium and flocculation activity using floc-jar test. Results: Screening of bioflocculant-producing bacteria showed that B. infantis, N. aquimarinus, B. cereus, H. venusta, Pseudoalteromonas sp., and B. safensis were characterized as highly mucoid and ropy colony morpologies. The highest flocculation activity with 93% was showed by B. infantis followed by N. aquimarinus (91%), B. cereus (87%), H. venusta (79%), Pseudoalteromonas (78%), while the lowest flocculation activity was showed byB. safensiswith 69%. Interpretation: As bacteria grew, extracellular polymeric substances (EPS) produced were involved in flocculation process. Each bacteria produced different EPS composition which differed their ability in flocculation process. Therefore, bacteria with high flocculation activity are potentially used as inoculum to increase flocculation processinbiofloc production

Temperature Upshift Mostly but not Always Enhances the Growth of Vibrio Species: A Systematic Review

The spread of Vibrio spp. and the prevalence of vibriosis around the world are often correlated with global warming, especially an increase in sea surface temperature. However, many ecological and virulence factors also trigger the spread of Vibrio species, while vibriosis occurs at both low and high temperatures. Recent studies that focused on a single factor (e.g. temperature) and one species (e.g. V. vulnificus) also showed that single factors such as temperature were insufficient to explain the pathogenicity and virulence of Vibrio spp. In this review, we have compiled and discussed the existing literature on the effect of temperature on different growth and pathogenicity of Vibrio spp. A systematic literature search was conducted using Web of Science (WoS) and SCOPUS databases up to 1st January 2022. After applying the selection criteria, a final list of 111 articles was included in this review. We have found that only certain Vibrio spp. are positively impacted by the increase in temperature. The results showed that 47% of the articles reported an increase in growth with the increase in temperature, while 38% showed that the relationship is complex. Reduced growth (6%) and no effect (9%) were also reported. These results showed that most but not all Vibrio spp. were positively impacted by an increase in temperature. The results indicated that V. alginolyticus, V. cholerae, V. parahaemolyticus, and V. vulnificus are the biggest threats to human and animal wellbeing

Utilisation of raw palm oil mill effluent (POME) as a renewable substrate for fermentative H2 production: optimisation using statistical approach

ermentative H2 production was studied using raw POME as the substrate with heat-shock pre-treated POME anaerobic sludge acted as the inoculum. The effect of crucial operating variables (initial pH of medium, incubation temperature, and inoculum size) on H2 production was studied using Box−Behnken Design. A second-order polynomial regression model was generated to evaluate H2 production trend under conditions tested. The model analysis revealed the high significance of linear effects of initial pH, incubation temperature, and inoculum size (P < 0.01) towards H2 production. Similar results indicated that the interaction effect between initial pH and inoculum size, and interaction effect between incubation temperature and inoculum size were highly significant (P < 0.01). The regression model suggested that the optimum conditions were set to a pH value, incubation temperature and inoculum size of 6.4, 58.0°C and 8.0% v/v, respectively. In order to validate the optimum conditions determined by the model, heat-shock pre-treated POME anaerobic sludge was incubated with raw POME under optimum conditions. Validation experiment showed that a cumulative H2 volume of 239.0 mL was produced. Microbial community analysis of inoculum showed that mixed consortia between Clostridium sp. and other obligate anaerobic non-spore forming bacteria, mostly belonging to the Firmicutes and Bacteroidetes phyla were identified as the major H2-producers and were hugely responsible towards fermentative H2 production

Impact of COVID-19 on aquaculture sector in Malaysia: Findings from the first national survey

Abstract Malaysian aquaculture sector consists of 391,000 t of cultivated organisms produced per year with an economic value for over USD 700 million as estimated in 2019. The COVID-19 pandemic caused a large global human pandemic and it is currently ongoing, affecting profoundly Malaysian aquaculture, which is vital for seafood provision and security assurance. Thus, to increase our understanding about how the pandemic affects aquaculture sectors is crucial to design possible management measures both at local and national level. To do it, we designed a survey, starting in May 2020, consisting of 25 online questions to collect information about the impact of COVID-19 on the aquaculture sectors in Malaysia. A total of 105 respondents (2625 answered questions) was captured within the Movement Control Order (MCO) period and later extended to the Conditional MCO (CMCO). Almost 90 % of respondents was unanimous in answering that, and COVID-19 had a heavy effect on aquaculture-related activities in Malaysia; 80 % of them indicated the market demand and logistic bottlenecks (72 %) as major constraints on their aquaculture activities. While the major option to solve aquaculture COVID-19 related issues was the use of online market or digital platforms (76 %), a large fraction of respondents requested for specific assistance to support aquaculture activities (e.g. financial support). Most respondents (93 %) was aware about the necessity of the Standard Operation Procedure (SOP) provided by the relevant agencies during the MCO / CMCO. Present data are crucial to develop policy measures both at national and international level to support seafood sectors under pandemic

A novel study on the effect of rapid biofloc as pellet feed on the survival rate and water quality of mud crab, Scylla olivacea culture

In order to promote the optimum survival rate of mud crab, Scylla sp., in crablet culture, green technology approaches must be developed to increase the yield of mud crab production. The application of biofloc in Scylla sp. culture was proven successful in promoting a good crablet performance and sustaining a good water quality condition. Therefore, due to its importance, this study aimed to determine the survival rates of Scylla olivacea crablets cultured in tanks, fed with pelleted rapid biofloc aggregates. Three feeding trials were conducted consisting of commercial pellet (CP), rapid biofloc pellets (BP) and a mix of rapid biofloc pellets with commercial pellets (BP+CP) and were cultured up to 13 weeks of culture periods. The mud crab crablets were fed twice a day, while water exchanges were only conducted once per week. The survival rates were calculated at the end of the culture period while water quality parameters were regularly monitored. Overall, our findings showed that the survival rate in the BP+CP treatment was the highest with 30%, while 23.3% and 10% in CP and BP treatment, respectively. The water parameter was in optimum range in CP, BP and BP+ CP treatment tanks where pH ranged from 8.19 to 8.26, temperature between 26.68°C to 26.69°C and salinity between 32.17ppt to 33.16 ppt. Ammonium, NH4 + was below an optimum range with, 0.18mg/L in BP treatment and 0.21 mg/L in BP+CP as compared to CP. Meanwhile, nitrite, NO2 - was identified below 1mg/L which ranged between 0.07 and 0.08 mg/L. Therefore, it can be concluded that combination of commercial and pelleted rapid biofloc aggregates have the potential capability to increase the survival rate of mud crab crablet culture while sustaining good water quality parameters and nutrient level

In Vitro Antibacterial Effect of Lactobacillus plantarum Postbiotics Against Fish Bacterial Pathogens

The intensification of aquaculture farms leads to stressful conditions for fish. This causes the outbreak of bacterial diseases and lowers production in aquaculture. Probiotics and chemical treatments are effective, but it possesses a risk to the environment and human health. Postbiotics emerged to become one of the treatments for bacterial diseases. In this study, Lactobacillus plantarum GS12 and GS13 strains were used to determine the antibacterial effect of postbiotics on different pathogenic bacteria. The postbiotics were extracted and both strains show positive inhibition in the screening test. The postbiotics from both strains of L. plantarum were then used for further testing on minimum inhibitory concentration. Postbiotic from GS12 showed no inhibition activity, whereas GS13 has the lowest inhibition concentration of 8.0 µg ml⁻¹ when tested on Aeromonas hydrohila and Vibrio harveyi, and 16.7 µg ml⁻¹ when tested on A. salmonicida and V. parahaemolyticus. Postbiotic produced by L. plantarum GS13 had better capacity in terms of antibacterial effect compared to L. plantarum GS12. L. plantarum GS13 postbiotics may be useful against bacterial disease in the future. This study shows a potential alternative control measure for bacterial disease often occurring in aquaculture

Integration of Copperas and <i>Moringa oleifera</i> Seeds as Hybrid Coagulant for Turbidity and Ammonia Removal from Aquaculture Wastewater

The rapid development of the aquaculture industry has contributed to the high amount of nutrients in wastewater that subsequently led to eutrophication and deterioration of water quality. Aquaculture wastewater consists of uneaten fish feed, fecal and other excretion or residue of chemicals used. Thus, this study aimed to evaluate the performance of hybrid coagulants of Moringa oleifera (MO) and copperas for aquaculture wastewater treatment. In this present study, different formulations of MO and copperas were explored in the coagulation treatment of aquaculture wastewater using a jar test experiment. The FTIR and SEM analysis are used to determine the morphology and surface of MO. This study focuses on the effect of coagulant aids formulation, coagulant dosage, the effect of initial pH and coagulation time on turbidity and ammonia removal in the coagulation of aquaculture wastewater. The finding shows that the highest removal of turbidity and ammonia was obtained with the use of 80% MO and 20% copperas at the condition of initial pH of 6 at 20 min of coagulation time, with the highest percentage removal of 66% and 91%, respectively. The coagulation isotherm of hybrid coagulant 80:20 is well described with the Freundlich isotherm model which describes the surface heterogeneity

Study on the implementation of different biofloc sedimentable solids in improving the water quality and survival rate of mud crab, Scylla paramamosain larvae culture

Microbial communities in biofloc technology (BFT) are responsible in minimalize water exchange and producing microbial proteins that are beneficial as a supplementals diet for mud crab, Scylla paramamosain larvae culture. Therefore, a study was conducted to determine the effect of bacterial communities in different sedimentable solids in order to improve the water quality and survival rate of S. paramamosain larvae culture. The results successfully identified that the number of pathogenic bacteria, Vibrio spp. decreased when the heterotrophic bacteria thrived in treatment tank with 4 ml/L sedimentable solids. The group of heterotrophic bacteria were able to adapt in developing their population while effectively uptake the ammonium and nitrite components. The ammonium and nitrite level in treatment tank depleting at an early stage of the experiment, and constantly low until the end of experiments (ammonium <0.20 mg/L, nitrite <0.10 mg/L). The survival rates of S. paramamosain larvae in both control and treatment tanks were identified <2.0%, however, sedimentable solids of 2 ml/L was identified suitable to be applied in crab larvae culture as it can help to reach megalopa stages within 17 days of culture period. Overall, it can be concluded that bacteria communities in biofloc are able to regulate nutrients load and maintaining water quality and also help in increased survival rate and development performance in the low sedimentable solids of biofloc culture treatment. Therefore, sedimentable solids of 2 ml/L is suggested to be potentially applied in S. paramamosain larvae cultures from this research finding